Crystal structure of an orthologue of the NaChBac voltage-gated sodium channel.

TitleCrystal structure of an orthologue of the NaChBac voltage-gated sodium channel.
Publication TypeJournal Article
Year of Publication2012
AuthorsZhang, X, Ren, W, DeCaen, P, Yan, C, Tao, X, Tang, L, Wang, J, Hasegawa, K, Kumasaka, T, He, J, Wang, J, Clapham, DE, Yan, N
JournalNature
Volume486
Issue7401
Pagination130-4
Date Published2012 May 20
ISSN1476-4687
KeywordsAlphaproteobacteria, Amino Acid Sequence, Bacterial Proteins, Crystallization, Crystallography, X-Ray, HEK293 Cells, Humans, Ion Channel Gating, Models, Molecular, Molecular Sequence Data, Protein Conformation, Sodium Channels, Structure-Activity Relationship
Abstract

Voltage-gated sodium (Na(v)) channels are essential for the rapid depolarization of nerve and muscle, and are important drug targets. Determination of the structures of Na(v) channels will shed light on ion channel mechanisms and facilitate potential clinical applications. A family of bacterial Na(v) channels, exemplified by the Na(+)-selective channel of bacteria (NaChBac), provides a useful model system for structure-function analysis. Here we report the crystal structure of Na(v)Rh, a NaChBac orthologue from the marine alphaproteobacterium HIMB114 (Rickettsiales sp. HIMB114; denoted Rh), at 3.05 Å resolution. The channel comprises an asymmetric tetramer. The carbonyl oxygen atoms of Thr 178 and Leu 179 constitute an inner site within the selectivity filter where a hydrated Ca(2+) resides in the crystal structure. The outer mouth of the Na(+) selectivity filter, defined by Ser 181 and Glu 183, is closed, as is the activation gate at the intracellular side of the pore. The voltage sensors adopt a depolarized conformation in which all the gating charges are exposed to the extracellular environment. We propose that Na(v)Rh is in an 'inactivated' conformation. Comparison of Na(v)Rh with Na(v)Ab reveals considerable conformational rearrangements that may underlie the electromechanical coupling mechanism of voltage-gated channels.

DOI10.1038/nature11054
Alternate JournalNature
PubMed ID22678295
PubMed Central IDPMC3979295
Grant List / / Howard Hughes Medical Institute / United States
P01 NS072040 / NS / NINDS NIH HHS / United States
T32 HL007572 / HL / NHLBI NIH HHS / United States