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Structure and Cooperativity of the Cytosolic Domain of the CorA Mg 2+ Channel from Escherichia coli

DOI: 10.1016/j.str.2017.05.024 DOI Help

Authors: Michael Lerche (Stockholm University) , Hena Sandhu (Stockholm University) , Lukas Flöckner (Stockholm University) , Martin Högbom (Stockholm University) , Mikaela Rapp (Stockholm University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Structure

State: Published (Approved)
Published: January 2017
Diamond Proposal Number(s): 15806

Abstract: Structures of the Mg2+ bound (closed) and apo (open) states of CorA suggests that channel gating is accomplished by rigid-body motions between symmetric and asymmetric assemblies of the cytosolic portions of the five subunits in response to ligand (Mg2+) binding/unbinding at interfacial sites. Here, we structurally and biochemically characterize the isolated cytosolic domain from Escherichia coli CorA. The data reveal an Mg2+-ligand binding site located in a novel position between each of the five subunits and two Mg2+ ions trapped inside the pore. Soaking experiments show that cobalt hexammine outcompetes Mg2+ at the pore site closest to the membrane. This represents the first structural information of how an analog of hexa-hydrated Mg2+ (and competitive inhibitor of CorA) associates to the CorA pore. Biochemical data on the isolated cytoplasmic domain and full-length protein suggests that gating of the CorA channel is governed cooperatively.

Journal Keywords: CorA; magnesium; transport; channel; gating; cobalt hexammine; ligand; cooperativity

Subject Areas: Biology and Bio-materials

Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography