Charge Pair Interactions in Transmembrane Helices and Turn Propensity of the Connecting Sequence Promote Helical Hairpin Insertion
2013 (English)In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 425, no 4, 830-840 p.Article in journal (Refereed) Published
alpha-Helical hairpins, consisting of a pair of closely spaced transmembrane (TM) helices that are connected by a short interfacial turn, are the simplest structural motifs found in multi-spanning membrane proteins. In naturally occurring hairpins, the presence of polar residues is common and predicted to complicate membrane insertion. We postulate that the pre-packing process offsets any energetic cost of allocating polar and charged residues within the hydrophobic environment of biological membranes. Consistent with this idea, we provide here experimental evidence demonstrating that helical hairpin insertion into biological membranes can be driven by electrostatic interactions between closely separated, poorly hydrophobic sequences. Additionally, we observe that the integral hairpin can be stabilized by a short loop heavily populated by turn-promoting residues. We conclude that the combined effect of TM-TM electrostatic interactions and tight turns plays an important role in generating the functional architecture of membrane proteins and propose that helical hairpin motifs can be acquired within the context of the Sec61 translocon at the early stages of membrane protein biosynthesis. Taken together, these data further underline the potential complexities involved in accurately predicting TM domains from primary structures.
Place, publisher, year, edition, pages
2013. Vol. 425, no 4, 830-840 p.
electrostatic interactions, helical hairpin, membrane integration, salt bridge, translocon
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:su:diva-88973DOI: 10.1016/j.jmb.2012.12.001ISI: 000315546500012OAI: oai:DiVA.org:su-88973DiVA: diva2:615872
FunderSwedish e‐Science Research CenterSwedish Foundation for Strategic Research Swedish Research CouncilEU, FP7, Seventh Framework Programme, 201924Vinnova