Saccharomyces cerevisiae inner mitochondrial membrane Mg2+ transporters Mfm1p and Mrs2p-like family
A eukaryotic subfamily belonging to the Escherichia coli CorA-Salmonella typhimurium ZntB_like family (EcCorA_ZntB-like) family of the MIT superfamily of essential membrane proteins involved in transporting divalent cations (uptake or efflux) across membranes. This functionally diverse subfamily includes the inner mitochondrial membrane Mg2+ transporters Saccharomyces cerevisiae Mfm1p/Lpe10p, Mrs2p, and human MRS2/ MRS2L. It also includes a family of Arabidopsis thaliana proteins (AtMGTs) some of which are localized to distinct tissues, and not all of which can transport Mg2+. Structures of the intracellular domain of two EcCorA_ZntB-like family transporters: Vibrio parahaemolyticus and Salmonella typhimurium ZntB form funnel-shaped homopentamers, the tip of the funnel is formed from two C-terminal transmembrane (TM) helices from each monomer, and the large opening of the funnel from the N-terminal cytoplasmic domains. The GMN signature motif of the MIT superfamily occurs just after TM1, mutation within this motif is known to abolish Mg2+ transport through Salmonella typhimurium CorA, and Mrs2p. Natural variants such as GVN and GIN, as in some ZntB family proteins, may be associated with the transport of different divalent cations, such as zinc and cadmium. The functional diversity of MIT transporters may also be due to minor structural differences regulating gating, substrate selection, and transport.
Comment:based on Thermotoga maritima CorA and on partial structures: the intracellular domains of Vibrio parahaemolyticus and Salmonella typhimurium ZntB; contacts at 4A
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