3jcf

Publication Abstract from PubMed

CorA, the major Mg(2+) uptake system in prokaryotes, is gated by intracellular Mg(2+) (KD approximately 1-2 mM). X-ray crystallographic studies of CorA show similar conformations under Mg(2+)-bound and Mg(2+)-free conditions, but EPR spectroscopic studies reveal large Mg(2+)-driven quaternary conformational changes. Here, we determined cryo-EM structures of CorA in the Mg(2+)-bound closed conformation and in two open Mg(2+)-free states at resolutions of 3.8, 7.1, and 7.1 A, respectively. In the absence of bound Mg(2+), four of the five subunits are displaced to variable extents ( approximately 10-25 A) by hinge-like motions as large as approximately 35 degrees at the stalk helix. The transition between a single 5-fold symmetric closed state and an ensemble of low Mg(2+), open, asymmetric conformational states is, thus, the key structural signature of CorA gating. This mechanism is likely to apply to other structurally similar divalent ion channels.

Cryo-EM Structures of the Magnesium Channel CorA Reveal Symmetry Break upon Gating.,Matthies D, Dalmas O, Borgnia MJ, Dominik PK, Merk A, Rao P, Reddy BG, Islam S, Bartesaghi A, Perozo E, Subramaniam S Cell. 2016 Feb 11;164(4):747-56. doi: 10.1016/j.cell.2015.12.055. PMID:26871634^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.