期刊
CURRENT OPINION IN STRUCTURAL BIOLOGY
卷 16, 期 4, 页码 432-438出版社
CURRENT BIOLOGY LTD
DOI: 10.1016/j.sbi.2006.06.006
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资金
- NIGMS NIH HHS [R01 GM39447] Funding Source: Medline
The crystal structure of a closed form of the CorA Mg2+ transporter from Thermatoga maritima completes a set of representative structures of transport systems for all of the major biological elements, Mg2+, Ca2+, Na+, K+ and Cl-. The CorA monomer has a C-terminal membrane domain containing two transmembrane segments and a large N-terminal cytoplasmic soluble domain. In the membrane, CorA forms a homopentamer shaped like a funnel. Comparison of the structure of CorA with that of other ion channels and transporters suggests numerous common features, but, as might be predicted from the unique chemistry of the Mg2+ cation, the structure of CorA has several unusual features. Among these are initial binding in the periplasm of a fully hydrated Mg2+ ion; a ring of positive charge external to the ion-conduction pathway at the cytosolic membrane interface; and highly negatively charged helices in the cytosolic domain that appear capable of interacting with the ring of positive charge to facilitate Mg2+ entry. Finally, there are bound Mg2+ ions in the cytosolic domain that are well placed to control the interaction of the ring of positive charge and the negatively charged helices, and thus control Mg2+ entry.
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