Change search
Refine search result
12 1 - 50 of 83
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Adamczyk, Andrew J.
    et al.
    Cao, Jie
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Warshel, Arieh
    Catalysis by dihydrofolate reductase and other enzymes arises from electrostatic preorganization, not conformational motions2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 34, p. 14115-14120Article in journal (Refereed)
    Abstract [en]

    The proposal that enzymatic catalysis is due to conformational fluctuations has been previously promoted by means of indirect considerations. However, recent works have focused on cases where the relevant motions have components toward distinct conformational regions, whose population could be manipulated by mutations. In particular, a recent work has claimed to provide direct experimental evidence for a dynamical contribution to catalysis in dihydrofolate reductase, where blocking a relevant conformational coordinate was related to the suppression of the motion toward the occluded conformation. The present work utilizes computer simulations to elucidate the true molecular basis for the experimentally observed effect. We start by reproducing the trend in the measured change in catalysis upon mutations (which was assumed to arise as a result of a "dynamical knockout" caused by the mutations). This analysis is performed by calculating the change in the corresponding activation barriers without the need to invoke dynamical effects. We then generate the catalytic landscape of the enzyme and demonstrate that motions in the conformational space do not help drive catalysis. We also discuss the role of flexibility and conformational dynamics in catalysis, once again demonstrating that their role is negligible and that the largest contribution to catalysis arises from electrostatic preorganization. Finally, we point out that the changes in the reaction potential surface modify the reorganization free energy (which includes entropic effects), and such changes in the surface also alter the corresponding motion. However, this motion is never the reason for catalysis, but rather simply a reflection of the shape of the reaction potential surface.

  • 2.
    Al-Smadi, Derar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Enugala, Thilak Reddy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kessler, Vadim
    Mhasal, Anil Rhanu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kamerlin, Shina Caroline Lynn
    Kihlberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Norberg, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Chemical and Biochemical Approaches for the Synthesis of Substituted Dihydroxybutanones and Di-, and Tri-Hydroxypentanones2019In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 84, p. 6982-6991Article in journal (Refereed)
    Abstract [en]

    Polyhydroxylated compounds are building blocks for the synthesis of carbohydrates and other natural products. Their synthesis is mainly achieved by different synthetic versions of aldol-coupling reactions, catalyzed either by organocatalysts, enzymes or metal-organic catalysts. We have investigated the formation of 1,4-substituted 2,3-dihydroxybutan-1-one derivatives from para- and meta-substituted phenylacetaldehydes by three distinctly different strategies. The first involved a direct aldol reaction with hydroxyacetone, dihydroxyacetone or 2-hydroxyacetophenone, catalyzed by the cinchona derivative cinchonine. The second was reductive cross-coupling with methyl or phenyl glyoxal promoted by SmI2 resulting in either 5-substituted 3,4-dihydroxypentan-2-ones or 1,4 bis-phenyl substituted butanones, respectively. Finally, in the third case, aldolase catalysis was employed for synthesis of the corresponding 1,3,4-trihydroxylated pentan-2-one derivatives. The organocatalytic route with cinchonine generated distereomerically enriched syn products (de = 60−99 %), with moderate enantiomeric excesses (ee = 43−56%), but did not produce aldols with either hydroxyacetone or dihydroxyacetone as donor ketones. The SmI2-promoted reductive cross-coupling generated product mixtures with diastereomeric and enantiomeric ratios close to unity. This route allowed for the production of both 1-methyl- and 1-phenylsubstituted 2,3-dihydroxybutanones, at yields between 40−60%. Finally, the biocatalytic approach resulted in enantiopure syn (3R,4S) 1,3,4-trihydroxypentan-2-ones.

  • 3.
    Amrein, Beat A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Duarte, Fernanda
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Janfalk Carlsson, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Naworyta, Agata
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Mowbray, Sherry L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kamerlin, Shina C. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Expanding the catalytic triad in epoxide hydrolases and related enzymes2015In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 10, p. 5702-5713Article in journal (Refereed)
    Abstract [en]

    Potato epoxide hydrolase 1 exhibits rich enantio- and regioselectivity in the hydrolysis of a broadrange of substrates. The enzyme can be engineered to increase the yield of optically pureproducts, as a result of changes in both enantio- and regioselectivity. It is thus highly attractive inbiocatalysis, particularly for the generation of enantiopure fine chemicals and pharmaceuticals.The present work aims to establish the principles underlying the activity and selectivity of theenzyme through a combined computational, structural, and kinetic study, using the substratetrans-stilbene oxide as a model system. Extensive empirical valence bond simulations have beenperformed on the wild-type enzyme together with several experimentally characterized mutants.We are able to computationally reproduce the differences in activities between differentstereoisomers of the substrate, and the effects of mutations in several active-site residues. Inaddition, our results indicate the involvement of a previously neglected residue, H104, which iselectrostatically linked to the general base, H300. We find that this residue, which is highlyconserved in epoxide hydrolases and related hydrolytic enzymes, needs to be in its protonatedform in order to provide charge balance in an otherwise negatively-charged active site. Our datashow that unless the active-site charge balance is correctly treated in simulations, it is notpossible to generate a physically meaningful model for the enzyme that can accurately reproduceactivity and selectivity trends. We also expand our understanding of other catalytic residues,demonstrating in particular the role of a non-canonical residue, E35, as a “backup-base” in theabsence of H300. Our results provide a detailed view of the main factors driving catalysis andregioselectivity in this enzyme, and identify targets for subsequent enzyme design efforts.

  • 4.
    Amrein, Beat Anton
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab.
    Runthala, Ashish
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    In Silico-Directed Evolution Using CADEE2018In: Computational Methods in Protein Evolution / [ed] T. Tobias Sikosek, Springer Science+Business Media, LLC, part of Springer Nature , 2018, p. 381-415Chapter in book (Other academic)
  • 5.
    Amrein, Beat Anton
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Steffen-Munsberg, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Szeler, Ireneusz
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Purg, Miha
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kulkarni, Yashraj
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    CADEE: Computer-Aided Directed Evolution of Enzymes2017In: IUCrJ, ISSN 0972-6918, E-ISSN 2052-2525, Vol. 4, no 1, p. 50-64Article in journal (Refereed)
    Abstract [en]

    The tremendous interest in enzymes as biocatalysts has led to extensive work in enzyme engineering, as well as associated methodology development. Here, a new framework for computer-aided directed evolution of enzymes (CADEE) is presented which allows a drastic reduction in the time necessary to prepare and analyze in silico semi-automated directed evolution of enzymes. A pedagogical example of the application of CADEE to a real biological system is also presented in order to illustrate the CADEE workflow.

  • 6.
    Aqvist, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Kamerlin, Shina C. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Conserved Motifs in Different Classes of GTPases Dictate their Specific Modes of Catalysis2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 3, p. 1737-1743Article in journal (Refereed)
    Abstract [en]

    The GTPase superfamily of enzymes that hydrolyze GTP have a number of conserved sequence regions (the so-called "G-motifs"), and several of the subfamilies also require catalytic activation by specific GTPase-activating proteins. In the translational GTPases involved in protein synthesis, this activating function is instead accomplished by their interaction with the ribosome. Despite these similarities, there are distinct differences regarding some of the amino acid residues making up the GTPase active sites. This raises the question of whether or not the catalytic mechanisms of different types of GTPases are identical. We report herein extensive computer simulations of both the intrinsic GTP hydrolysis reaction of Ras and the considerably faster reaction activated by the interaction with RasGAP. The results of these calculations are compared to earlier simulations of GTP hydrolysis by EF-Tu on the ribosome and show that the favored reaction pathways are strongly dependent on the composition of the active site. By computing Arrhenius plots for the temperature dependence of the calculated free energy profiles, we further show that different mechanistic pathways are associated with distinct differences in activation entropies and enthalpies. The activation parameters are in good agreement with experimental data, and we conclude that calculations of Arrhenius plots from computer simulations can be very useful for dissecting the energetics of enzyme catalysis.

  • 7.
    Aqvist, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Exceptionally large entropy contributions enable the high rates of GTP hydrolysis on the ribosome2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 15817Article in journal (Refereed)
    Abstract [en]

    Protein synthesis on the ribosome involves hydrolysis of GTP in several key steps of the mRNA translation cycle. These steps are catalyzed by the translational GTPases of which elongation factor Tu (EF-Tu) is the fastest GTPase known. Here, we use extensive computer simulations to explore the origin of its remarkably high catalytic rate on the ribosome and show that it is made possible by a very large positive activation entropy. This entropy term (T Delta S-double dagger) amounts to more than 7 kcal/mol at 25 degrees C. It is further found to be characteristic of the reaction mechanism utilized by the translational, but not other, GTPases and it enables these enzymes to attain hydrolysis rates exceeding 500 s(-1). This entropy driven mechanism likely reflects the very high selection pressure on the speed of protein synthesis, which drives the rate of each individual GTPase towards maximal turnover rate of the whole translation cycle.

  • 8.
    Baier, Florian
    et al.
    Univ British Columbia, Michael Smith Lab, Vancouver, BC, Canada.
    Hong, Nansook
    Australian Natl Univ, Res Sch Chem, Canberra, ACT, Australia.
    Yang, Gloria
    Univ British Columbia, Michael Smith Lab, Vancouver, BC, Canada.
    Pabis, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Miton, Charlotte M.
    Univ British Columbia, Michael Smith Lab, Vancouver, BC, Canada.
    Barrozo, Alexandre
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Carr, Paul D.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT, Australia.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Jackson, Colin J.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT, Australia.
    Tokuriki, Nobuhiko
    Univ British Columbia, Michael Smith Lab, Vancouver, BC, Canada.
    Cryptic genetic variation shapes the adaptive evolutionary potential of enzymes2019In: eLIFE, E-ISSN 2050-084X, Vol. 8, article id e40789Article in journal (Refereed)
    Abstract [en]

    Genetic variation among orthologous proteins can cause cryptic phenotypic properties that only manifest in changing environments. Such variation may impact the evolvability of proteins, but the underlying molecular basis remains unclear. Here, we performed comparative directed evolution of four orthologous metallo-beta-lactamases toward a new function and found that different starting genotypes evolved to distinct evolutionary outcomes. Despite a low initial fitness, one ortholog reached a significantly higher fitness plateau than its counterparts, via increasing catalytic activity. By contrast, the ortholog with the highest initial activity evolved to a less-optimal and phenotypically distinct outcome through changes in expression, oligomerization and activity. We show how cryptic molecular properties and conformational variation of active site residues in the initial genotypes cause epistasis, that could lead to distinct evolutionary outcomes. Our work highlights the importance of understanding the molecular details that connect genetic variation to protein function to improve the prediction of protein evolution.

  • 9.
    Barrozo, Alexandre
    et al.
    Univ Southern Calif, Dept Chem, Los Angeles, CA 90089 USA..
    Blaha-Nelson, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Williams, Nicholas H.
    Univ Sheffield, Dept Chem, Sheffield S3 7HF, S Yorkshire, England..
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    The effect of magnesium ions on triphosphate hydrolysis2017In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 89, no 6, p. 715-727Article in journal (Refereed)
    Abstract [en]

    The role of metal ions in catalyzing phosphate ester hydrolysis has been the subject of much debate, both in terms of whether they change the transition state structure or mechanistic pathway. Understanding the impact of metal ions on these biologically critical reactions is central to improving our understanding of the role of metal ions in the numerous enzymes that facilitate them. In the present study, we have performed density functional theory studies of the mechanisms of methyl triphosphate and acetyl phosphate hydrolysis in aqueous solution to explore the competition between solvent-and substrate-assisted pathways, and examined the impact of Mg2+ on the energetics and transition state geometries. In both cases, we observe a clear preference for a more dissociative solvent-assisted transition state, which is not significantly changed by coordination of Mg2+. The effect of Mg2+ on the transition state geometries for the two pathways is minimal. While our calculations cannot rule out a substrate-assisted pathway as a possible solution for biological phosphate hydrolysis, they demonstrate that a significantly higher energy barrier needs to be overcome in the enzymatic reaction for this to be an energetically viable reaction pathway.

  • 10.
    Barrozo, Alexandre
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Borstnar, Rok
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Marloie, Gaël
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Kamerlin, Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Computational Protein Engineering: Bridging the Gap between Rational Design and Laboratory Evolution2012In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 13, no 10, p. 12428-12460Article, review/survey (Refereed)
    Abstract [en]

    Enzymes are tremendously proficient catalysts, which can be used as extracellular catalysts for a whole host of processes, from chemical synthesis to the generation of novel biofuels. For them to be more amenable to the needs of biotechnology, however, it is often necessary to be able to manipulate their physico-chemical properties in an efficient and streamlined manner, and, ideally, to be able to train them to catalyze completely new reactions. Recent years have seen an explosion of interest in different approaches to achieve this, both in the laboratory, and in silico. There remains, however, a gap between current approaches to computational enzyme design, which have primarily focused on the early stages of the design process, and laboratory evolution, which is an extremely powerful tool for enzyme redesign, but will always be limited by the vastness of sequence space combined with the low frequency for desirable mutations. This review discusses different approaches towards computational enzyme design and demonstrates how combining newly developed screening approaches that can rapidly predict potential mutation “hotspots” with approaches that can quantitatively and reliably dissect the catalytic step can bridge the gap that currently exists between computational enzyme design and laboratory evolution studies.

  • 11.
    Barrozo, Alexandre
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Duarte, Fernanda
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Carvalho, Alexandra T. P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Cooperative Electrostatic Interactions Drive Functional Evolution in the Alkaline Phosphatase Superfamily2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 28, p. 9061-9076Article in journal (Refereed)
    Abstract [en]

    It is becoming widely accepted that catalytic promiscuity, i.e., the ability of a single enzyme to catalyze the turnover of multiple, chemically distinct substrates, plays a key role in the evolution of new enzyme functions. In this context, the members of the alkaline phosphatase superfamily have been extensively studied as model systems in order to understand the phenomenon of enzyme multifunctionality. In the present work, we model the selectivity of two multiply promiscuous members of this superfamily, namely the phosphonate monoester hydrolases from Burkholderia caryophylli and Rhizobium leguminosarum. We have performed extensive simulations of the enzymatic reaction of both wild-type enzymes and several experimentally characterized mutants. Our computational models are in agreement with key experimental observables, such as the observed activities of the wild-type enzymes, qualitative interpretations of experimental pH-rate profiles, and activity trends among several active site mutants. In all cases the substrates of interest bind to the enzyme in similar conformations, with largely unperturbed transition states from their corresponding analogues in aqueous solution. Examination of transition-state geometries and the contribution of individual residues to the calculated activation barriers suggest that the broad promiscuity of these enzymes arises from cooperative electrostatic interactions in the active site, allowing each enzyme to adapt to the electrostatic needs of different substrates. By comparing the structural and electrostatic features of several alkaline phosphatases, we suggest that this phenomenon is a generalized feature driving selectivity and promiscuity within this superfamily and can be in turn used for artificial enzyme design.

  • 12.
    Barrozo, Alexandre
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Liao, Qinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Esguerra, Mauricio
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Marloie, Gael
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Florian, Jan
    Loyola Univ Chicago, Dept Chem & Biochem, Chicago, IL 60660 USA..
    Williams, Nicholas H.
    Univ Sheffield, Dept Chem, Sheffield S3 7HF, S Yorkshire, England..
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Computer simulations of the catalytic mechanism of wild-type and mutant beta-phosphoglucomutase2018In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 16, no 12, p. 2060-2073Article in journal (Refereed)
    Abstract [en]

    beta-Phosphoglucomutase (beta-PGM) has served as an important model system for understanding biological phosphoryl transfer. This enzyme catalyzes the isomerization of beta-glucose-1-phosphate to -glucose-6-phosphate in a two-step process proceeding via a bisphosphate intermediate. The conventionally accepted mechanism is that both steps are concerted processes involving acid-base catalysis from a nearby aspartate (D10) side chain. This argument is supported by the observation that mutation of D10 leaves the enzyme with no detectable activity. However, computational studies have suggested that a substrate-assisted mechanism is viable for many phosphotransferases. Therefore, we carried out empirical valence bond (EVB) simulations to address the plausibility of this mechanistic alternative, including its role in the abolished catalytic activity of the D10S, D10C and D10N point mutants of beta-PGM. In addition, we considered both of these mechanisms when performing EVB calculations of the catalysis of the wild type (WT), H20A, H20Q, T16P, K76A, D170A and E169A/D170A protein variants. Our calculated activation free energies confirm that D10 is likely to serve as the general base/acid for the reaction catalyzed by the WT enzyme and all its variants, in which D10 is not chemically altered. Our calculations also suggest that D10 plays a dual role in structural organization and maintaining electrostatic balance in the active site. The correct positioning of this residue in a catalytically competent conformation is provided by a functionally important conformational change in this enzyme and by the extensive network of H-bonding interactions that appear to be exquisitely preorganized for the transition state stabilization.

  • 13.
    Bauer, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Barrozo, Alexandre
    Department of Chemistry, University of Southern California, SGM 418, 3620 McClintock Ave., Los Angeles, CA 90089-1062, United StatesDepartment of Chemistry, University of Southern California, SGM 418, 3620 McClintock Ave., Los Angeles, CA 90089-1062, United States.
    Purg, Miha
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Amrein, Beat Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Esguerra, Mauricio
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Wilson, Philippe Barrie
    Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK.
    Major, Dan Thomas
    Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel.
    Åqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Q6: A comprehensive toolkit for empirical valence bond and related free energy calculations2018In: SoftwareX, ISSN 2352-7110, p. 388-395Article in journal (Refereed)
    Abstract [en]

    Atomistic simulations have become one of the main approaches to study the chemistry and dynamicsof biomolecular systems in solution. Chemical modelling is a powerful way to understand biochemistry,with a number of different programs available to perform specialized calculations. We present here Q6, anew version of the Q software package, which is a generalized package for empirical valence bond, linearinteraction energy, and other free energy calculations. In addition to general technical improvements, Q6extends the reach of the EVB implementation to fast approximations of quantum effects, extended solventdescriptions and quick estimation of the contributions of individual residues to changes in the activationfree energy of reactions.

  • 14.
    Bauer, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Janfalk Carlsson, Åsa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Amrein, Beat A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Dobritzsch, Doreen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kamerlin, S. C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Conformational Diversity and Enantioconvergence in Potato Epoxide Hydrolase 12016In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 14, no 24, p. 5639-5651Article in journal (Refereed)
    Abstract [en]

    Potato epoxide hydrolase 1 (StEH1) is a biocatalytically important enzyme that exhibits rich enantio-and regioselectivity in the hydrolysis of chiral epoxide substrates. In particular, StEH1 has been demonstrated to enantioconvergently hydrolyze racemic mixes of styrene oxide (SO) to yield (R)-1-phenylethanediol. This work combines computational, crystallographic and biochemical analyses to understand both the origins of the enantioconvergent behavior of the wild-type enzyme, as well as shifts in activities and substrate binding preferences in an engineered StEH1 variant, R-C1B1, which contains four active site substitutions (W106L, L109Y, V141K and I155V). Our calculations are able to reproduce both the enantio-and regioselectivities of StEH1, and demonstrate a clear link between different substrate binding modes and the corresponding selectivity, with the preferred binding modes being shifted between the wild-type enzyme and the R-C1B1 variant. Additionally, we demonstrate that the observed changes in selectivity and the corresponding enantioconvergent behavior are due to a combination of steric and electrostatic effects that modulate both the accessibility of the different carbon atoms to the nucleophilic side chain of D105, as well as the interactions between the substrate and protein amino acid side chains and active site water molecules. Being able to computationally predict such subtle effects for different substrate enantiomers, as well as to understand their origin and how they are affected by mutations, is an important advance towards the computational design of improved biocatalysts for enantioselective synthesis.

  • 15. Ben-David, Moshe
    et al.
    Sussman, Joel L.
    Maxwel, Christopher L.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Szeler, Klaudia
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Kamerlin, Lynn Shina C.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Tawfik, Dan S.
    Catalytic Stimulation by Restrained Active-Site Floppiness-The Case of High Density Lipoprotein-Bound Serum Paraoxonase-12015In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 427, no 6, p. 1359-1374Article in journal (Refereed)
    Abstract [en]

    Despite the abundance of membrane-associated enzymes, the mechanism by which membrane binding stabilizes these enzymes and stimulates their catalysis remains largely unknown. Serum paraoxonase-1 (PON1) is a lipophilic lactonase whose stability and enzymatic activity are dramatically stimulated when associated with high-density lipoprotein (HDL) particles. Our mutational and structural analyses, combined with empirical valence bond simulations, reveal a network of hydrogen bonds that connect HDL binding residues with Asn168-a key catalytic residue residing >15 angstrom from the HDL contacting interface. This network ensures precise alignment of N168, which, in turn, ligates PON1's catalytic calcium and aligns the lactone substrate for catalysis. HDL binding restrains the overall motion of the active site and particularly of N168, thus reducing the catalytic activation energy barrier. We demonstrate herein that disturbance of this network, even at its most far-reaching periphery, undermines PON1's activity. Membrane binding thus immobilizes long-range interactions via second- and third-shell residues that reduce the active site's floppiness and pre-organize the catalytic residues. Although this network is critical for efficient catalysis, as demonstrated here, unraveling these long-rage interaction networks is challenging, let alone their implementation in artificial enzyme design.

  • 16.
    Blaha-Nelson, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Krüger, Dennis M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Szeler, Klaudia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ben-David, Moshe
    Weizmann Inst Sci, Dept Biol Chem, IL-76100 Rehovot, Israel.;Univ Toronto, Banting & Best Dept Med Res, Donnelly Ctr Cellular & Biomol Res, 160 Coll St, Toronto, ON M5S 3E1, Canada..
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Active Site Hydrophobicity and the Convergent Evolution of Paraoxonase Activity in Structurally Divergent Enzymes: The Case of Serum Paraoxonase 12017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 3, p. 1155-1167Article in journal (Refereed)
    Abstract [en]

    Serum paraoxonase 1 (PON1) is a native lactonase capable of promiscuously hydrolyzing a broad range of substrates, including organophosphates, esters, and carbonates. Structurally, PON1 is a six-bladed beta-propeller with a flexible loop (residues 70-81) covering the active site. This loop contains a functionally critical Tyr at position 71. We have performed detailed experimental and computational analyses of the role of selected Y71 variants in the active site stability and catalytic activity in order to probe the role of Y71 in PON1's lactonase and organophosphatase activities. We demonstrate that the impact of Y71 substitutions on PON1's lactonase activity is minimal, whereas the k(cat) for the paraoxonase activity is negatively perturbed by up to 100-fold, suggesting greater mutational robustness of the native activity. Additionally, while these substitutions modulate PON1's active site shape, volume, and loop flexibility, their largest effect is in altering the solvent accessibility of the active site by expanding the active site volume, allowing additional water molecules to enter. This effect is markedly more pronounced in the organophosphatase activity than the lactonase activity. Finally, a detailed comparison of PON1 to other organophosphatases demonstrates that either a similar "gating loop" or a highly buried solvent excluding active site is a common feature of these enzymes. We therefore posit that modulating the active site hydrophobicity is a key element in facilitating the evolution of organophosphatase activity. This provides a concrete feature that can be utilized in the rational design of next-generation organophosphate hydrolases that are capable of selecting a specific reaction from a pool of viable substrates.

  • 17. Borstnar, Rok
    et al.
    Repic, Matej
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Vianello, Robert
    Mavri, Janez
    Computational Study of the pK(a) Values of Potential Catalytic Residues in the Active Site of Monoamine Oxidase B2012In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 8, no 10, p. 3864-3870Article in journal (Refereed)
    Abstract [en]

    Monoamine oxidase (MAO), which exists in two isozymic forms, MAO A and MAO B, is an important flavoenzyme responsible for the metabolism of amine neurotransmitters such as dopamine, serotonin, and norepinephrine. Despite extensive research effort, neither the catalytic nor the inhibition mechanisms of MAO have been completely understood. There has also been dispute with regard to the protonation state of the substrate upon entering the active site, as well as the identity of residues that are important for the initial deprotonation of irreversible acetylenic inhibitors, in accordance with the recently proposed mechanism. Therefore, in order to investigate features essential for the modes of action of MAO, we have calculated pK(a) values of three relevant tyrosine residues in the MAO B active site, with and without dopamine bound as the. substrate (as well as the pK(a) of the dopamine itself in the active site). The calculated pK(a) values for Tyr188, Tyr398, and Tyr435 in the complex are found to be shifted upward to 13.0, 13.7, and 14.7, respectively, relative to 10.1 in aqueous solution, ruling out the likelihood that they are viable proton acceptors. The altered tyrosine pK(a) values could be rationalized as an interplay of two opposing effects: insertion of positively charged bulky dopamine that lowers tyrosine pK(a) values, and subsequent removal of water molecules from the active site that elevates tyrosine pK(a) values, in which the latter prevails. Additionally, the pK(a) value of the bound dopamine (8.8) is practically unchanged compared to the corresponding value in aqueous solution (8.9), as would be expected from a charged amine placed in a hydrophobic active site consisting of aromatic moieties. We also observed potentially favorable cation-pi interactions between the -NH3+ group on dopamine and aromatic moieties, which provide a stabilizing effect to the charged fragment. Thus, we offer here theoretical evidence that the amine is most likely to be present in the active site in its protonated form, which is similar to the conclusion from experimental studies of MAO A (Jones et al. J. Neural Trans. 2007, 114, 707-712). However, the free energy cost of transferring the proton from the substrate to the bulk solvent is only 1.9 kcal mol(-1), leaving open the possibility that the amine enters the chemical step in its neutral form. In conjunction with additional experimental and computational work, the data presented here should lead toward a deeper understanding of mechanisms of the catalytic activity and irreversible inhibition of MAO B, which can allow for the design of novel and improved MAO B inhibitors.

  • 18.
    Braida, Benoit
    et al.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Theor, Cc 137-4,Pl Jussieu F, F-75252 Paris 05, France..
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Preface2017In: Computational and Theoretical Chemistry, ISSN 2210-271X, E-ISSN 2210-2728, Vol. 1116, no SI, p. 1-1Article in journal (Other academic)
    The full text will be freely available from 2020-01-01 15:17
  • 19.
    Carvalho, Alexandra T P
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Barrozo, Alexandre
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Doron, Dvir
    Kilshtain, Alexandra Vardi
    Major, Dan Thomas
    Kamerlin, Lynn Shina Caroline
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Challenges in computational studies of enzyme structure, function and dynamics2014In: Journal of Molecular Graphics and Modelling, ISSN 1093-3263, E-ISSN 1873-4243, Vol. 54, p. 62-79Article, review/survey (Refereed)
    Abstract [en]

    In this review we give an overview of the field of Computational enzymology. We start by describing the birth of the field, with emphasis on the work of the 2013 chemistry Nobel Laureates. We then present key features of the state-of-the-art in the field, showing what theory, accompanied by experiments, has taught us so far about enzymes. We also briefly describe computational methods, such as quantum mechanics-molecular mechanics approaches, reaction coordinate treatment, and free energy simulation approaches. We finalize by discussing open questions and challenges.

  • 20.
    Carvalho, Alexandra T. P.
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Gouveia, Leonor
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Vascular Biology.
    Kanna, Charan Raju
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Warmlander, Sebastian K. T. S.
    Platts, Jamie A.
    Kamerlin, Lynn Shina Caroline
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Understanding the structural and dynamic consequences of DNA epigenetic modifications: Computational insights into cytosine methylation and hydroxymethylation2014In: Epigenetics, ISSN 1559-2294, E-ISSN 1559-2308, Vol. 9, no 12, p. 1604-1612Article in journal (Refereed)
    Abstract [en]

    We report a series of molecular dynamics (MD) simulations of up to a microsecond combined simulation time designed to probe epigenetically modified DNA sequences. More specifically, by monitoring the effects of methylation and hydroxymethylation of cytosine in different DNA sequences, we show, for the first time, that DNA epigenetic modifications change the molecule's dynamical landscape, increasing the propensity of DNA toward different values of twist and/or roll/tilt angles (in relation to the unmodified DNA) at the modification sites. Moreover, both the extent and position of different modifications have significant effects on the amount of structural variation observed. We propose that these conformational differences, which are dependent on the sequence environment, can provide specificity for protein binding.

  • 21.
    Carvalho, Alexandra T. P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    O'Donoghue, AnnMarie C.
    Hodgson, David R. W.
    Kamerlin, Shina C. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Understanding thio-effects in simple phosphoryl systems: role of solvent effects and nucleophile charge2015In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 13, no 19, p. 5391-5398Article in journal (Refereed)
    Abstract [en]

    Recent experimental work (J. Org. Chem., 2012, 77, 5829) demonstrated pronounced differences in measured thio-effects for the hydrolysis of (thio) phosphodichloridates by water and hydroxide nucleophiles. In the present work, we have performed detailed quantum chemical calculations of these reactions, with the aim of rationalizing the molecular bases for this discrimination. The calculations highlight the interplay between nucleophile charge and transition state solvation in S(N)2(P) mechanisms as the basis of these differences, rather than a change in mechanism.

  • 22.
    Carvalho, Alexandra T. P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Szeler, Klaudia
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Vavitsas, Konstantinos
    Univ Copenhagen, Dept Plant & Environm Sci, CPSC, DK-1871 Frederiksberg C, Denmark..
    Åqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamerlin, Lynn Shina C.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Modeling the mechanisms of biological GTP hydrolysis2015In: Archives of Biochemistry and Biophysics, ISSN 0003-9861, E-ISSN 1096-0384, Vol. 582, no SI, p. 80-90Article, review/survey (Refereed)
    Abstract [en]

    Enzymes that hydrolyze GTP are currently in the spotlight, due to their molecular switch mechanism that controls many cellular processes. One of the best-known classes of these enzymes are small GTPases such as members of the Ras superfamily, which catalyze the hydrolysis of the gamma-phosphate bond in GTP. In addition, the availability of an increasing number of crystal structures of translational GTPases such as EF-Tu and EF-G have made it possible to probe the molecular details of GTP hydrolysis on the ribosome. However, despite a wealth of biochemical, structural and computational data, the way in which GTP hydrolysis is activated and regulated is still a controversial topic and well-designed simulations can play an important role in resolving and rationalizing the experimental data. In this review, we discuss the contributions of computational biology to our understanding of GTP hydrolysis on the ribosome and in small GTPases.

  • 23.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Amrein, Beat A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Blaha-Nelson, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Recent advances in QM/MM free energy calculations using reference potentials2015In: Biochimica et Biophysica Acta - General Subjects, ISSN 0304-4165, E-ISSN 1872-8006, Vol. 1850, no 5, p. 954-965Article, review/survey (Refereed)
    Abstract [en]

    Background: Recent years have seen enormous progress in the development of methods for modeling (bio)molecular systems. This has allowed for the simulation of ever larger and more complex systems. However, as such complexity increases, the requirements needed for these models to be accurate and physically meaningful become more and more difficult to fulfill. The use of simplified models to describe complex biological systems has long been shown to be an effective way to overcome some of the limitations associated with this computational cost in a rational way. Scope of review: Hybrid QM/MM approaches have rapidly become one of the most popular computational tools for studying chemical reactivity in biomolecular systems. However, the high cost involved in performing high-level QM calculations has limited the applicability of these approaches when calculating free energies of chemical processes. In this review, we present some of the advances in using reference potentials and mean field approximations to accelerate high-level QM/MM calculations. We present illustrative applications of these approaches and discuss challenges and future perspectives for the field. Major conclusions: The use of physically-based simplifications has shown to effectively reduce the cost of high-level QM/MM calculations. In particular, lower-level reference potentials enable one to reduce the cost of expensive free energy calculations, thus expanding the scope of problems that can be addressed. General significance: As was already demonstrated 40 years ago, the usage of simplified models still allows one to obtain cutting edge results with substantially reduced computational cost. This article is part of a Special Issue entitled Recent developments of molecular dynamics.

  • 24.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Amrein, Beat Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Kamerlin, Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Modeling catalytic promiscuity in the alkaline phosphatase superfamily2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 27, p. 11160-11177Article in journal (Refereed)
    Abstract [en]

    In recent years, it has become increasingly clear that promiscuity plays a key role in the evolution of new enzyme function. This finding has helped to elucidate fundamental aspects of molecular evolution. While there has been extensive experimental work on enzyme promiscuity, computational modeling of the chemical details of such promiscuity has traditionally fallen behind the advances in experimental studies, not least due to the nearly prohibitive computational cost involved in examining multiple substrates with multiple potential mechanisms and binding modes in atomic detail with a reasonable degree of accuracy. However, recent advances in both computational methodologies and power have allowed us to reach a stage in the field where we can start to overcome this problem, and molecular simulations can now provide accurate and efficient descriptions of complex biological systems with substantially less computational cost. This has led to significant advances in our understanding of enzyme function and evolution in a broader sense. Here, we will discuss currently available computational approaches that can allow us to probe the underlying molecular basis for enzyme specificity and selectivity, discussing the inherent strengths and weaknesses of each approach. As a case study, we will discuss recent computational work on different members of the alkaline phosphatase superfamily (AP) using a range of different approaches, showing the complementary insights they have provided. We have selected this particular superfamily, as it poses a number of significant challenges for theory, ranging from the complexity of the actual reaction mechanisms involved to the reliable modeling of the catalytic metal centers, as well as the very large system sizes. We will demonstrate that, through current advances in methodologies, computational tools can provide significant insight into the molecular basis for catalytic promiscuity, and, therefore, in turn, the mechanisms of protein functional evolution.

  • 25.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Barrozo, Alexandre
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Amrein, Beat Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Purg, Miha
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Åqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Force Field Independent Metal Parameters Using a Nonbonded Dummy Model2014In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, no 16, p. 4351-4362Article in journal (Refereed)
    Abstract [en]

    The cationic dummy atom approach provides a powerful nonbonded description for a range of alkaline-earth and transition-metal centers, capturing both structural and electrostatic effects. In this work we refine existing literature parameters for octahedrally coordinated Mn2+, Zn2+, Mg2+, and Ca2+, as well as providing new parameters for Ni2+, Co2+, and Fe2+. In all the cases, we are able to reproduce both M2+-O distances and experimental solvation free energies, which has not been achieved to date for transition metals using any other model. The parameters have also been tested using two different water models and show consistent performance. Therefore, our parameters are easily transferable to any force field that describes nonbonded interactions using Coulomb and Lennard-Jones potentials. Finally, we demonstrate the stability of our parameters in both the human and Escherichia coli variants of the enzyme glyoxalase 1 as showcase systems, as both enzymes are active with a range of transition metals. The parameters presented in this work provide a valuable resource for the molecular simulation community, as they extend the range of metal ions that can be studied using classical approaches, while also providing a starting point for subsequent parametrization of new metal centers.

  • 26.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Geng, Ting
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Marloie, Gaël
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Al Hussain, Adel O.
    Williams, Nicholas H.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 7, p. 2816-2828Article in journal (Refereed)
    Abstract [en]

    Sulfonate ester hydrolysis has been the subject of recent debate, with experimental evidence interpreted in terms of both stepwise and concerted mechanisms. In particular, a recent study of the alkaline hydrolysis of a series of benzene arylsulfonates (Babtie et al., Org. Biomol. Chem. 10, 2012, 8095) presented a nonlinear Bronsted plot, which was explained in terms of a change from a stepwise mechanism involving a pentavalent intermediate for poorer leaving groups to a fully concerted mechanism for good leaving groups and supported by a theoretical study. In the present work, we have performed a detailed computational study of the hydrolysis of these compounds and find no computational evidence for a thermodynamically stable intermediate for any of these compounds. Additionally, we have extended the experimental data to include pyridine-3-yl benzene sulfonate and its N-oxide and N-methylpyridinium derivatives. Inclusion of these compounds converts the Bronsted plot to a moderately scattered but linear correlation and gives a very good Hammett correlation. These data suggest a concerted pathway for this reaction that proceeds via an early transition state with little bond cleavage to the leaving group, highlighting the care that needs to be taken with the interpretation of experimental and especially theoretical data.

  • 27.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Gronert, Scott
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Concerted or Stepwise: How Much Do Free-Energy Landscapes Tell Us about the Mechanisms of Elimination Reactions?2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 3, p. 1280-1288Article in journal (Refereed)
    Abstract [en]

    The base-catalyzed dehydration of benzene cis-1,2-dihydrodiols is driven by formation of an aromatic product as well as intermediates potentially stabilized by hyperaromaticity. Experiments exhibit surprising shifts in isotope effects, indicating an unusual mechanistic balance on the E2-E1cB continuum. In this study, both land 2-dimensional free energy surfaces are generated for these compounds with various substituents, using density functional theory and a mixed implicit/explicit solvation model. The computational data help unravel hidden intermediates along the reaction coordinate and provide a novel conceptual framework for distinguishing between competing pathways in this and any other system with borderline reaction mechanisms.

  • 28.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Rationalizing the Catalytic Activity of an Unusual Oxidoreductase (FucO)2013In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 104, no 2, p. 495A-495AArticle in journal (Other academic)
  • 29.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Åqvist, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Williams, Nicholas H
    Kamerlin, Shina C Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Resolving apparent conflicts between theoretical and experimental models of phosphate monoester hydrolysis.2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 3, p. 1081-93Article in journal (Refereed)
    Abstract [en]

    Understanding phosphoryl and sulfuryl transfer is central to many biochemical processes. However, despite decades of experimental and computational studies, a consensus concerning the precise mechanistic details of these reactions has yet to be reached. In this work we perform a detailed comparative theoretical study of the hydrolysis of p-nitrophenyl phosphate, methyl phosphate and p-nitrophenyl sulfate, all of which have served as key model systems for understanding phosphoryl and sulfuryl transfer reactions, respectively. We demonstrate the existence of energetically similar but mechanistically distinct possibilities for phosphate monoester hydrolysis. The calculated kinetic isotope effects for p-nitrophenyl phosphate provide a means to discriminate between substrate- and solvent-assisted pathways of phosphate monoester hydrolysis, and show that the solvent-assisted pathway dominates in solution. This preferred mechanism for p-nitrophenyl phosphate hydrolysis is difficult to find computationally due to the limitations of compressing multiple bonding changes onto a 2-dimensional energy surface. This problem is compounded by the need to include implicit solvation to at least microsolvate the system and stabilize the highly charged species. In contrast, methyl phosphate hydrolysis shows a preference for a substrate-assisted mechanism. For p-nitrophenyl sulfate hydrolysis there is only one viable reaction pathway, which is similar to the solvent-assisted pathway for phosphate hydrolysis, and the substrate-assisted pathway is not accessible. Overall, our results provide a unifying mechanistic framework that is consistent with the experimentally measured kinetic isotope effects and reconciles the discrepancies between theoretical and experimental models for these biochemically ubiquitous classes of reaction.

  • 30.
    Holbrook, J. Britt
    et al.
    New Jersey Inst Technol, Newark, NJ 07102 USA.
    Curry, Stephen
    Imperial Coll, London, England.
    Kamerlin, Shina C. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Debate on academic freedom and open access is healthy2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 562, no 7728, p. 494-494Article in journal (Other academic)
  • 31.
    Hong, Nan-Sook
    et al.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Petrovic, Dusan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Lee, Richmond
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Gryn'ova, Ganna
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia;Ecole Polytech Fed Lausanne, Inst Sci & Ingn Chim, CH-1015 Lausanne, Switzerland.
    Purg, Miha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Saunders, Jake
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Carr, Paul D.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Lin, Ching-Yeh
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Mabbitt, Peter D.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Zhang, William
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Altamore, Timothy
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Easton, Chris
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Coote, Michelle L.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Jackson, Colin J.
    Australian Natl Univ, Res Sch Chem, Canberra, ACT 2601, Australia.
    The evolution of multiple active site configurations in a designed enzyme2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 3900Article in journal (Refereed)
    Abstract [en]

    Developments in computational chemistry, bioinformatics, and laboratory evolution have facilitated the de novo design and catalytic optimization of enzymes. Besides creating useful catalysts, the generation and iterative improvement of designed enzymes can provide valuable insight into the interplay between the many phenomena that have been suggested to contribute to catalysis. In this work, we follow changes in conformational sampling, electrostatic preorganization, and quantum tunneling along the evolutionary trajectory of a designed Kemp eliminase. We observe that in the Kemp Eliminase KE07, instability of the designed active site leads to the emergence of two additional active site configurations. Evolutionary conformational selection then gradually stabilizes the most efficient configuration, leading to an improved enzyme. This work exemplifies the link between conformational plasticity and evolvability and demonstrates that residues remote from the active sites of enzymes play crucial roles in controlling and shaping the active site for efficient catalysis.

  • 32.
    Janfalk Carlsson, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Dobritzsch, Doreen
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kamerlin, Shina C Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Epoxide Hydrolysis as a Model System for Understanding Flux Through a Branched Reaction Scheme2018In: IUCrJ, ISSN 0972-6918, E-ISSN 2052-2525, Vol. 5, no 3, p. 269-282Article in journal (Refereed)
    Abstract [en]

    The epoxide hydrolase StEH1 catalyzes the hydrolysis of trans-methylstyrene oxide to 1-phenyl­propane-1,2-diol. The (S,S)-epoxide is exclusively transformed into the (1R,2S)-diol, while hydrolysis of the (R,R)-epoxide results in a mixture of product enantiomers. In order to understand the differences in the stereoconfigurations of the products, the reactions were studied kinetically during both the pre-steady-state and steady-state phases. A number of closely related StEH1 variants were analyzed in parallel, and the results were rationalized by structure–activity analysis using the available crystal structures of all tested enzyme variants. Finally, empirical valence-bond simulations were performed in order to provide additional insight into the observed kinetic behaviour and ratios of the diol product enantiomers. These combined data allow us to present a model for the flux through the catalyzed reactions. With the (R,R)-epoxide, ring opening may occur at either C atom and with similar energy barriers for hydrolysis, resulting in a mixture of diol enantiomer products. However, with the (S,S)-epoxide, although either epoxide C atom may react to form the covalent enzyme intermediate, only the pro-(R,S) alkylenzyme is amenable to subsequent hydrolysis. Previously contradictory observations from kinetics experiments as well as product ratios can therefore now be explained for this biocatalytically relevant enzyme.

  • 33.
    Kaltenbach, Miriam
    et al.
    Weizmann Inst Sci, Dept Biol Chem, Rehovot, Israel.
    Burke, Jason R.
    Salk Inst Biol Studies, Howard Hughes Med Inst, Jack H Skirball Ctr Chem Biol & Prote, La Jolla, CA 92037 USA.
    Dindo, Mirco
    Weizmann Inst Sci, Dept Biol Chem, Rehovot, Israel;Univ Verona, Biol Chem Sect, Dept Neurosci Biomed & Movement Sci, Verona, Italy.
    Pabis, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Steffen-Munsberg, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Rabin, Avigayel
    Weizmann Inst Sci, Dept Biol Chem, Rehovot, Israel;Hebrew Univ Jerusalem, Alexander Silberman Inst Life Sci, Dept Biol Chem, Edmond J Safra Campus, Jerusalem, Israel.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Noel, Joseph P.
    Salk Inst Biol Studies, Howard Hughes Med Inst, Jack H Skirball Ctr Chem Biol & Prote, La Jolla, CA 92037 USA.
    Tawfik, Dan S.
    Weizmann Inst Sci, Dept Biol Chem, Rehovot, Israel.
    Evolution of chalcone isomerase from a noncatalytic ancestor2018In: Nature Chemical Biology, ISSN 1552-4450, E-ISSN 1552-4469, Vol. 14, no 6, p. 548-555Article in journal (Refereed)
    Abstract [en]

    The emergence of catalysis in a noncatalytic protein scaffold is a rare, unexplored event. Chalcone isomerase (CHI), a key enzyme in plant flavonoid biosynthesis, is presumed to have evolved from a nonenzymatic ancestor related to the widely distributed fatty-acid binding proteins (FAPs) and a plant protein family with no isomerase activity (CHILs). Ancestral inference supported the evolution of CHI from a protein lacking isomerase activity. Further, we identified four alternative founder mutations, i.e., mutations that individually instated activity, including a mutation that is not phylogenetically traceable. Despite strong epistasis in other cases of protein evolution, CHI's laboratory reconstructed mutational trajectory shows weak epistasis. Thus, enantioselective CHI activity could readily emerge despite a catalytically inactive starting point. Accordingly, X-ray crystallography, NMR, and molecular dynamics simulations reveal reshaping of the active site toward a productive substratebinding mode and repositioning of the catalytic arginine that was inherited from the ancestral fatty-acid binding proteins.

  • 34.
    Kamerlin, Shina Caroline Lynn
    Stockholm University, Department of Organic Chemistry, Arrhenius Laboratory.
    Theoretical comparison of p-nitrophenyl phosphate and sulfate hydrolysis in aqueous solution: implications for enzyme-catalyzed sulfuryl transfer2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 22, p. 9228-9238Article in journal (Refereed)
    Abstract [en]

    Both phosphoryl and sulfuryl transfers are ubiquitous in biology, being involved in a wide range of processes, ranging from cell division to apoptosis. Additionally, it is becoming increasingly clear that enzymes that can catalyze phosphoryl transfer can often cross-catalyze sulfuryl transfer (and vice versa). However, while there have been extensive experimental and theoretical studies performed on phosphoryl transfer, the body of available research on sulfuryl transfer is comparatively much smaller. The present work presents a direct theoretical comparison of p-nitrophenyl phosphate and sulfate monoester hydrolysis, both of which are considered prototype systems for probing phosphoryl and sulfuryl transfer, respectively. Specifically, free energy surfaces have been generated using density functional theory, by initial geometry optimization in PCM using the 6-31+G* basis set and the B3LYP density functional, followed by single-point calculations using the larger 6-311+G** basis set and the COSMO continuum model. The resulting surfaces have been then used to identify the relevant transition states, either by further unconstrained geometry optimization or from the surface itself where possible. Additionally, configurational entropies were evaluated using a combination of the quasiharmonic approximation and the restraint release approach and added to the calculated activation barriers as a correction. Finally, the overall activation entropy was estimated by approximating the solvent contribution to the total activation entropy using the Langevin dipoles solvation model. We have reproduced both the experimentally observed activation barriers and the observed trend in the activation entropies with reasonable accuracy, as well as providing a comparison of calculated and observed (15)N and (18)O kinetic isotope effects. We demonstrate that, counterintuitively, the hydrolysis of the p-nitrophenyl sulfate proceeds through a more expansive pathway than its phosphate analogue. Additionally, we show that the solvation effects upon moving from the ground state to the transition state are quite different for both reactions, suggesting that the enzymes that catalyze these reactions would need active sites with quite different electrostatic preorganization for the efficient catalysis of either reaction (despite which many enzymes can catalyze both phosphoryl and sulfuryl transfer). We believe that such a comparative study is an important foundation for understanding the molecular basis for phosphate-sulfate cross-promiscuity within members of the alkaline phosphatase superfamily.

  • 35.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Where are the female science professors? A personal perspective2016In: F1000 Research, E-ISSN 2046-1402, Vol. 5, article id 1224Article in journal (Refereed)
    Abstract [en]

    The first woman to earn a Professorship at a University in Europe was Laura Maria Caterina Bassi, who earned a professorship in physics at the University of Bologna in 1732. Almost 300 years and three waves of feminism later, in 2016, women typically still only comprise 20% (or less) of the number of full professors in Europe. This opinion article will discuss the experiences of being a female academic today and the factors contributing to the academic gender gap from the perspective of a “young” natural scientist, as well as providing constructive suggestions for strategies to empower women in the academic world.

  • 36.
    Kamerlin, Shina Caroline Lynn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Sharma, Pankaz
    Prasad, Ram
    Warshel, Arieh
    Why nature really chose phosphate2013In: Quarterly reviews of biophysics (Print), ISSN 0033-5835, E-ISSN 1469-8994, Vol. 46, no 1, p. 1-132Article in journal (Refereed)
    Abstract [en]

    Phosphoryl transfer plays key roles in signaling, energy transduction, protein synthesis, and maintaining the integrity of the genetic material. On the surface, it would appear to be a simple nucleophile displacement reaction. However, this simplicity is deceptive, as, even in aqueous solution, the low-lying d-orbitals on the phosphorus atom allow for eight distinct mechanistic possibilities, before even introducing the complexities of the enzyme catalyzed reactions. To further complicate matters, while powerful, traditional experimental techniques such as the use of linear free-energy relationships (LFER) or measuring isotope effects cannot make unique distinctions between different potential mechanisms. A quarter of a century has passed since Westheimer wrote his seminal review, ‘Why Nature Chose Phosphate’ (Science 235 (1987), 1173), and a lot has changed in the field since then. The present review revisits this biologically crucial issue, exploring both relevant enzymatic systems as well as the corresponding chemistry in aqueous solution, and demonstrating that the only way key questions in this field are likely to be resolved is through careful theoretical studies (which of course should be able to reproduce all relevant experimental data). Finally, we demonstrate that the reason that nature really chose phosphate is due to interplay between two counteracting effects: on the one hand, phosphates are negatively charged and the resulting charge-charge repulsion with the attacking nucleophile contributes to the very high barrier for hydrolysis, making phosphate esters among the most inert compounds known. However, biology is not only about reducing the barrier to unfavorable chemical reactions. That is, the same charge-charge repulsion that makes phosphate ester hydrolysis so unfavorable also makes it possible to regulate, by exploiting the electrostatics. This means that phosphate ester hydrolysis can not only be turned on, but also be turned off, by fine tuning the electrostatic environment and the present review demonstrates numerous examples where this is the case. Without this capacity for regulation, it would be impossible to have for instance a signaling or metabolic cascade, where the action of each participant is determined by the fine-tuned activity of the previous piece in the production line. This makes phosphate esters the ideal compounds to facilitate life as we know it.

  • 37.
    Krüger, Dennis M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Micelle Maker: An Online Tool for Generating Equilibrated Micelles as Direct Input for Molecular Dynamics Simulations2017In: ACS OMEGA, ISSN 2470-1343, Vol. 2, no 8, p. 4524-4530Article in journal (Refereed)
    Abstract [en]

    Micelles play an important role in both experimental and computational studies of the effect of lipid interactions on biological systems. The spherical geometry and the dynamical behavior of micelles makes generating micelle structures for use in molecular simulations challenging. An easy tool for generating simulation-ready micelle models, covering a broad range of lipids, is highly desirable. Here, we present a new Web server, Micelle Maker, which can provide equilibrated micelle models as a direct input for subsequent molecular dynamics simulations from a broad range of lipids (currently 25 lipid types, including 24 glycolipids). The Web server, which is available at http:// www. micellemaker. net, uses error checking routines to prevent clashes during the initial placement of the lipids and uses AMBER's GLYCAM library for generating minimized or equilibrated micelle models, but the resulting structures can be used as starting points for simulations with any force field or simulation package. Extensive validation simulations with an overall simulation time of 12 mu s using eight micelle models where assembly information is available show that all of the micelles remain very stable over the whole simulation time. Finally, we discuss the advantages of Micelle Maker relative to other approaches in the field.

  • 38. Kudavalli, Jaya Satyanarayana
    et al.
    Rao, S. Nagaraja
    Bean, David E.
    Sharma, Narain D.
    Boyd, Derek R.
    Fowler, Patrick W.
    Gronert, Scott
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Keeffe, James R.
    O'Ferrall, Rory A. More
    Base-Catalyzed Dehydration of 3-Substituted Benzene cis-1,2-Dihydrodiols: Stabilization of a Cyclohexadienide Anion Intermediate by Negative Aromatic Hyperconjugation2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 34, p. 14056-14069Article in journal (Refereed)
    Abstract [en]

    Evidence that a 1,2-dihydroxycyclohexadienide anion is stabilized by aromatic "negative hyperconjugation" is described. It complements an earlier inference of "positive" hyperconjugative aromaticity for the cyclohexadienyl cation. The anion is a reactive intermediate in the dehydration of benzene cis-1,2-dihydrodiol to phenol. Rate constants for 3-substituted benzene cis-dihydrodiols are correlated by values with rho = 3.2. Solvent isotope effects for the reactions are k(H2O)/k(D2O) = 1.2-1.8. These measurements are consistent with reaction via a carbanion intermediate or a concerted reaction with a "carbanion-like" transition state. These and other experimental results confirm that the reaction proceeds by a stepwise mechanism, with a change in rate-determining step from proton transfer to the loss of hydroxide ion from the intermediate. Hydrogen isotope exchange accompanying dehydration of the parent benzene cis-1,2-dihydrodiol was not found, and thus, the proton transfer step is subject to internal return. A rate constant of similar to 10(11) s(-1), corresponding to rotational relaxation of the aqueous solvent, is assigned to loss of hydroxide ion from the intermediate. The rate constant for internal return therefore falls in the range 10(11)-10(12) s(-1). From these limiting values and the measured rate constant for hydroxide-catalyzed dehydration, a pK(a) of 30.8 +/- 0.5 was determined for formation of the anion. Although loss of hydroxide ion is hugely exothermic, a concerted reaction is not enforced by the instability of the intermediate. Stabilization by negative hyperconjugation is proposed for 1,2-dihydroxycyclohexadienide and similar anions, and this proposal is supported by additional experimental evidence and by computational results, including evidence for a diatropic ("aromatic") ring current in 3,3-difluorocyclohexadienyl anion.

  • 39.
    Kulkarni, Yashraj S.
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Liao, Qinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bylehn, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab. UCL, Dept Chem Engn, Torrington Pl, London WC1E 7JE, England.
    Amyes, Tina L.
    SUNY Buffalo, Dept Chem, Buffalo, NY 14260 USA.
    Richard, John P.
    SUNY Buffalo, Dept Chem, Buffalo, NY 14260 USA.
    Kamerlin, Shina C. Lynn
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Role of Ligand-Driven Conformational Changes in Enzyme Catalysis: Modeling the Reactivity of the Catalytic Cage of Triosephosphate Isomerase2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 11, p. 3854-3857Article in journal (Refereed)
    Abstract [en]

    We have previously performed empirical valence bond calculations of the kinetic activation barriers, Delta G(calc) double dagger, for the deprotonation of complexes between TIM and the whole substrate glyceraldehyde-3-phosphate (GAP, Kulkarni et al. J. Am. Chem. Soc. 2017, 139, 10514-10525). We now extend this work to also study the deprotonation of the substrate pieces glycolaldehyde (GA) and GA.HPi [HPi = phosphite dianion]. Our combined calculations provide activation barriers, Delta G(calc)(double dagger) for the TIM-catalyzed deprotonation of GAP (12.9 +/- 0.8 kcal.mol(-1)), of the substrate piece GA (15.0 +/- 2.4 kcal.mol(-1)), and of the pieces GA.HP, (15.5 +/- 3.5 kcal.mol(-1)). The effect of bound dianion on Delta G(calc) double dagger is small (<= 2.6 kcal.mol(-1)), in comparison to the much larger 12.0 and 5.8 kcal.mol(-1) intrinsic phosphodianion and phosphite dianion binding energy utilized to stabilize the transition states for TIM-catalyzed deprotonation of GAP and GA. HP, respectively. This shows that the dianion binding energy is essentially fully expressed at our protein model for the Michaelis complex, where it is utilized to drive an activating change in enzyme conformation. The results represent an example of the synergistic use of results from experiments and calculations to advance our understanding of enzymatic reaction mechanisms.

  • 40.
    Kulkarni, Yashraj S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Liao, Qinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Petrovic, Dusan
    Forschungszentrum Julich, Inst Complex Syst Struct Biochem, D-52425 Julich, Germany..
    Krüger, Dennis M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Strodel, Birgit
    Forschungszentrum Julich, Inst Complex Syst Struct Biochem, D-52425 Julich, Germany.;Heinrich Heine Univ Dusseldorf, Inst Theoret & Computat Chem, Univ Str 1, D-40225 Dusseldorf, Germany..
    Amyes, Tina L.
    SUNY Buffalo, Dept Chem, Buffalo, NY 14260 USA..
    Richard, John P.
    SUNY Buffalo, Dept Chem, Buffalo, NY 14260 USA..
    Kamerlin, Shina C. L.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Enzyme Architecture: Modeling the Operation of a Hydrophobic Clamp in Catalysis by Triosephosphate Isomerase2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 30, p. 10514-10525Article in journal (Refereed)
    Abstract [en]

    Triosephosphate isomerase (TIM) is a proficient catalyst of the reversible isomerization of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde phosphate (GAP), via general base catalysis by E165. Historically, this enzyme has been an extremely important model system for understanding the fundamentals of biological catalysis. TIM is activated through an energetically demanding conformational change, which helps position the side chains of two key hydrophobic residues (1170 and L230), over the carboxylate side chain of E165. This is critical both for creating a hydrophobic pocket for the catalytic base and for maintaining correct active site architecture. Truncation of these residues to alanine causes significant falloffs in TIM's catalytic activity, but experiments have failed to provide a full description of the action of this clamp in promoting substrate deprotonation. We perform here detailed empirical valence bond calculations of the TIM-catalyzed deprotonation of DHAP and GAP by both wild type TIM and its 1170A, L230A, and 1170A/L230A mutants, obtaining exceptional quantitative agreement with experiment. Our calculations provide a linear free energy relationship, with slope 0.8, between the activation barriers and Gibbs free energies for these TIM-catalyzed reactions. We conclude that these clamping side chains minimize the Gibbs free energy for substrate deprotonation, and that the effects on reaction driving force are largely expressed at the transition state for proton transfer. Our combined analysis of previous experimental and current computational results allows us to provide an overview of the breakdown of ground-state and transition state effects in enzyme catalysis in unprecedented detail, providing a molecular description of the operation of a hydrophobic clamp in triosephosphate isomerase.

  • 41. Liao, Qinghua
    et al.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Strodel, Birgit
    Development and Application of a Nonbonded Cu2+ Model That Includes the Jahn-Teller Effect2015In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 6, no 13, p. 2657-2662Article in journal (Refereed)
    Abstract [en]

    Metal ions are both ubiquitous to and crucial in biology. In classical simulations, they are typically described as simple van der Waals spheres, making it difficult to provide reliable force field descriptions for them. An alternative is given by nonbonded dummy models, in which the central metal atom is surrounded by dummy particles that each carry a partial charge. While such dummy models already exist for other metal ions, none is available yet for Cu2+ because of the challenge to reproduce the Jahn-Teller distortion. This challenge is addressed in the current study, where, for the first time, a dummy model including a Jahn-Teller effect is developed for Cu2+. We successfully validate its usefulness by studying metal binding in two biological systems: the amyloid-beta peptide and the mixed-metal enzyme superoxide dismutase. We believe that our parameters will be of significant value for the computational study of Cu2+'-dependent biological systems using classical models.

  • 42.
    Liao, Qinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Kulkarni, Yashraj
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Sengupta, Ushnish
    Forschungszentrum Jülich, Germany.
    Petrovic, Dusan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Mulholland, Adrian J.
    University of Bristol, United Kingdom.
    van der Kamp, Marc W.
    University of Bristol, United Kingdom.
    Strodel, Birgit
    Forschungszentrum Jülich, Germany.
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Loop Motion in Triosephosphate Isomerase Is Not a Simple Open and Shut Case2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 46, p. 15889-15903Article in journal (Refereed)
    Abstract [en]

    Conformational changes are crucial for the catalytic action of many enzymes. A prototypical and well-studied example is loop opening and closure in triosephosphate isomerase (TIM), which is thought to determine the rate of catalytic turnover in many circumstances. Specifically, TIM loop 6 “grips” the phosphodianion of the substrate and, together with a change in loop 7, sets up the TIM active site for efficient catalysis. Crystal structures of TIM typically show an open or a closed conformation of loop 6, with the tip of the loop moving ∼7 Å between conformations. Many studies have interpreted this motion as a two-state, rigid-body transition. Here, we use extensive molecular dynamics simulations, with both conventional and enhanced sampling techniques, to analyze loop motion in apo and substrate-bound TIM in detail, using five crystal structures of the dimeric TIM from Saccharomyces cerevisiae. We find that loop 6 is highly flexible and samples multiple conformational states. Empirical valence bond simulations of the first reaction step show that slight displacements away from the fully closed-loop conformation can be sufficient to abolish most of the catalytic activity; full closure is required for efficient reaction. The conformational change of the loops in TIM is thus not a simple “open and shut” case and is crucial for its catalytic action. Our detailed analysis of loop motion in a highly efficient enzyme highlights the complexity of loop conformational changes and their role in biological catalysis.

  • 43.
    Liao, Qinghua
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Lüking, Malin
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Krueger, Dennis M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab. German Ctr Neurodegenerat Dis, Bioinformat Unit, Dept Epigenet & Syst Med Neurodegenerat Dis, Siebold Str 3A, D-37075 Gottingen, Germany.
    Deindl, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Elf, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kasson, Peter M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Long Time-Scale Atomistic Simulations of the Structure and Dynamics of Transcription Factor-DNA Recognition2019In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 123, no 17, p. 3576-3590Article in journal (Refereed)
    Abstract [en]

    Recent years have witnessed an explosion of interest in computational studies of DNA binding proteins, including both coarse grained and atomistic simulations of transcription factor-DNA recognition, to understand how these transcription factors recognize their binding sites on the DNA with such exquisite specificity. The present study performs microsecond time scale all-atom simulations of the dimeric form of the lactose repressor (Lad), both in the absence of any DNA and in the presence of both specific and nonspecific complexes, considering three different DNA sequences. We examine, specifically, the conformational differences between specific and nonspecific protein DNA interactions, as well as the behavior of the helix-turn-helix motif of Lad when interacting with the DNA. Our simulations suggest that stable Lad binding occurs primarily to bent A-form DNA, with a loss of Lad conformational entropy and optimization of correlated conformational equilibria across the protein. In addition, binding to the specific operator sequence involves a slightly larger number of stabilizing DNA protein hydrogen bonds (in comparison to nonspecific complexes), which may account for the experimentally observed specificity for this operator. In doing so, our simulations provide a detailed atomistic description of potential structural drivers for LacI selectivity.

  • 44.
    Liao, Qinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Pabis, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Strodel, Birgit
    Forschungszentrum Julich, Julich, Germany; Heinrich Heine Univ Dusseldorf, Dusseldorf, Germany.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Extending the Nonbonded Cationic Dummy Model to Account for Ion-Induced Dipole Interactions2017In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 8, no 21, p. 5408-5414Article in journal (Refereed)
    Abstract [en]

    Modeling metalloproteins often requires classical molecular dynamics (MD) simulations in order to capture their relevant motions, which in turn necessitates reliable descriptions of the metal centers involved. One of the most successful approaches to date is provided by the "cationic dummy model", where the positive charge of the metal ion is transferred toward dummy particles that are bonded to the central metal ion in a predefined coordination geometry. While this approach allows for ligand exchange, and captures the correct electrostatics as demonstrated for different divalent metal ions, current dummy models neglect ion-induced dipole interactions. In the present work, we resolve this weakness by taking advantage of the recently introduced 12-6-4 type Lennard-Jones potential to include ion-induced dipole interactions. We revise our previous dummy model for Mg2+ and demonstrate that the resulting model can simultaneously reproduce the experimental solvation free energy and metal ligand distances without the need for artificial restraints or bonds. As ion-induced dipole interactions become particularly important for highly charged metal ions, we develop dummy models for the biologically relevant ions Al3+, Fe3+, and Cr3+. Finally, the effectiveness of our new models is demonstrated in MD simulations of several diverse (and highly challenging to simulate) metalloproteins.

  • 45.
    Luo, Jinghui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Biophysical Structural Chemistry, University of Leiden.
    van Loo, Bert
    University of Cambridge, Department of Biochemistry.
    Kamerlin, Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Examining the promiscuous phosphatase activity of Pseudomonas aeruginosa arylsulfatase: A comparison to analogous phosphatases2012In: Proteins: Structure, Function and Bioinformatics, ISSN 1097-0134, Vol. 80, no 4, p. 1211-1226Article in journal (Refereed)
    Abstract [en]

    Pseudomonas aeruginosa arylsulfatase (PAS) is a bacterial sulfatase capable ofhydrolyzing a range of sulfate esters. Recently, it has been demonstrated to also show very high proficiency for phosphate ester hydrolysis. Such proficient catalytic promiscuity is significant, as promiscuity has been suggested to play an important role in enzyme evolution. Additionally, a comparative study of the hydrolyses of the p-nitrophenyl phosphate and sulfate monoesters in aqueous solution has demonstrated that despite superficial similarities, the two reactions proceed through markedly different transition states with very different solvation effects, indicating that the requirements for the efficient catalysis of the two reactions by an enzyme will also be very different (and yet they are both catalyzed by thesame active site). This work explores the promiscuous phosphomonoesterase activity ofPAS. Specifically, we have investigated the identity of the most likely base for the initial activation of the unusual formylglycine hydrate nucleophile (which is common to many sulfatases), and demonstrate that a concerted substrate-as-base mechanism is fully consistent with the experimentally observed data. This is very similar to other related systems, and suggests that, as far as the phosphomonoesterase activity of PAS is concerned, the sulfatase behaves like a classical phosphatase, despite the fact that such a mechanism is unlikely to be available to the native substrate (based on pKa considerations and studies of model systems). Understanding such catalytic versatility can be used to design novel artificial enzymes that are far more proficient than the current generation ofdesigner enzymes. 

  • 46.
    Luo, Jinghui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    van Loo, Bert
    Kamerlin, Shina C. L.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Catalytic promiscuity in Pseudomonas aeruginosa arylsulfatase as an example of chemistry-driven protein evolution2012In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 586, no 11, p. 1622-1630Article in journal (Refereed)
    Abstract [en]

    In recent years, it has become increasingly clear that many enzymes are catalytically "promiscuous". This can provide a springboard for protein evolution, allowing enzymes to acquire novel functionality without compromising their native activities. We present here a detailed study of Pseudomonas aeruginosa arylsulfatase (PAS), which catalyzes the hydrolysis of a number of chemically distinct substrates, with proficiencies comparable to that towards its native reaction. We demonstrate that the main driving force for the promiscuity is the ability to exploit the electrostatic preorganization of the active site for the native substrate, providing an example of chemistry-driven protein evolution.

  • 47. Luo, Jinghui
    et al.
    Yu, Chien-Hung
    Yu, Huixin
    Borstnar, Rok
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Kamerlin, Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Graslund, Astrid
    Abrahams, Jan Pieter
    Warmlander, Sebastian K. T. S.
    Cellular Polyamines Promote Amyloid-Beta (A beta) Peptide Fibrillation and Modulate the Aggregation Pathways2013In: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 4, no 3, p. 454-462Article in journal (Refereed)
    Abstract [en]

    The cellular polyamines spermine, spermidine, and their metabolic precursor putrescine, have long been associated with cell-growth, tumor-related gene regulations, and Alzheimer's disease. Here, we show by in vitro spectroscopy and AFM imaging, that these molecules promote aggregation of amyloid-beta (A beta) peptides into fibrils and modulate the aggregation pathways. NMR measurements showed that the three polyamines share a similar binding mode to monomeric A beta(1-40) peptide. Kinetic ThT studies showed that already very low polyamine concentrations promote amyloid formation: addition of 10 mu M spermine (normal intracellular concentration is similar to 1 mM) significantly decreased the lag and transition times of the aggregation process. Spermidine and putrescine additions yielded similar but weaker effects. CD measurements demonstrated that the three polyamines induce different aggregation pathways, involving different forms of induced secondary structure. This is supported by AFM images showing that the three polyamines induce A beta(1-40) aggregates with different morphologies. The results reinforce the notion that designing suitable ligands which modulate the aggregation of A beta peptides toward minimally toxic pathways may be a possible therapeutic strategy for Alzheimer's disease.

  • 48. Luo, Jinghui
    et al.
    Yu, Chien-Hung
    Yu, Huixin
    Borstnar, Rok
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Graslund, Astrid
    Abrahams, Jan Pieter
    Warmlander, Sebastian K. T. S.
    Cellular Polyamines Promote Amyloid-Beta Peptide Fibrillation and Modulate the Aggregation Pathways2013In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 104, no 2, p. 389A-389AArticle in journal (Other academic)
  • 49.
    Ma, Huan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Szeler, Klaudia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Linking coupled motions and entropic effects to the catalytic activity of 2-deoxyribose-5-phosphate aldolase (DERA)2016In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 7, p. 1415-1421Article in journal (Refereed)
    Abstract [en]

    DERA, 2-deoxyribose-5-phosphate aldolase, catalyzes the retro-aldol cleavage of 2-deoxy-ribose-5-phosphate (dR5P) into glyceraldehyde-3-phosphate (G3P) and acetaldehyde in a branch of the pentose phosphate pathway. In addition to the physiological reaction, DERA also catalyzes the reverse addition reaction and, hence, is an interesting candidate for biocatalysis of carboligation reactions, which are central to synthetic chemistry. An obstacle to overcome for this enzyme to become a truly useful biocatalyst, however, is to relax the very strict dependency of this enzyme on phoshorylated substrates. We have studied herein the role of the non-canonical phosphate-binding site of this enzyme, consisting of Ser238 and Ser239, by site-directed and site-saturation mutagenesis, coupled to kinetic analysis of mutants. In addition, we have performed molecular dynamics simulations on the wild-type and four mutant enzymes, to analyse how mutations at this phosphate-binding site may affect the protein structure and dynamics. Further examination of the S239P mutant revealed that this variant increases the enthalpy change at the transition state, relative to the wild-type enzyme, but concomitant loss in entropy causes an overall relative loss in the TS free energy change. This entropy loss, as measured by the temperature dependence of catalysed rates, was mirrored in both a drastic loss in dynamics of the enzyme, which contributes to phosphate binding, as well as an overall loss in anti-correlated motions distributed over the entire protein. Our combined data suggests that the degree of anticorrelated motions within the DERA structure is coupled to catalytic efficiency in the DERA-catalyzed retro-aldol cleavage reaction, and can be manipulated for engineering purposes.

  • 50.
    Marsavelski, Aleksandra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Rudjer Boskovic Inst, Div Organ Chem & Biochem, Computat Organ Chem & Biochem Grp, Bijenicka Cesta 54, Zagreb 10000, Croatia;Univ Zagreb, Fac Sci, Dept Chem, Horvatovac 102a, Zagreb 10000, Croatia.
    Petrovic, Dusan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Bauer, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. KTH Royal Inst Technol, Dept Biophys, SciLifeLab, S-10691 Stockholm, Sweden.
    Vianello, Robert
    Rudjer Boskovic Inst, Div Organ Chem & Biochem, Computat Organ Chem & Biochem Grp, Bijenicka Cesta 54, Zagreb 10000, Croatia.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Empirical Valence Bond Simulations Suggest a Direct Hydride Transfer Mechanism for Human Diamine Oxidase2018In: ACS Omega, ISSN 2470-1343, Vol. 3, no 4, p. 3665-3674Article in journal (Refereed)
    Abstract [en]

    Diamine oxidase (DAO) is an enzyme involved in the regulation of cell proliferation and the immune response. This enzyme performs oxidative deamination in the catabolism of biogenic amines, including, among others, histamine, putrescine, spermidine, and spermine. The mechanistic details underlying the reductive half-reaction of the DAO-catalyzed oxidative deamination which leads to the reduced enzyme cofactor and the aldehyde product are, however, still under debate. The catalytic mechanism was proposed to involve a prototropic shift from the substrateSchiff base to the product-Schiff base, which includes the ratelimiting cleavage of the C alpha-H bond by the conserved catalytic aspartate. Our detailed mechanistic study, performed using a combined quantum chemical cluster approach with empirical valence bond simulations, suggests that the rate-limiting cleavage of the C alpha-H bond involves direct hydride transfer to the topaquinone cofactor. a mechanism that does not involve the formation of a Schiff base. Additional investigation of the D373E and D373N variants supported the hypothesis that the conserved catalytic aspartate is indeed essential for the reaction; however, it does not appear to serve as the catalytic base, as previously suggested. Rather, the electrostatic contributions of the most significant residues (including D373), together with the proximity of the Cu2+ cation to the reaction site, lower the activation barrier to drive the chemical reaction.

12 1 - 50 of 83
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf