title: The Cryo-EM structure of the CorA channel from Methanocaldococcus jannaschii in low magnesium conditions.
abstract: CorA channels are responsible for the uptake of essential magnesium ions by bacteria. X-ray crystal structures have been resolved for two full-length CorA channels, each in a non-conducting state with magnesium ions bound to the protein: These structures reveal a homo-pentameric quaternary structure with approximate 5-fold rotational symmetry about a central pore axis. We report the structure of the detergent solubilized Methanocaldococcus jannaschii CorA channel determined by Cryo-Electron Microscopy and Single Particle Averaging, supported by Small Angle X-ray Scattering and X-ray crystallography. This structure also shows a pentameric channel but with a highly asymmetric domain structure. The asymmetry of the domains includes differential separations between the trans-membrane segments, which reflects mechanical coupling of the cytoplasmic domain to the trans-membrane domain. This structure therefore reveals an important aspect of the gating mechanism of CorA channels by providing an indication of how the absence of magnesium ions leads to major structural changes.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Cleverley
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: James
authors.initials: J
authors.lastname: Kean
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: Chitra A
authors.initials: CA
authors.lastname: Shintre
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: Clair
authors.initials: C
authors.lastname: Baldock
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Derrick
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Ford
authors.affiliation: Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK. Electronic address: steve.prince@manchester.ac.uk.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Prince
mesh_terms: D027682:Cation Transport Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D003198:Computer Simulation; D020285:Cryoelectron Microscopy / Q000379:methods; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D008274:Magnesium / Q000737:chemistry*; D063747:Methanocaldococcus / Q000737:chemistry* / Q000648:ultrastructure*; D008956:Models, Chemical; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: D027682:Cation Transport Proteins; C514433:CorA protein, E coli; D029968:Escherichia coli Proteins; D008274:Magnesium
keywords: Channel gating; Cryo-electron microscopy; Ion channel; Membrane protein