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The structure of the prokaryotic cyclic nucleotide-modulated potassium channel MloK1 at 16 A resolution.

TitleThe structure of the prokaryotic cyclic nucleotide-modulated potassium channel MloK1 at 16 A resolution.
Publication TypeJournal Article
Year of Publication2007
AuthorsChiu P-L, Pagel MD, Evans J, Chou H-T, Zeng X, Gipson B, Stahlberg H, Nimigean CM
JournalStructure
Volume15
Issue9
Pagination1053-64
Date Published2007 Sep
ISSN0969-2126
KeywordsAmino Acid Sequence, Crystallography, Cyclic AMP, Microscopy, Electron, Transmission, Models, Molecular, Molecular Sequence Data, Potassium Channels, Protein Conformation, Rhizobium, Sequence Homology, Amino Acid
Abstract

The gating ring of cyclic nucleotide-modulated channels is proposed to be either a two-fold symmetric dimer of dimers or a four-fold symmetric tetramer based on high-resolution structure data of soluble cyclic nucleotide-binding domains and functional data on intact channels. We addressed this controversy by obtaining structural data on an intact, full-length, cyclic nucleotide-modulated potassium channel, MloK1, from Mesorhizobium loti, which also features a putative voltage-sensor. We present here the 3D single-particle structure by transmission electron microscopy and the projection map of membrane-reconstituted 2D crystals of MloK1 in the presence of cAMP. Our data show a four-fold symmetric arrangement of the CNBDs, separated by discrete gaps. A homology model for full-length MloK1 suggests a vertical orientation for the CNBDs. The 2D crystal packing in the membrane-embedded state is compatible with the S1-S4 domains in the vertical "up" state.

DOI10.1016/j.str.2007.06.020
Alternate JournalStructure
PubMed ID17850745
PubMed Central IDPMC2000844
Grant ListR01 GM081653-01 / GM / NIGMS NIH HHS / United States
U54 GM074929 / GM / NIGMS NIH HHS / United States
U54 GM074929-010006 / GM / NIGMS NIH HHS / United States
U54 GM074929-020006 / GM / NIGMS NIH HHS / United States
U54 GM074929-030006 / GM / NIGMS NIH HHS / United States