Ins and outs of major facilitator superfamily antiporters

• Published in: Annual review of microbiology Vol. 62; p. 289
• Main Authors: Law, Christopher J, Maloney, Peter C, Wang, Da-Neng
• Format: Journal Article
• Language: English
• Published: United States 01.01.2008
• Subjects: Antiporters - chemistry; Antiporters - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Binding Sites; Escherichia coli Proteins; Kinetics; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - metabolism; Models, Molecular; Protein Conformation
• ISSN: 0066-4227; 1545-3251
• DOI: 10.1146/annurev.micro.61.080706.093329

The major facilitator superfamily (MFS) represents the largest group of secondary active membrane transporters, and its members transport a diverse range of substrates. Recent work shows that MFS antiporters, and perhaps all members of the MFS, share the same three-dimensional structure, consisting of two domains that surround a substrate translocation pore. The advent of crystal structures of three MFS antiporters sheds light on their fundamental mechanism; they operate via a single binding site, alternating-access mechanism that involves a rocker-switch type movement of the two halves of the protein. In the sn-glycerol-3-phosphate transporter (GlpT) from Escherichia coli, the substrate-binding site is formed by several charged residues and a histidine that can be protonated. Salt-bridge formation and breakage are involved in the conformational changes of the protein during transport. In this review, we attempt to give an account of a set of mechanistic principles that characterize all MFS antiporters.