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Synchrotron radiation circular dichroism spectroscopy-defined structure of the C-terminal domain of NaChBac and its role in channel assembly

Powl, Andrew M. and O’Reilly, Andrias O. and Miles, Andrew J. and Wallace, Bonnie A. (2010) Synchrotron radiation circular dichroism spectroscopy-defined structure of the C-terminal domain of NaChBac and its role in channel assembly. Proceedings of the National Academy of Sciences of the United States of America 107 (32), pp. 14064-14069. ISSN 0027-8424.

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Official URL: http://dx.doi.org/10.1073/pnas.1001793107

Abstract

Extramembranous domains play important roles in the structure and function of membrane proteins, contributing to protein stability, forming association domains, and binding ancillary subunits and ligands. However, these domains are generally flexible, making them difficult or unsuitable targets for obtaining high-resolution X-ray and NMR structural information. In this study we show that the highly sensitive method of synchrotron radiation circular dichroism (SRCD) spectroscopy can be used as a powerful tool to investigate the structure of the extramembranous C-terminal domain (CTD) of the prokaryotic voltage-gated sodium channel (NaV) from Bacillus halodurans, NaChBac. Sequence analyses predict its CTD will consist of an unordered region followed by an α-helix, which has a propensity to form a multimeric coiled-coil motif, and which could form an association domain in the homotetrameric NaChBac channel. By creating a number of shortened constructs we have shown experimentally that the CTD does indeed contain a stretch of ∼20 α-helical residues preceded by a nonhelical region adjacent to the final transmembrane segment and that the efficiency of assembly of channels in the membrane progressively decreases as the CTD residues are removed. Analyses of the CTDs of 32 putative prokaryotic NaV sequences suggest that a CTD helical bundle is a structural feature conserved throughout the bacterial sodium channel family.

Item Type: Article
Additional Information: Available via Gold Open Access at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2922593/?tool=pmcentrez
Keyword(s) / Subject(s): membrane protein assembly, membrane protein structure, synchrotron radiation circular dichroism (SRCD) spectroscopy, voltage-gated sodium channel, secondary structure
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 07 Feb 2011 11:22
Last Modified: 17 Apr 2013 12:20
URI: http://eprints.bbk.ac.uk/id/eprint/3045

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