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  • 251.
    Edin, Sofia
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Oruganti, Sreenivasa Rao
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Grundström, Christine
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Grundström, Thomas
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Interaction of calmodulin with Bcl10 modulates NF-kappaB activation.2010In: Molecular Immunology, ISSN 0161-5890, E-ISSN 1872-9142, Vol. 47, no 11-12, p. 2057-2064Article in journal (Refereed)
    Abstract [en]

    Calcium signals resulting from antigen receptor activation are important in determining the responses of a T or B lymphocyte to an antigen. Calmodulin (CaM), a multi-functional sensor of intracellular calcium (Ca(2+)) signals in cells, is required in the pathway from the T cell receptor (TCR) to activation of the key transcription factor NF-kappaB. Here we searched for a partner in direct interaction with CaM in the pathway, and found that CaM interacts specifically with the signaling adaptor Bcl10. The binding is Ca(2+) dependent and of high affinity, with a K(d) of approximately 160 nM. Proximity of CaM and Bcl10 in vivo is induced by increases in the intracellular Ca(2+) level. The interaction is localized to the CARD domain of Bcl10, which interacts with the CARD domain of the upstream signaling partner Carma1. Binding of CaM to Bcl10 is shown to inhibit the ability of Bcl10 to interact with Carma1, an interaction that is required for signaling from the TCR to NF-kappaB. Furthermore, a mutant of Bcl10 with reduced binding to CaM shows increased activation of an NF-kappaB reporter, which is further enhanced by activating stimuli. We propose a novel mechanism whereby the Ca(2+) sensor CaM regulates T cell responses to antigens by binding to Bcl10, thereby modulating its interaction with Carma1 and subsequent activation of NF-kappaB.

  • 252. Edqvist, Petra
    et al.
    Bröms, Jeanette E
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Steggo, Peter
    Forsberg, Åke
    Francis, Matthew
    Characterization of the tetratricopeptide repeats in type III secretion chaperones- mediators of substrate binding and specificityManuscript (Other academic)
  • 253.
    Edqvist, Petra J
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Multiple twists in the molecular tales of YopD and LcrH in type III secretion by Yersinia pseudotuberculosis2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The type III secretion system (T3SS) is a highly conserved secretion system among Gram negative bacteria that translocates anti-host proteins directly into the infected cells to overcome the host immune system and establish a bacterial infection. Yersinia pseudotuberculosis is one of three pathogenic Yersinia spp. that use a plasmid encoded T3SS to establish an infection. This complex multi-component Ysc-Yop system is tightly regulated in time and space. The T3SS is induced upon target cell contact and by growth in the absence of calcium. There are two kinds of substrates for the secretion apparatus, the translocator proteins that make up the pore in the eukaryotic target cell membrane, and the translocated effector proteins, that presumably pass through this pore en route to the eukaryotic cell interior.

    The essential YopD translocator protein is involved in several important steps during effector translocation, such as pore formation, effector translocation. Moreover, in complex with its cognate chaperone LcrH, it maintains regulatory control of yop gene expression. To understand the molecular mechanism of YopD function, we made sequential in-frame deletions throughout the entire protein and identified discrete functional domains that made it possible to separate the role of YopD in translocation from its role in pore formation and regulation, really supporting translocation to be a multi-step process. Further site-directed mutagenesis of the YopD C-terminus, a region important for these functions, revealed no function for amino acids in the coiled-coil domain, while hydrophobic residues within the alpha-helical amphipathic domain are functionally significant for regulation, pore formation and translocation of effectors.

    Unique to the T3SSs are the chaperones which are required for efficient type III protein secretion. The translocator-class chaperone LcrH binds two translocator proteins, YopB and YopD, which is necessary for their pre-secretory stabilization and their efficient secretion. We have shown that LcrH interacts with each translocator at a unique binding-site established by the folding of its three tandem tetratricopeptide repeats (TPRs). Beside the regulatory LcrH-YopD complex, LcrH complexes with YscY, a component of the Ysc-Yop T3SS, that is also essential for regulatory control. Interestingly the roles for LcrH do not end here, because it also appears to function in fine tuning the amount of effector translocation into target cells upon cell contact. Moreover, LcrH’s role in pre-secretory stability appears to be an in vitro phenomenon, since upon bacteria-host cell contact we found accumulated levels of YopB and YopD inside the bacteria in absence of a LcrH chaperone. This suggests the true function of LcrH is seen during target cell contact. In addition, these stable YopB and YopD are secreted in a Ysc-Yop independent manner in absence of a functional LcrH. We propose a role for LcrH in conferring substrate secretion pathway specificity, guiding its substrate to the cognate Ysc-Yop T3SS to secure subsequent effector translocation.

    Together, this work has sought to better understand the key functions of LcrH and YopD in Yersinia pathogenicity. Using an approach based heavily on recombinant DNA technology and tissue culture infections, the complex molecular cross-talk between chaperone and its substrate, and the effect this has on the Yersinia lifestyle, are now being discovered.

  • 254.
    Edqvist, Petra J
    et al.
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Aili, Margareta
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Liu, Junfa
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Francis, Matthew S
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Minimal YopB and YopD translocator secretion by Yersinia is sufficient for Yop-effector delivery into target cells.2007In: Microbes and infection, ISSN 1286-4579, E-ISSN 1769-714X, Vol. 9, no 2, p. 224-233Article in journal (Refereed)
    Abstract [en]

    Pathogenic Yersinia sp. utilise a common type III secretion system to translocate several anti-host Yop effectors into the cytosol of target eukaryotic cells. The secreted YopB and YopD translocator proteins are essential for this process, forming pores in biological membranes through which the effectors are thought to gain access to the cell interior. The non-secreted cognate chaperone, LcrH, also plays an important role by ensuring pre-secretory stabilisation and efficient secretion of YopB and YopD. This suggests that LcrH-regulated secretion of the translocators could be used by Yersinia to control effector translocation levels. We collected several LcrH mutants impaired in chaperone activity. These poorly bound, stabilised and/or secreted YopB and YopD in vitro. However, these mutants generally maintained stable substrates during a HeLa cell infection and these infected cells were intoxicated by translocated effectors. Surprisingly, this occurred in the absence of detectable YopB- and YopD-dependent pores in eukaryotic membranes. A functional type III translocon must therefore only require minuscule amounts of secreted translocator proteins. Based on these observations, LcrH dependent control of translocation via regulated YopB and YopD secretion would need to be exquisitely tight.

  • 255.
    Edqvist, Petra J
    et al.
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Bröms, Jeanette E
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Betts, Helen J
    Forsberg, Ake
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Pallen, Mark J
    Francis, Matthew S
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Tetratricopeptide repeats in the type III secretion chaperone, LcrH: their role in substrate binding and secretion.2006In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 59, no 1, p. 31-44Article in journal (Refereed)
    Abstract [en]

    Non-flagellar type III secretion systems (T3SSs) transport proteins across the bacterial cell and into eukaryotic cells. Targeting of proteins into host cells requires a dedicated translocation apparatus. Efficient secretion of the translocator proteins that make up this apparatus depends on molecular chaperones. Chaperones of the translocators (also called class-II chaperones) are characterized by the possession of three tandem tetratricopeptide repeats (TPRs). We wished to dissect the relations between chaperone structure and function and to validate a structural model using site-directed mutagenesis. Drawing on a number of experimental approaches and focusing on LcrH, a class-II chaperone from the Yersinia Ysc-Yop T3SS, we examined the contributions of different residues, residue classes and regions of the protein to chaperone stability, chaperone-substrate binding, substrate stability and secretion and regulation of Yop protein synthesis. We confirmed the expected role of the conserved canonical residues from the TPRs to chaperone stability and function. Eleven mutations specifically abrogated YopB binding or secretion while three mutations led to a specific loss of YopD secretion. These are the first mutations described for any class-II chaperone that allow interactions with one translocator to be dissociated from interactions with the other. Strikingly, all mutations affecting the interaction with YopB mapped to residues with side chains projecting from the inner, concave surface of the modelled TPR structure, defining a YopB interaction site. Conversely, all mutations preventing YopD secretion affect residues that lie on the outer, convex surface of the triple-TPR cluster in our model, suggesting that this region of the molecule represents a distinct interaction site for YopD. Intriguingly, one of the LcrH double mutants, Y40A/F44A, was able to maintain stable substrates inside bacteria, but unable to secrete them, suggesting that these two residues might influence delivery of substrates to the secretion apparatus.

  • 256.
    Edqvist, Petra J
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bröms, Jeanette E
    Åhlund, Monika K
    Forsberg, Åke
    Francis, Matthew S
    Functional insights into the YopD C-terminus through comprehensive site-directed mutagenesisManuscript (Other academic)
  • 257.
    Edqvist, Petra J
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Francis, Matthew S
    Examination of LcrH type III secretion chaperone function during Yersinia-eukaryotic cell contactManuscript (Other academic)
  • 258.
    Edqvist, Petra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Olsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Lavander, Moa
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Department of Microbiology, National Defense Research Agency, S-90182 Umeå.
    Sundberg, Lena
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Department of Microbiology, National Defense Research Agency, S-90182 Umeå.
    Forsberg, Åke
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Department of Microbiology, National Defense Research Agency, S-90182 Umeå.
    Wolf-Watz, Hans
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Lloyd, Scott
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    YscP and YscU Regulate Substrate Specificity of the Yersinia Type III Secretion System2003In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 185, no 7, p. 2259-2266Article in journal (Refereed)
    Abstract [en]

    Pathogenic Yersinia species use a type III secretion system to inhibit phagocytosis by eukaryotic cells. At 37 degrees C, the secretion system is assembled, forming a needle-like structure on the bacterial cell surface. Upon eukaryotic cell contact, six effector proteins, called Yops, are translocated into the eukaryotic cell cytosol. Here, we show that a yscP mutant exports an increased amount of the needle component YscF to the bacterial cell surface but is unable to efficiently secrete effector Yops. Mutations in the cytoplasmic domain of the inner membrane protein YscU suppress the yscP phenotype by reducing the level of YscF secretion and increasing the level of Yop secretion. These results suggest that YscP and YscU coordinately regulate the substrate specificity of the Yersinia type III secretion system. Furthermore, we show that YscP and YscU act upstream of the cell contact sensor YopN as well as the inner gatekeeper LcrG in the pathway of substrate export regulation. These results further strengthen the strong evolutionary link between flagellar biosynthesis and type III synthesis.

  • 259.
    Edwin, Aaron
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Persson, Cecilia
    Mayzel, Maxim
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Öhman, Anders
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Karlsson, B. Göran
    Sauer-Eriksson, A. Elisabeth
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Structure of the N-terminal domain of the metalloprotease PrtV from Vibrio cholerae2015In: Protein Science, ISSN 0961-8368, E-ISSN 1469-896X, Vol. 24, no 12, p. 2076-2080Article in journal (Refereed)
    Abstract [en]

    The metalloprotease PrtV from Vibrio cholerae serves an important function for the ability of bacteria to invade the mammalian host cell. The protein belongs to the family of M6 proteases, with a characteristic zinc ion in the catalytic active site. PrtV constitutes a 918 amino acids (102 kDa) multidomain pre-pro-protein that undergoes several N- and C-terminal modifications to form a catalytically active protease. We report here the NMR structure of the PrtV N- terminal domain (residues 23-103) that contains two short alpha-helices in a coiled coil motif. The helices are held together by a cluster of hydrophobic residues. Approximately 30 residues at the C-terminal end, which were predicted to form a third helical structure, are disordered. These residues are highly conserved within the genus Vibrio, which suggests that they might be functionally important.

  • 260.
    Edwin, Aaron
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Rompikuntal, Pramod
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stier, Gunter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Sauer-Eriksson, Elisabeth A.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Calcium binding by the PKD1 domain regulates interdomain flexibility in Vibrio cholerae metalloprotease PrtV2013In: FEBS Open Bio, E-ISSN 2211-5463, Vol. 3, p. 263-270Article in journal (Refereed)
    Abstract [en]

    Vibrio cholerae, the causative agent of cholera, releases several virulence factors including secreted proteases when it infects its host. These factors attack host cell proteins and break down tissue barriers and cellular matrix components such as collagen, laminin, fibronectin, keratin, elastin, and they induce necrotic tissue damage. The secreted protease PrtV constitutes one virulence factors of V. cholerae. It is a metalloprotease belonging to the M6 peptidase family. The protein is expressed as an inactive, multidomain, 102 kDa pre-pro-protein that undergoes several N- and C-terminal modifications after which it is secreted as an intermediate variant of 81 kDa. After secretion from the bacteria, additional proteolytic steps occur to produce the 55 kDa active M6 metalloprotease. The domain arrangement of PrtV is likely to play an important role in these maturation steps, which are known to be regulated by calcium. However, the molecular mechanism by which calcium controls proteolysis is unknown. In this study, we report the atomic resolution crystal structure of the PKD1 domain from V. cholera PrtV (residues 755–838) determined at 1.1 Å. The structure reveals a previously uncharacterized Ca2+-binding site located near linker regions between domains. Conformational changes in the Ca2+-free and Ca2+-bound forms suggest that Ca2+-binding at the PKD1 domain controls domain linker flexibility, and plays an important structural role, providing stability to the PrtV protein.

  • 261. Eggenschwiler, Reto
    et al.
    Moslem, Mohsen
    Fráguas, Mariane Serra
    Galla, Melanie
    Papp, Oliver
    Naujock, Maximilian
    Fonfara, Ines
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Max Planck Institute for Infection Biology, Department of Regulation in Infection Biology, Berlin, Germany.
    Gensch, Ingrid
    Wähner, Annabell
    Beh-Pajooh, Abbas
    Mussolino, Claudio
    Tauscher, Marcel
    Steinemann, Doris
    Wegner, Florian
    Petri, Susanne
    Schambach, Axel
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Cathomen, Toni
    Cantz, Tobias
    Improved bi-allelic modification of a transcriptionally silent locus in patient-derived iPSC by Cas9 nickase2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 38198Article in journal (Refereed)
    Abstract [en]

    Homology directed repair (HDR)-based genome editing via selectable long flanking arm donors can be hampered by local transgene silencing at transcriptionally silent loci. Here, we report efficient bi-allelic modification of a silent locus in patient-derived hiPSC by using Cas9 nickase and a silencing-resistant donor construct that contains an excisable selection/counter-selection cassette. To identify the most active single guide RNA (sgRNA)/nickase combinations, we employed a lentiviral vector-based reporter assay to determine the HDR efficiencies in cella. Next, we used the most efficient pair of sgRNAs for targeted integration of an improved, silencing-resistant plasmid donor harboring a piggyBac-flanked puro Delta tk cassette. Moreover, we took advantage of a dual-fluorescence selection strategy for bi-allelic targeting and achieved 100% counter-selection efficiency after bi-allelic excision of the selection/counter-selection cassette. Together, we present an improved system for efficient bi-allelic modification of transcriptionally silent loci in human pluripotent stem cells.

  • 262. Ekerfelt, C
    et al.
    Andersson, Marie
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Olausson, A
    Bergström, Sven
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Hultman, P
    Mercury exposure as a model for deviation of cytokine responses in expermental Lyme arthritis: HgCl2 treatment decreases T helper cell type 1-like responses and arthritis severity but delays eradication of Borrelia burgdorferi in C3H/HeN mice.2007In: Clinical and Experimental Immunology, Vol. 150, p. 189-197Article in journal (Refereed)
  • 263.
    Ekestubbe, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Bröms, Jeanette E.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Edgren, Tomas
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Fällman, Maria
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Francis, Matthew S.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Forsberg, Åke
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    The amino-terminal part of the needle-tip translocator LcrV of Yersinia pseudotuberculosis is required for early targeting of YopH and in vivo virulence2016In: Frontiers in Cellular and Infection Microbiology, E-ISSN 2235-2988, Vol. 6, article id 175Article in journal (Refereed)
    Abstract [en]

    Type III secretion systems (T3SS) are dedicated to targeting anti-host effector proteins into the cytosol of the host cell to promote bacterial infection. Delivery of the effectors requires three specific translocator proteins, of which the hydrophilic translocator, LcrV, is located at the tip of the T3SS needle and is believed to facilitate insertion of the two hydrophobic translocators into the host cell membrane. Here we used Yersinia as a model to study the role of LcrV in T3SS mediated intracellular effector targeting. Intriguingly, we identified N-terminal IcrV mutants that, similar to the wild-type protein, efficiently promoted expression, secretion and intracellular levels of Yop effectors, yet they were impaired in their ability to inhibit phagocytosis by J774 cells. In line with this, the YopH mediated dephosphorylation of Focal Adhesion Kinase early after infection was compromised when compared to the wild type strain. This suggests that the mutants are unable to promote efficient delivery of effectors to their molecular targets inside the host cell upon host cell contact. The significance of this was borne out by the fact that the mutants were highly attenuated for virulence in the systemic mouse infection model. Our study provides both novel and significant findings that establish a role for LcrV in early targeting of effectors in the host cell.

  • 264.
    Ekström, Jens-Ola
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Habayeb, Mazen S
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Srivastava, Vaibhav
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kieselbach, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wingsle, Gunnar
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hultmark, Dan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Drosophila Nora virus capsid proteins differ from those of other picorna-like viruses2011In: Virus Research, ISSN 0168-1702, E-ISSN 1872-7492, Vol. 160, no 1-2, p. 51-58Article in journal (Refereed)
    Abstract [en]

    The recently discovered Nora virus from Drosophila melanogaster is a single-stranded RNA virus. Its published genomic sequence encodes a typical picorna-like cassette of replicative enzymes, but no capsid proteins similar to those in other picorna-like viruses. We have now done additional sequencing at the termini of the viral genome, extending it by 455 nucleotides at the 5' end, but no more coding sequence was found. The completeness of the final 12,333-nucleotide sequence was verified by the production of infectious virus from the cloned genome. To identify the capsid proteins, we purified Nora virus particles and analyzed their proteins by mass spectrometry. Our results show that the capsid is built from three major proteins, VP4A, B and C, encoded in the fourth open reading frame of the viral genome. The viral particles also contain traces of a protein from the third open reading frame, VP3. VP4A and B are not closely related to other picorna-like virus capsid proteins in sequence, but may form similar jelly roll folds. VP4C differs from the others and is predicted to have an essentially α-helical conformation. In a related virus, identified from EST database sequences from Nasonia parasitoid wasps, VP4C is encoded in a separate open reading frame, separated from VP4A and B by a frame-shift. This opens a possibility that VP4C is produced in non-equimolar quantities. Altogether, our results suggest that the Nora virus capsid has a different protein organization compared to the order Picornavirales.

  • 265.
    Ekström, Jens-Ola
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). BioMediTech, FI-33014 University of Tampere, Finland.
    Hultmark, Dan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). BioMediTech, FI-33014 University of Tampere, Finland.
    A Novel Strategy for Live Detection of Viral Infection in Drosophila melanogaster2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 26250Article in journal (Refereed)
    Abstract [en]

    We have created a transgenic reporter for virus infection, and used it to study Nora virus infection in Drosophila melanogaster. The transgenic construct, Munin, expresses the yeast transcription factor Gal4, tethered to a transmembrane anchor via a linker that can be cleaved by a viral protease. In infected cells, liberated Gal4 will then transcribe any gene that is linked to a promoter with a UAS motif, the target for Gal4 transcription. For instance, infected cells will glow red in the offspring of a cross between the Munin stock and flies with a UAS-RFPnls transgene (expressing a red fluorescent protein). In such flies we show that after natural infection, via the faecal-oral route, 5-15% of the midgut cells are infected, but there is little if any infection elsewhere. By contrast, we can detect infection in many other tissues after injection of virus into the body cavity. The same principle could be applied for other viruses and it could also be used to express or suppress any gene of interest in infected cells.

  • 266.
    El Wakil, Abeer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). CNRS, Inst Pharmacol Mol & Cellulaire, 660 Route Lucioles, F-06560 Valbonne, France.
    Mari, B.
    Barhanin, J.
    Lalli, E.
    Genomic Analysis of Sexual Dimorphism of Gene Expression in the Mouse Adrenal Gland2013In: Hormone and Metabolic Research, ISSN 0018-5043, E-ISSN 1439-4286, Vol. 45, no 12, p. 870-873Article in journal (Refereed)
    Abstract [en]

    A relevant gender difference exists in adrenal physiology and propensity to disease. In mice, a remarkable sexual dimorphism is present in several components of the hypothalamic-pituitary-adrenal axis, with females displaying higher adrenal weight, plasma ACTH, corticosterone, and aldosterone levels than males. The molecular bases of this sexual dimorphism are little known. We have compared global gene expression profiles in males vs. female mouse adrenal glands and also studied the effect that testosterone treatment and castration have on adrenal gene expression in female vs. male mice, respectively. Our study evidenced a set of 71 genes that are coordinately modulated according to sex and hormonal treatments and represent the core sexually dimorphic expression program in the mouse adrenal gland. Moreover, we show that some genes involved in steroid metabolism have a remarkable sexual dimorphic expression and identify new potential markers for the adrenal X-zone, a transitory cellular layer in the inner adrenal cortex, which spontaneously regresses at puberty in males and during the first pregnancy in females and has an uncertain physiological role. Finally, sexually dimorphic expression of the transcriptional regulators Nr5a1 and Nr0b1 may explain at least in part the differences in adrenal steroidogenesis between sexes.

  • 267. Elbir, Haitham
    et al.
    Gimenez, Gregory
    Robert, Catherine
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Cutler, Sally
    Raoult, Didier
    Drancourt, Michel
    Complete genome sequence of Borrelia crocidurae2012In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 194, no 14, p. 3723-3724Article in journal (Refereed)
    Abstract [en]

    We announce the draft genome sequence of Borrelia crocidurae (strain Achema). The 1,557,560-bp genome (27% GC content) comprises one 919,477-bp linear chromosome and 638,083-bp plasmids that together carry 1,472 open reading frames, 32 tRNAs, and three complete rRNAs, with almost complete colinearity between B. crocidurae and Borrelia duttonii chromosomes.

  • 268.
    Elbir, Haitham
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Larsson, Pär
    Division of CBRN Security and Defence, FOI Swedish Defence Research Agency, Umeå, Sweden.
    Normark, Johan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Upreti, Mukunda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Korenberg, Edward
    Gamaleya Research Institute for Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow, Russian Federation.
    Larsson, Christer
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Genome Sequence of the Asiatic Species Borrelia persica2014In: Genome Announcements, ISSN 2169-8287, E-ISSN 2169-8287, Vol. 2, no 1, article id e01127-13Article in journal (Refereed)
    Abstract [en]

    We report the complete genome sequence of Borrelia persica, the causative agent of tick-borne relapsing fever borreliosis on the Asian continent. Its genome of 1,784,979 bp contains 1,850 open reading frames, three ribosomal RNAs, and 32 tRNAs. One clustered regularly interspaced short palindromic repeat (CRISPR) was detected.

  • 269.
    Elbir, Haitham
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Sitlani, Parth
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Departments of Microbiology and Molecular Genetics and Medicine, University of California Irvine, Irvine, California, USA.
    Barbour, Alan G.
    Chromosome and Megaplasmid Sequences of Borrelia anserina (Sakharoff 1891), the Agent of Avian Spirochetosis and Type Species of the Genus2017In: Genome Announcements, ISSN 2169-8287, E-ISSN 2169-8287, Vol. 5, no 11, article id e00018-17Article in journal (Refereed)
    Abstract [en]

    Sequences of the linear chromosome and plasmids of Borrelia anserina, the cause of avian spirochetosis of poultry, revealed a smaller genome than those of other Borrelia spp. transmitted by argasid ticks. Missing or disrupted genes included a dam methylase and those in the pathway for synthesis of phospholipids from glycerol.

  • 270. Elfving, Karin
    et al.
    Olsen, Björn
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Waldenström, Jonas
    Lundkvist, Åke
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Mejlon, Hans
    Nilsson, Kenneth
    Dissemination of spotted fever rickettsia agents in Europe by migrating birds2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 1, p. e8572-Article in journal (Refereed)
    Abstract [en]

    Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp.IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases.

  • 271.
    Elluri, Sridhar
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India.
    Enow Oben Ayuk, Constance
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Vdovikova, Svitlana
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Rompikuntal, Pramod K
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Dongre, Mitesh
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Carlsson, Sven
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Pal, Amit
    Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Kolkata, West Bengal, India.
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Outer membrane vesicles mediate transport of biologically active Vibrio cholerae cytolysin (VCC) from V. cholerae strains2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 9, article id e106731Article in journal (Refereed)
    Abstract [en]

    Background Outer membrane vesicles (OMVs) released from Gram-negative bacteria can serve as vehicles for the translocation of virulence factors. Vibrio cholerae produce OMVs but their putative role in translocation of effectors involved in pathogenesis has not been well elucidated. The V. cholerae cytolysin (VCC), is a pore-forming toxin that lyses target eukaryotic cells by forming transmembrane oligomeric β-barrel channels. It is considered a potent toxin that contributes to V. cholerae pathogenesis. The mechanisms involved in the secretion and delivery of the VCC have not been extensively studied.

    Methodology/Principal Findings OMVs from V. cholerae strains were isolated and purified using a differential centrifugation procedure and Optiprep centrifugation. The ultrastructure and the contents of OMVs were examined under the electron microscope and by immunoblot analyses respectively. We demonstrated that VCC from V. cholerae strain V:5/04 was secreted in association with OMVs and the release of VCC via OMVs is a common feature among V. cholerae strains. The biological activity of OMV-associated VCC was investigated using contact hemolytic assay and epithelial cell cytotoxicity test. It showed toxic activity on both red blood cells and epithelial cells. Our results indicate that the OMVs architecture might play a role in stability of VCC and thereby can enhance its biological activities in comparison with the free secreted VCC. Furthermore, we tested the role of OMV-associated VCC in host cell autophagy signalling using confocal microscopy and immunoblot analysis. We observed that OMV-associated VCC triggered an autophagy response in the target cell and our findings demonstrated for the first time that autophagy may operate as a cellular defence mechanism against an OMV-associated bacterial virulence factor.

    Conclusion/Significance Biological assays of OMVs from the V. cholerae strain V:5/04 demonstrated that OMV-associated VCC is indeed biologically active and induces toxicity on mammalian cells and furthermore can induce autophagy.

  • 272. Elsholz, Alexander K. W.
    et al.
    Birk, Marlene S.
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Department of Regulation in Infection Biology, Max Planck Institute for Infection Biology, Berlin, Germany; Humboldt University, Berlin, Germany.
    Turgay, Kuersad
    Functional Diversity of AAA plus Protease Complexes in Bacillus subtilis2017In: Frontiers in Molecular Biosciences, ISSN 2296-889X, Vol. 4, article id 44Article, review/survey (Refereed)
    Abstract [en]

    Here, we review the diverse roles and functions of AAA+ protease complexes in protein homeostasis, control of stress response and cellular development pathways by regulatory and general proteolysis in the Gram-positive model organism Bacillus subtilis. We discuss in detail the intricate involvement of AAA+ protein complexes in controlling sporulation, the heat shock response and the role of adaptor proteins in these processes. The investigation of these protein complexes and their adaptor proteins has revealed their relevance for Gram-positive pathogens and their potential as targets for new antibiotics.

  • 273.
    Eneqvist, Therese
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Andersson, Karin
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Olofsson, Anders
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Lundgren, Erik
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    The beta-slip: a novel concept in transthyretin amyloidosis.2000In: Mol Cell, ISSN 1097-2765, Vol. 6, no 5, p. 1207-18Article in journal (Refereed)
    Abstract [en]

    Transthyretin is a tetrameric plasma protein associated with two forms of amyloid disease. The structure of the highly amyloidogenic transthyretin triple mutant TTRG53S/E54D/L55S determined at 2.3 A resolution reveals a novel conformation: the beta-slip. A three-residue shift in beta strand D places Leu-58 at the position normally occupied by Leu-55 now mutated to serine. The beta-slip is best defined in two of the four monomers, where it makes new protein-protein interactions to an area normally involved in complex formation with retinol-binding protein. This interaction creates unique packing arrangements, where two protein helices combine to form a double helix in agreement with fiber diffraction and electron microscopy data. Based on these findings, a novel model for transthyretin amyloid formation is presented.

  • 274.
    Eneqvist, Therese
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Olofsson, Anders
    Faculty of Medicine, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Medicine).
    Ando, Yukio
    Miyakawa, Taihei
    Katsuragi, Shoichi
    Jass, Jana
    Molecular Biology (Faculty of Medicine).
    Lundgren, Erik
    Molecular Biology (Faculty of Medicine).
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Disulfide-bond formation in the transthyretin mutant Y114C prevents amyloid fibril formation in vivo and in vitro.2002In: Biochemistry, ISSN 0006-2960, Vol. 41, no 44, p. 13143-51Article in journal (Refereed)
    Abstract [en]

    The Y114C mutation in human transthyretin (TTR) is associated with a particular form of familial amyloidotic polyneuropathy. We show that vitreous aggregates ex vivo consist of either regular amyloid fibrils or disordered disulfide-linked precipitates that maintain the ability to bind Congo red. Furthermore, we demonstrate in vitro that the ATTR Y114C mutant exists in three forms: one unstable but nativelike tetrameric form, one highly aggregated form in which a network of disulfide bonds is formed, and one fibrillar form. The disulfide-linked aggregates and the fibrillar form of the mutant can be induced by heat induction under nonreduced and reduced conditions, respectively. Both forms are recognized by the amyloid specific antibody MAB(39-44). In a previous study, we have linked exposure of this epitope in TTR to a three-residue shift in beta-strand D. The X-ray crystallographic structure of reduced tetrameric ATTR Y114C shows a structure similar to that of the wild type but with a more buried position of Cys10 and with beta-mercaptoethanol associated with Cys114, verifying the strong tendency for this residue to form disulfide bonds. Combined with the ex vivo data, our in vitro findings suggest that ATTR Y114C can lead to disease either by forming regular unbranched amyloid fibrils or by forming disulfide-linked aggregates that maintain amyloid-like properties but are unable to form regular amyloid fibrils.

  • 275.
    Engström, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Bailey, Leslie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Önskog, Thomas
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    A comparative study of RNA and DNA as internal gene expression controls early in the developmental cycle of Chlamydia pneumoniae2010In: FEMS Immunology and Medical Microbiology, ISSN 0928-8244, E-ISSN 1574-695X, Vol. 58, no 2, p. 244-253Article in journal (Refereed)
    Abstract [en]

    Many microbial pathogens invade and proliferate within host cells and the molecular mechanism underlying this behavior is currently being revealed for several bacterial species. Testing clinically relevant antibacterial compounds and elucidating their effects on gene expression requires adequate controls, especially when studying genetically intractable organisms such as Chlamydia spp., for which various gene fusions cannot be constructed. Until now, relative mRNA levels in Chlamydia have been measured using different internal gene expression controls, including 16S rRNA, mRNAs, and DNA. Here, we compared the advantages and disadvantages of various internal expression controls during the early phase of Chlamydia pneumoniae development. The relative abundance of target mRNAs varied using the different internal control RNAs. This was partly due to variation in the transcript stability of the RNA species. Also, seven out of nine of the analyzed RNAs increased fivefold or more between 2 and 14 h postinfection, while the amount of DNA and number of cells remained essentially unaltered. Our results suggest that RNA should not be used as a gene expression control during the early phase of Chlamydia development, and that intrinsic bacterial DNA is preferable for that purpose because it is stable, abundant, and its relative amount is generally correlated with bacterial numbers.

  • 276.
    Engström, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Bergström, Malin
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Alfaro, Astrid C.
    Krishnan, K. Syam
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bahnan, Wael
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Almqvist, Fredrik
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Expansion of the Chlamydia trachomatis inclusion does not require bacterial replication2015In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 305, no 3, p. 378-382Article in journal (Refereed)
    Abstract [en]

    Chlamydia trachomatis replication takes place inside of a host cell, exclusively within a vacuole known as the inclusion. During an infection, the inclusion expands to accommodate the increasing numbers of C. trachomatis. However, whether inclusion expansion requires bacterial replication and/or de novo protein synthesis has not been previously investigated in detail. Therefore, using a chemical biology approach, we herein investigated C. trachomatis inclusion expansion under varying conditions in vitro. Under normal cell culture conditions, inclusion expansion correlated with C trachomatis replication. When bacterial replication was inhibited using KSK120: an inhibitor that targets C. trachomatis glucose metabolism, inclusions expanded even in the absence of bacterial replication. In contrast, when bacterial protein synthesis was inhibited using chloramphenicol, expansion of inclusions was blocked. Together, these data suggest that de novo protein synthesis is necessary, whereas bacterial replication is dispensable for C trachomatis inclusion expansion. (C) 2015 The Authors. Published by Elsevier GmbH.

  • 277.
    Engström, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Krishnan, K. Syam
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ngyuen, Bidong D.
    Chorell, Erik
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Normark, Johan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Silver, Jim
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bastidas, Robert J.
    Welch, Matthew D.
    Hultgren, Scott J.
    Wolf-Watz, Hans
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Valdivia, Raphael H.
    Almqvist, Fredrik
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    A 2-Pyridone-Amide Inhibitor Targets the Glucose Metabolism Pathway of Chlamydia trachomatis2015In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 6, no 1, article id e02304-14Article in journal (Refereed)
    Abstract [en]

    In a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection. IMPORTANCE Chlamydia trachomatis is a bacterial pathogen of humans that causes a common sexually transmitted disease as well as eye infections. It grows only inside cells of its host organism, within a parasitophorous vacuole termed the inclusion. Little is known, however, about what bacterial components and processes are important for C. trachomatis cellular infectivity. Here, by using a visual screen for compounds that affect bacterial distribution within the chlamydial inclusion, we identified the inhibitor KSK120. As hypothesized, the altered bacterial distribution induced by KSK120 correlated with a block in C. trachomatis infectivity. Our data suggest that the compound targets the glucose-6-phosphate (G-6P) metabolism pathway of C. trachomatis, supporting previous indications that G-6P metabolism is critical for C. trachomatis infectivity. Thus, KSK120 may be a useful tool to study chlamydial glucose metabolism and has the potential to be used in the treatment of C. trachomatis infections.

  • 278.
    Engström, Patrik
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nguyen, Bidong D.
    Normark, Johan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Nilsson, Ingela
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Bastidas, Robert J.
    Gylfe, Åsa
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Elofsson, Mikael
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fields, Kenneth A.
    Valdivia, Raphael H.
    Wolf-Watz, Hans
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Mutations in hemG Mediate Resistance to Salicylidene Acylhydrazides, Demonstrating a Novel Link between Protoporphyrinogen Oxidase (HemG) and Chlamydia trachomatis Infectivity2013In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 195, no 18, p. 4221-4230Article in journal (Refereed)
    Abstract [en]

    Salicylidene acylhydrazides (SAHs) inhibit the type III secretion system (T3S) of Yersinia and other Gram-negative bacteria. In addition, SAHs restrict the growth and development of Chlamydia species. However, since the inhibition of Chlamydia growth by SAH is suppressed by the addition of excess iron and since SAHs have an iron-chelating capacity, their role as specific T3S inhibitors is unclear. We investigated here whether SAHs exhibit a function on C. trachomatis that goes beyond iron chelation. We found that the iron-saturated SAH INP0341 (IS-INP0341) specifically affects C. trachomatis infectivity with reduced generation of infectious elementary body (EB) progeny. Selection and isolation of spontaneous SAH-resistant mutant strains revealed that mutations in hemG suppressed the reduced infectivity caused by IS-INP0341 treatment. Structural modeling of C. trachomatis HemG predicts that the acquired mutations are located in the active site of the enzyme, suggesting that IS-INP0341 inhibits this domain of HemG and that protoporphyrinogen oxidase (HemG) and heme metabolism are important for C. trachomatis infectivity.

  • 279.
    Enow, Constance
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Studies of pore-forming bacterial protein toxins in Escherichia coli2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Escherichia coli, a Gram-negative bacterium, which can be classified into three groups: the commensal, intestinal pathogenic (IPEC) and extra-intestinal pathogenic (ExPEC) E. coli. The cytolysin A (ClyA) protein, a 34-kDa pore-forming toxin, encoded by a gene found in both non-pathogenic and pathogenic E. coli and in Salmonella enterica serovars Typhi and Paratyphi. It mediates a cytotoxic effect on various mammalian cells. ClyA is released by E. coli via outer membrane vesicles (OMVs) after reaching the periplasm via an unknown mechanism through the inner membrane. The gene is silenced by mutations in some of the most studied ExPEC strains suggesting that the locus would be subject to patho-adaptive alterations.

    To study if the mutations of the clyA gene in E. coli strains was particular to certain strains, the sequences of the clyA gene locus of a set of ExPEC isolates and of the E. coli collection of reference strains (ECOR) were compared. The ExPEC strains – uropathogenic and neonatal meningitis E. coli (UPEC and NMEC) strains contained various ΔclyA alleles. Next, a functional clyA gene locus was restored and tagged with luxAB in the chromosome of the UPEC strain 536. Luciferase activity of the bacteria carrying the restored gene showed that the clyA gene expression is highly increased at the late logarithmic growth phase when compared to the non-pathogenic E. coli K-12 strain. A higher transcriptional level of the clyA+ gene was observed when the SfaX regulatory protein was heterologously overproduced. It was concluded that the clyA+ gene is expressed at elevated levels in the UPEC strain and this is at least in part due to the SfaX/PapX transcriptional regulators.

    Studies of clyA::phoA fusions obtained by transposon TnphoA insertion mutagenesis showed that the first 12 amino acid residues of ClyA was sufficient for translocation of the protein chimera into the periplasm and to the OMVs. The role of the two cysteine residues in ClyA for protein translocation was tested by introducing substitution mutations. The results indicated that the C-terminal Cys (ClyAC 285S) is important for localization and/or stability of the protein in the periplasm. Structural analysis of ClyAwt purified from the periplasm revealed that the protein forms dimeric complexes. Upon treatment with the reducing agent DTT the ClyA protein readily assembled into typical pore complexes as revealed by electron miscroscopic analysis. In conclusion, the ClyA protein is present in the periplasm in a conformation that prevents it from forming pores in the bacterial membranes.

    Vibrio cholerae cytolysin (VCC) is a pore-forming toxin which induces lysis of mammalian cells by forming transmembrane channels. Although the biophysical activities of VCC were well studied, there was no detailed analysis of VCC secretion. Our study demonstrated that a fraction of the VCC was secreted in association with OMVs. OMV-associated VCC from the wild type V. cholerae strain V:5/04 is biologically active as shown by toxic effects on mammalian cells, interestingly, OMV-associated VCC was more active than purified VCC. Both environmental and clinical V. cholerae isolates transport VCC via OMVs. In addition, when the vcc gene is heterologously expressed in E. coli, OMV-associated secretion of VCC was also observed. We suggest that OMV-mediated release of VCC is a feature shared with ClyA.

  • 280.
    Enow, Constance
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Mizunoe, Yoshimitsu
    Huang, Shengua
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meier, Elke
    Benz, Roland
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Localization and structure of the ClyA protein in Escherichia coli before secretion and pore-formationManuscript (preprint) (Other academic)
  • 281.
    Enow Oben Ayuk, Constance
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Zlatkov, Nikola
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Westermark, Marie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Duperthuy, Marylise
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Elevated recombinant clyA gene expression in the uropathogenic Escherichia coli strain 536, a clue to explain pathoadaptive mutations in a subset of extraintestinal E. coli strains2014In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 14, p. 216-Article in journal (Refereed)
    Abstract [en]

    There are at least four different variants of ΔclyA, suggesting that such deletions in clyA have arisen at more than one occasion. On the basis of this occurrence of the truncated clyA genes, we considered that there may be a patho-adaptive selection for deletions in clyA in extraintestinal pathogenic E. coli. In E. coli K-12 the clyA gene has been viewed as “cryptic” since it is tightly silenced by the nucleoid structuring protein H-NS. We constructed a restored clyA+ locus in derivatives of the UPEC strain 536 for further investigation of this hypothesis and, in particular, how the gene would be expressed. Our results show that the level of clyA+ expression is highly increased in the UPEC derivatives in comparison with the non-pathogenic E. coli K-12. Transcription of the clyA+ gene was induced to even higher levels when the SfaX regulatory protein was overproduced. The derivative with a restored clyA+ locus displayed a somewhat slower growth than the parental UPEC strain 536 when a sub-inhibitory concentration of the antimicrobial peptide Polymyxin B was added to the growth medium.

  • 282.
    Ericzon, Bo-Göran
    et al.
    Head Division of Transplantation Surgery, CLINTEC, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
    Lundgren, Erik
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Suhr, Ole B.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Liver Transplantation for Transthyretin Amyloidosis2009In: Recent Advances in Transthyretin Evolution, Structure and Biological Functions / [ed] Dr. Samantha J. Richardson, Dr. Vivian Cody, New York: Springer Berlin/Heidelberg, 2009, p. 239-260Chapter in book (Other academic)
    Abstract [en]

    Liver transplantation has until now proved to be the only treatment available that halts the progression of hereditary transthyretin (TTR) associated amyloidosis. The rationale behind the procedure is to replace the liver producing variant TTR with one that produces wild type TTR only, and thereby cease the production of amyloidogenic TTR (ATTR). Even though the transplantation does not improve the patient's symptoms, the progression of the disease comes to a halt for a majority of patients. However, unforeseen complications after the transplantation have emerged, in particular a continuous amyloid formation in the heart observed in non-ATTR Val30Met mutations. Thus, combined liver and heart transplantation has been performed in selected cases. Since the ATTR liver functions normally apart from a synthesis of the variant TTR, utilisation of ATTR-amyloid patients' livers for transplantation of liver disease patients has been performed. In a few patients, development of amyloid disease has been reported, but the procedure remains an important source of organs, especially for patients with hepatocellular cancer.

  • 283.
    Eriksson, David
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Immunology/Immunchemistry.
    Blomberg, Jeanette
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Lindgren, Theres
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Immunology/Immunchemistry.
    Löfroth, Per-Olov
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Stigbrand, Torgny
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Immunology/Immunchemistry.
    Iodine-131 induces mitotic catastrophes and activates apoptotic pathways in HeLa Hep2 cells2008In: Cancer Biotherapy and Radiopharmaceuticals, ISSN 1084-9785, E-ISSN 1557-8852, Vol. 23, no 5, p. 541-549Article in journal (Refereed)
    Abstract [en]

    Iodine-131 (131I) has been used both in unconjugated form and conjugated to antibody derivates (i.e., radioimmunotherapy; RIT) to treat malignant diseases. The mechanisms by which 131I-irradiation causes growth retardation are, however, inadequately understood. The aim of this study was to elucidate the sequential molecular and cellular events that initiate cell death in HeLa Hep2 cells exposed to 131I. In this paper, HeLa Hep2 cells were found to display a transient G2-M arrest following irradiation, but then reentered the cell cycle still containing unrepaired cellular damage. An increase of multipolar mitotic spindles, as well as a significant increase in centrosome numbers from 8.8% +/- 1.9% in controls to 54.7% +/- 2.2% in irradiated cells, was observed (p < 0.0001). A subsequent failure of cytokinesis caused the cells to progress into mitotic catastrophe. This was accompanied by the formation of giant cells with multiple nuclei, multilobulated nuclei, and an increased frequency of polyploidy cells. A fraction of the cells also displayed apoptotic features, including the activation of initiator caspases-2, -8, -9, and effector caspase-3, as well as cleavage of poly(ADP-ribose) polymerase, a cell-death substrate for active caspase-3. These findings demonstrate that mitotic catastrophes and the activation of a delayed type of apoptosis might be important mechanisms involved in cell death following the RIT of solid tumors with -emitting radionuclides, such as 131I.

  • 284.
    Eriksson, Therese
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Exploiting Drosophila as a model system for studying anaplastic lymphoma kinase in vivo2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anaplastic Lymphoma Kinase (ALK) is a Receptor Tyrosine Kinase (RTK) and an oncogene associated with several human diseases, but its normal function in humans and other vertebrates is unclear. Drosophila melanogaster has an ALK homolog, demonstrating that the RTK has been conserved throughout evolution. This makes Drosophila a suitable model organism for studying not only Drosophila ALK function, but also to study mammalian forms of ALK. In Drosophila the ligand Jeb activates ALK, initiating signaling crucial for visceral mesoderm development. The activating ligand for mammalian ALK is unclear, and for this reason Drosophila was employed in a cross-species approach to investigate whether Drosophila Jeb can activate mouse ALK. Jeb is unable to activate mouse ALK, and therefore mouse ALK is unable to substitute for and rescue the Drosophila ALK mutant phenotype. This suggests that there has been significant evolution in the ALK-ligand relationship between the mouse and Drosophila.

    In humans ALK has recently been shown to be involved in the development of neuroblastoma, a cancer tumor in children. I have developed a Drosophila model for examining human gain of function ALK mutants found in neuroblastoma patients. The various ALK variants have acquired point mutations in the kinase domain that have been predicted to activate the RTK in a constitutive and ligand independent manner. When expressed in the fly eye, active human ALK mutants result in a rough eye phenotype, while inactive wild type ALK does not, due to the lack of an activating ligand in the fly. In this way  several of the ALK mutations identified in neuroblastoma patients could be confirmed to be activated in a ligand independent manner. Moreover, a novel ALK mutant; ALKF1174S, was discovered in a neuroblastoma patient and was in the Drosophila model shown to be a gain of function mutation, and a previously predicted gain of function mutation; ALKI1250T, was shown to be a kinase dead mutation. This fly model can also be used for testing ALK selective inhibitors, for identifying activating ligands for human ALK and for identifying conserved components of the ALK signaling pathway.

    Gut musculature development in Drosophila is dependent on ALK signaling, while somatic muscle development is not. Proteins of the Wasp-Scar signaling network regulate Arp2/3-complex mediated actin polymerization, and I have investigated their function in visceral and somatic muscle fusion. I found that Verprolin and other members of this protein family are essential for somatic but not visceral muscle development. Despite fusion defects in both tissues in Verprolin and other examined mutants, gut development proceeds, suggesting that fusion is not crucial for visceral mesoderm development. Hence the actin polymerization machinery functions in both somatic and visceral muscle fusion, but this process only appears to be essential in somatic muscle development.

  • 285.
    Eriksson, Therese
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Varshney, Gaurav
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Aspenström, Pontus
    Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute, Stockholm, Sweden.
    Palmer, Ruth
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Characterization of the role of Vrp1 in cell fusion during the development of visceral muscle of Drosophila melanogaster2010In: BMC Developmental Biology, ISSN 1471-213X, E-ISSN 1471-213X, Vol. 10, no 86Article in journal (Refereed)
    Abstract [en]

    Background: In Drosophila muscle cell fusion takes place both during the formation of the somatic mesodermand the visceral mesoderm, giving rise to the skeletal muscles and the gut musculature respectively. The coreprocess of myoblast fusion is believed to be similar for both organs. The actin cytoskeleton regulator Verprolin actsby binding to WASP, which in turn binds to the Arp2/3 complex and thus activates actin polymerization. WhileVerprolin has been shown to be important for somatic muscle cell fusion, the function of this protein in visceralmuscle fusion has not been determined.Results: Verprolin is specifically expressed in the fusion competent myoblasts of the visceral mesoderm, suggestinga role in visceral mesoderm fusion. We here describe a novel Verprolin mutant allele which displays subtle visceralmesoderm fusion defects in the form of mislocalization of the immunoglobulin superfamily molecule Duf/Kirre,which is required on the myoblast cell surface to facilitate attachment between cells that are about to fuse,indicating a function for Verprolin in visceral mesoderm fusion. We further show that Verprolin mutant cells arecapable of both migrating and fusing and that the WASP-binding domain of Verprolin is required for rescue of theVerprolin mutant phenotype.Conclusions: Verprolin is expressed in the visceral mesoderm and plays a role in visceral muscle fusion as shownby mislocalization of Duf/Kirre in the Verprolin mutant, however it is not absolutely required for myoblast fusion ineither the visceral or the somatic mesoderm.

  • 286.
    Ermert, David
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Urban, Constantin F
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Laube, Britta
    Goosmann, Christian
    Zychlinsky, Arturo
    Brinkmann, Volker
    Mouse neutrophil extracellular traps in microbial infections.2009In: Journal of innate immunity, ISSN 1662-8128, Vol. 1, no 3, p. 181-193Article in journal (Refereed)
    Abstract [en]

    Neutrophil extracellular traps (NETs) play an important role in innate immunity to microbial infections. NETs have been described in several species, but the molecular details of NET formation and their role in infection has not been addressed, partly because we lack optimal experimental models. Here we describe tools to investigate NET formation in neutrophils isolated from mice. Upon in vitro stimulation of wild-type mouse neutrophils with PMA, we analyzed 3 important steps in the process of NET formation: reactive oxygen species (ROS) production, NET cell death and NET release. As expected, neutrophils from NADPH oxidase-deficient mice failed to produce ROS and did not die nor release NETs upon stimulation. We found that neutrophils from several mouse strains produced NETs with different efficiency and that NET formation correlated with the amount of ROS produced. Activation with Candida albicans also resulted in ROS production and NET cell death. The hyphal form of this fungus induced NETs more effectively than the yeast form. With this work, we provide tools to study in vitro NET assembly in the mouse system.

  • 287.
    Erttmann, Saskia F.
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gekara, Nelson O.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Fällman, Maria
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bacteria Induce Prolonged PMN Survival via a Phosphatidylcholine-Specific Phospholipase C- and Protein Kinase C-Dependent Mechanism2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 1, p. e87859-Article in journal (Refereed)
    Abstract [en]

    Polymorphonuclear leukocytes (PMNs) are essential for the human innate immune defense, limiting expansion of invading microorganisms. PMN turnover is controlled by apoptosis, but the regulating signaling pathways remain elusive, largely due to inherent differences between mice and humans that undermine use of mouse models for understanding human PMN biology. Here, we aim to elucidate signal transduction mediating survival of human peripheral blood PMNs in response to bacteria, such as Yersinia pseudotuberculosis, an enteropathogen that causes the gastro-intestinal disease yersiniosis, as well as Escherichia coli and Staphylococcus aureus. Determinations of cell death reveal that uninfected control cells undergo apoptosis, while PMNs infected with either Gram-positive or -negative bacteria show profoundly increased survival. Infected cells exhibit decreased caspase 3 and 8 activities, increased mitochondrial integrity and are resistant to apoptosis induced by a death receptor ligand. This bacteria-induced response is accompanied by pro-inflammatory cytokine production including interleukin-8 and tumor necrosis factor-a competent to attract additional PMNs. Using agonists and pharmacological inhibitors, we show participation of Toll-like receptor 2 and 4, and interestingly, that protein kinase C (PKC) and phosphatidylcholine-specific phospholipase C (PC-PLC), but not tyrosine kinases or phosphatidylinositol-specific phospholipase C (PI-PLC) are key players in this dual PMN response. Our findings indicate the importance of prolonged PMN survival in response to bacteria, where general signaling pathways ensure complete exploitation of PMN anti-microbial capacity.

  • 288.
    Erttmann, Saskia F.
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Härtlova, Anetta
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Sloniecka, Marta
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Raffi, Faizal A. M.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Hosseinzadeh, Ava
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Edgren, Tomas
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Rofougaran, Reza
    Resch, Ulrike
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Fällman, Maria
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Ek, Torben
    Gekara, Nelson O.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Loss of the DNA Damage Repair Kinase ATM Impairs Inflammasome-Dependent Anti-Bacterial Innate Immunity2016In: Immunity, ISSN 1074-7613, E-ISSN 1097-4180, Vol. 45, no 1, p. 106-118Article in journal (Refereed)
    Abstract [en]

    The ATM kinase is a central component of the DNA damage repair machinery and redox balance. ATM dysfunction results in the multisystem disease ataxia-telangiectasia (AT). A major cause of mortality in AT is respiratory bacterial infections. Whether ATM deficiency causes innate immune defects that might contribute to bacterial infections is not known. Here we have shown that loss of ATM impairs inflammasome- dependent anti-bacterial innate immunity. Cells from AT patients or Atm(-/-) mice exhibited diminished interleukin-1 beta (IL-1 beta) production in response to bacteria. In vivo, Atm(-/-) mice were more susceptible to pulmonary S. pneumoniae infection in a manner consistent with inflammasome defects. Our data indicate that such defects were due to oxidative inhibition of inflammasome complex assembly. This study reveals an unanticipated function of reactive oxygen species (ROS) in negative regulation of inflammasomes and proposes a theory for the notable susceptibility of AT patients to pulmonary bacterial infection.

  • 289.
    Espaillat, Akbar
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Uncovering novel cell wall chemistries in gram negative bacteria: from development or dedicated peptidoglycan chemometric tools to functional genomics2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacteria are surrounded by an external cell wall whose main component is a polymeric net-like structure called the peptidoglycan (PG) or murein sacculus. PG plays crucial roles in bacterial physiology (eg morphogenesis, growth fitness and regulation of innate immunity). Based on the characteristics of this macromolecule, bacteria are grouped as gram negative and positive. Gram negatives present a thin PG layer in the periplasmic space, while Gram positive bacteria contain one thick multi-layered sacculus covering the cytoplasmic membrane. Although the PG sacculus is widely conserved between bacteria, variations in its chemical structure (ie sugars and peptide components) have been reported as a coping mechanism to stress. For example, V. choleraeis able to downregulate PG biosynthesis through non-canonical D-amino acids (NCDAAs) cell wall editing when entering stationary phase. NCDAAs production relies on Bsr enzymes, broad spectrum racemases which are expressed in V. cholerae under the control of stress sigma factor RpoS. In this thesis, we present a comprehensive study that allows us to determine the basic structural and biochemical features required for prominent D-amino acid production by Bsr enzymes.

    V. cholerae’s PG editing by NCDAAs revealed the existence of previously unappreciated  chemical modification in the cell wall of bacteria. Such an observation made us question whether the latest technology could reveal, otherwise undetectable, novel PG traits and furthermore, revisit the existence of murein in bacteria which were previously defined as PG-less. Finally, these studies would promote a global assessment of the degree of PG-chemical variability at a Kingdom scale.

    On the search for novel functional chemistries and associated mechanisms of cell wall regulation, we analysed the cell wall of hundreds of different species. Here, I present two proof of concept studies: i) investigation of the existence of PG in the Plantomycetes Kuenenia stuttgartiensis, a species previously classified as PG-less; and ii) PG chemical diversity within Class Alphaproteobacteria. To do so, we developed and experimentally validated an innovative chemometric pipeline to rapidly analyse large PG datasets. Chemometric analyses revealed 3 PG clusters within Alphaproteobacteria, which included unprecedented PG modifications widely conserved in family Acetobacteria: amidation at the α-(L)-carboxyl of meso-diaminopimelic acid and the presence of (1–3) cross-linked muropeptides between L-Ala and D-(meso)-diaminopimelate residues from adjacent moieties. Fluctuations of the relative abundance of these PG traits were growth phase and media composition dependent. Functional studies demonstrated that Acetobacteria atypical muropeptides enabled cellular protection against Type VI secreted endopeptidases and negatively affected innate immune system recognition suggesting relevant functional roles in the environmental adaptability of these bacteria.

  • 290.
    Espaillat, Akbar
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Carrasco-Lopez, Cesar
    Bernardo-Garcia, Noelia
    Pietrosemoli, Natalia
    Otero, Lisandro H.
    Alvarez, Laura
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    de Pedro, Miguel A.
    Pazos, Florencio
    Davis, Brigid M.
    Waldor, Matthew K.
    Hermoso, Juan A.
    Cava, Felipe
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Structural basis for the broad specificity of a new family of amino-acid racemases2014In: Acta Crystallographica Section D: Biological Crystallography, ISSN 0907-4449, E-ISSN 1399-0047, Vol. 70, p. 79-90Article in journal (Refereed)
    Abstract [en]

    Broad-spectrum amino-acid racemases (Bsrs) enable bacteria to generate noncanonical D-amino acids, the roles of which in microbial physiology, including the modulation of cell-wall structure and the dissolution of biofilms, are just beginning to be appreciated. Here, extensive crystallographic, mutational, biochemical and bioinformatic studies were used to define the molecular features of the racemase BsrV that enable this enzyme to accommodate more diverse substrates than the related PLP-dependent alanine racemases. Conserved residues were identified that distinguish BsrV and a newly defined family of broad-spectrum racemases from alanine racemases, and these residues were found to be key mediators of the multispecificity of BrsV. Finally, the structural analysis of an additional Bsr that was identified in the bioinformatic analysis confirmed that the distinguishing features of BrsV are conserved among Bsr family members.

  • 291. Fabrik, Ivo
    et al.
    Härtlova, Anetta
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Rehulka, Pavel
    Stulik, Jiri
    Serving the new masters: dendritic cells as hosts for stealth intracellular bacteria2013In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 15, no 9, p. 1473-1483Article in journal (Refereed)
  • 292.
    Fahlgren, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Westermark, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Akopyan, Karen
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Fällman, Maria
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cell type-specific effects of Yersinia pseudotuberculosis virulence effectors2009In: Cellular Microbiology, ISSN 1462-5814, E-ISSN 1462-5822, Vol. 11, no 12, p. 1750-1767Article in journal (Refereed)
    Abstract [en]

    One important feature of Yersinia pseudotuberculosis that enables resistance against the host immune defence is delivery of the antiphagocytic effectors YopH and YopE into phagocytic cells. The tyrosine phosphatase YopH influences integrin signalling, and YopE impairs cytoskeletal dynamics by inactivating Rho GTPases. Here, we report the impact of these effectors on internalization by dendritic cells (DCs), which internalize antigens to orchestrate host immune responses. We found that this pathogen resists internalization by DCs via YopE. YopH that is important for blocking phagocytosis by macrophages and neutrophils and which is also present inside the DCs does not contribute to the resistance. However, the YopH targets Fyb and p130Cas show higher expression levels in macrophages than in DCs. Furthermore, live cell microscopy revealed that the cells internalize Y. pseudotuberculosis in different ways: the macrophages utilize a locally restricted receptor-mediated zipper mechanism, whereas DCs utilize macropinocytosis involving constitutive ruffling that randomly catches bacteria into membrane folds. We conclude that YopH impacts early phagocytic signalling from the integrin receptor to which the bacterium binds and that this tight receptor-mediated stimulation is absent in DC macropinocytosis. Inactivation of cytoskeletal dynamics by YopE affects ruffling activity and hence also internalization. The different modes of internalization can be coupled to the major functions of these respective cell types: elimination by phagocytosis and antigen sampling.

  • 293. Felgner, S
    et al.
    Frahm, M
    Kocijancic, D
    Rohde, M
    Eckweiler, D
    Bielecka, A
    Bueno, Emilio
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Cava, Felipe
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Abraham, WR
    Curtiss, R
    Häussler, S
    Erhardt, M
    Weiss, S
    aroA-Deficient Salmonella enterica Serovar Typhimurium Is More Than a Metabolically Attenuated Mutant2016In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 7, no 5, article id e01220-16Article in journal (Refereed)
    Abstract [en]

    Recombinant attenuated Salmonella enterica serovar Typhimurium strains are believed to act as powerful live vaccine carriers that are able to elicit protection against various pathogens. Auxotrophic mutations, such as a deletion of aroA, are commonly introduced into such bacteria for attenuation without incapacitating immunostimulation. In this study, we describe the surprising finding that deletion of aroA dramatically increased the virulence of attenuated Salmonella in mouse models. Mutant bacteria lacking aroA elicited increased levels of the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) after systemic application. A detailed genetic and phenotypic characterization in combination with transcriptomic and metabolic profiling demonstrated that Delta aroA mutants display pleiotropic alterations in cellular physiology and lipid and amino acid metabolism, as well as increased sensitivity to penicillin, complement, and phagocytic uptake. In concert with other immunomodulating mutations, deletion of aroA affected flagellin phase variation and gene expression of the virulence-associated genes arnT and ansB. Finally, Delta aroA strains displayed significantly improved tumor therapeutic activity. These results highlight the importance of a functional shikimate pathway to control homeostatic bacterial physiology. They further highlight the great potential of Delta aroA-attenuated Salmonella for the development of vaccines and cancer therapies with important implications for host-pathogen interactions and translational medicine. 

    IMPORTANCE Recombinant attenuated bacterial vector systems based on genetically engineered Salmonella have been developed as highly potent vaccines. Due to the pathogenic properties of Salmonella, efficient attenuation is required for clinical applications. Since the hallmark study by Hoiseth and Stocker in 1981 (S. K. Hoiseth and B. A. D. Stocker, Nature 291:238-239, 1981, http://dx.doi.org/10.1038/291238a0), the auxotrophic Delta aroA mutation has been generally considered safe and universally used to attenuate bacterial strains. Here, we are presenting the remarkable finding that a deletion of aroA leads to pronounced alterations of gene expression, metabolism, and cellular physiology, which resulted in increased immunogenicity, virulence, and adjuvant potential of Salmonella. These results suggest that the enhanced immunogenicity of aroA-deficient Salmonella strains might be advantageous for optimizing bacterial vaccine carriers and immunotherapy. Accordingly, we demonstrate a superior performance of Delta aroA Salmonella in bacterium-mediated tumor therapy. In addition, the present study highlights the importance of a functional shikimate pathway to sustain bacterial physiology and metabolism.

  • 294. Fineran, Peter C.
    et al.
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Memory of viral infections by CRISPR-Cas adaptive immune systems: acquisition of new information2012In: Virology, ISSN 0042-6822, E-ISSN 1096-0341, Vol. 434, no 2, p. 202-209Article, review/survey (Refereed)
    Abstract [en]

    Multiple organisms face the threat of viral infections. To combat phage invasion, bacteria and archaea have evolved an adaptive mechanism of protection against exogenic mobile genetic elements, called CRISPR-Cas. In this defense strategy, phage infection is memorized via acquisition of a short invader sequence, called a spacer, into the CRISPR locus of the host genome. Upon repeated infection, the 'vaccinated' host expresses the spacer as a precursor RNA, which is processed into a mature CRISPR RNA (crRNA) that guides an endonuclease to the matching invader for its ultimate destruction. Recent efforts have uncovered molecular details underlying the crRNA biogenesis and interference steps. However, until recently the step of adaptation had remained largely uninvestigated. In this minireview, we focus on recent publications that have begun to reveal molecular insights into the adaptive step of CRISPR-Cas immunity, which is required for the development of the heritable memory of the host against viruses. 

  • 295. Flentie, Kelly
    et al.
    Harrison, Gregory A.
    Tükenmez, Hasan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Livny, Jonathan
    Good, James A. D.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Sarkar, Souvik
    Zhu, Dennis X.
    Kinsella, Rachel L.
    Weiss, Leslie A.
    Solomon, Samantha D.
    Schene, Miranda E.
    Hansen, Mette R.
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cairns, Andrew G.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Kulén, Martina
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wixe, Torbjörn
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Lindgren, Anders E. G.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Chorell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110.
    Bengtsson, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Krishnan, K. Syam
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hultgren, Scott J.
    Larsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Stallings, Christina L.
    Chemical disarming of isoniazid resistance in Mycobacterium tuberculosis2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 21, p. 10510-10517Article in journal (Refereed)
    Abstract [en]

    Mycobacterium tuberculosis (Mtb) killed more people in 2017 than any other single infectious agent. This dangerous pathogen is able to withstand stresses imposed by the immune system and tolerate exposure to antibiotics, resulting in persistent infection. The global tuberculosis (TB) epidemic has been exacerbated by the emergence of mutant strains of Mtb that are resistant to frontline antibiotics. Thus, both phenotypic drug tolerance and genetic drug resistance are major obstacles to successful TB therapy. Using a chemical approach to identify compounds that block stress and drug tolerance, as opposed to traditional screens for compounds that kill Mtb, we identified a small molecule, C10, that blocks tolerance to oxidative stress, acid stress, and the frontline antibiotic isoniazid (INH). In addition, we found that C10 prevents the selection for INH-resistant mutants and restores INH sensitivity in otherwise INH-resistant Mtb strains harboring mutations in the katG gene, which encodes the enzyme that converts the prodrug INH to its active form. Through mechanistic studies, we discovered that C10 inhibits Mtb respiration, revealing a link between respiration homeostasis and INH sensitivity. Therefore, by using C10 to dissect Mtb persistence, we discovered that INH resistance is not absolute and can be reversed.

  • 296. Fleurie, Aurore
    et al.
    Zoued, Abdelrahim
    Alvarez, Laura
    Hines, Kelly M.
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Xu, Libin
    Davis, Brigid M.
    Waldor, Matthew K.
    A Vibrio cholerae BolA-Like Protein Is Required for Proper Cell Shape and Cell Envelope Integrity2019In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 10, no 4, article id e00790-19Article in journal (Refereed)
    Abstract [en]

    BolA family proteins are conserved in Gram-negative bacteria and many eukaryotes. While diverse cellular phenotypes have been linked to this protein family, the molecular pathways through which these proteins mediate their effects are not well described. Here, we investigated the roles of BolA family proteins in Vibrio cholerae, the cholera pathogen. Like Escherichia coli, V. cholerae encodes two BolA proteins, BolA and IbaG. However, in marked contrast to E. coli, where bolA is linked to cell shape and ibaG is not, in V. cholerae, bolA mutants lack morphological defects, whereas ibaG proved critical for the generation and/or maintenance of the pathogen's morphology. Notably, the bizarre-shaped, multipolar, elongated, and wide cells that predominated in exponential-phase Delta ibaG V. cholerae cultures were not observed in stationary-phase cultures. The V. cholerae Delta ibaG mutant exhibited increased sensitivity to cell envelope stressors, including cell wall-acting antibiotics and bile, and was defective in intestinal colonization. Delta ibaG V. cholerae had reduced peptidoglycan and lipid II and altered outer membrane lipids, likely contributing to the mutant's morphological defects and sensitivity to envelope stressors. Transposon insertion sequencing analysis of ibaG's genetic interactions suggested that ibaG is involved in several processes involved in the generation and homeostasis of the cell envelope. Furthermore, copurification studies revealed that IbaG interacts with proteins containing iron-sulfur clusters or involved in their assembly. Collectively, our findings suggest that V. cholerae IbaG controls cell morphology and cell envelope integrity through its role in biogenesis or trafficking of iron-sulfur cluster proteins. IMPORTANCE BolA-like proteins are conserved across prokaryotes and eukaryotes. These proteins have been linked to a variety of phenotypes, but the pathways and mechanisms through which they act have not been extensively characterized. Here, we unraveled the role of the BolA-like protein IbaG in the cholera pathogen Vibrio cholerae. The absence of IbaG was associated with dramatic changes in cell morphology, sensitivity to envelope stressors, and intestinal colonization defects. IbaG was found to be required for biogenesis of several components of the V. cholerae cell envelope and to interact with numerous iron-sulfur cluster-containing proteins and factors involved in their assembly. Thus, our findings suggest that IbaG governs V. cholerae cell shape and cell envelope homeostasis through its effects on iron-sulfur proteins and associated pathways. The diversity of processes involving ironsulfur-containing proteins is likely a factor underlying the range of phenotypes associated with BolA family proteins.

  • 297. Fleury, Christophe
    et al.
    Su, Yu-Ching
    Hallstroem, Teresia
    Sandblad, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Zipfel, Peter F.
    Riesbeck, Kristian
    Identification of a Haemophilus influenzae Factor H-Binding Lipoprotein Involved in Serum Resistance2014In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 192, no 12, p. 5913-5923Article in journal (Refereed)
    Abstract [en]

    Haemophilus influenzae is a Gram-negative human pathogen that resides in the upper respiratory tract. Encapsulated H. influenzae type b (Hib) and type f (Hif) are the most common serotypes associated with invasive disease. H. influenzae displays various strategies to circumvent the host innate immune response, including the bactericidal effect of the complement system. In this study, we identified an H. influenzae lipoprotein having the ability to bind factor H (FH), the major regulator of the alternative pathway of complement activation. This protein, named protein H (PH), was surface exposed and was found in all clinical Hib and Hif isolates tested. Deletion of the gene encoding for PH (lph) in Hib and Hif significantly reduced the interaction between bacteria and FH. When Hib and Hif PH variants were separately expressed in nontypeable ( unencapsulated) H. influenzae, which did not bind FH, an increased FH affinity was observed. We recombinantly expressed the two PH variants in Escherichia coli, and despite sharing only 56% identical amino acids, both FH-binding Haemophilus proteins similarly interacted with the complement regulator FH short consensus repeats 7 and 18-20. Importantly, Hib and Hif resistance against the bactericidal effect of human serum was significantly reduced when bacterial mutants devoid of PH were tested. In conclusion, we have characterized a hitherto unknown bacterial protein that is crucial for mediating an interaction between the human pathogen H. influenzae and FH. This novel interaction is important for H. influenzae resistance against complement activation and will consequently promote bacterial pathogenesis.

  • 298. Forns, Núria
    et al.
    Baños, Rosa C
    Balsalobre, Carlos
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Juárez, Antonio
    Madrid, Cristina
    Temperature-dependent conjugative transfer of R27: Role of chromosome- and plasmid-encoded Hha and H-NS proteins2005In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 187, no 12, p. 3950-3959Article in journal (Refereed)
    Abstract [en]

    IncHI plasmids encode multiple-antibiotic resistance in Salmonella enterica serovar Typhi. These plasmids have been considered to play a relevant role in the persistence and reemergence of this microorganism. The IncHII plasmid R27, which can be considered the prototype of IncHI plasmids, is thermosensitive for transfer. Conjugation frequency is highest at low temperature (25 to 30 degrees C), decreasing when temperature increases. R27 codifies an H-NS-like protein (open reading frame 164 [ORF164]) and an Hha-like protein (ORF182). The H-NS and Hha proteins participate in the thermoregulation of gene expression in Escherichia coli. Here we investigated the hypothetical role of such proteins in thermoregulation of R27 conjugation. At a nonpermissive temperature (33 degrees C), transcription of several ORFs in both transfer region I (Tra1) and Tra2 from R27 is upregulated in cells depleted of Hha-like and H-NS-like proteins. Both chromosome- and plasmid-encoded Hha and H-NS proteins appear to potentially modulate R27 transfer. The function of R27-encoded Hha-like and H-NS proteins is not restricted to modulation of R27 transfer. Different mutant phenotypes associated with both chromosomal hha and hns mutations are compensated in cells harboring R27.

  • 299.
    Forsberg, Karin
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Jonsson, P Andreas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Andersen, Peter M
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Bergemalm, Daniel
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Graffmo, Karin S
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Hultdin, Magnus
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Jacobsson, Johan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurology.
    Rosquist, Roland
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Novel antibodies reveal inclusions containing non-native SOD1 in sporadic ALS patients2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 7, p. e11552-Article in journal (Refereed)
    Abstract [en]

    Mutations in CuZn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) and are found in 6% of ALS patients. Non-native and aggregation-prone forms of mutant SOD1s are thought to trigger the disease. Two sets of novel antibodies, raised in rabbits and chicken, against peptides spaced along the human SOD1 sequence, were by enzyme-linked immunosorbent assay and an immunocapture method shown to be specific for denatured SOD1. These were used to examine SOD1 in spinal cords of ALS patients lacking mutations in the enzyme. Small granular SOD1-immunoreactive inclusions were found in spinal motoneurons of all 37 sporadic and familial ALS patients studied, but only sparsely in 3 of 28 neurodegenerative and 2 of 19 non-neurological control patients. The granular inclusions were by confocal microscopy found to partly colocalize with markers for lysosomes but not with inclusions containing TAR DNA binding protein-43, ubiquitin or markers for endoplasmic reticulum, autophagosomes or mitochondria. Granular inclusions were also found in carriers of SOD1 mutations and in spinobulbar muscular atrophy (SBMA) patients and they were the major type of inclusion detected in ALS patients homozygous for the wild type-like D90A mutation. The findings suggest that SOD1 may be involved in ALS pathogenesis in patients lacking mutations in the enzyme.

  • 300.
    Forsgren, Stina
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Mechanisms of lymphocyte selection in physiology and autoimmune pathology1991Doctoral thesis, comprehensive summary (Other academic)
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