The structural basis of substrate translocation by the Escherichia coli glycerol-3-phosphate transporter: a member of the major facilitator superfamily.
The major facilitator superfamily represents the largest group of secondary active membrane transporters in the cell. The 3.3A resolution structure of a member of this protein superfamily, the glycerol-3-phosphate transporter from the Escherichia coli inner membrane, reveals two domains connected by a long central loop. These N- and C-terminal domains, each containing a six-helix bundle, are related by pseudo-twofold symmetry. A substrate translocation pore is located between the two domains and is open to the cytoplasm. Two arginines at the closed end of the pore comprise the substrate-binding site. Biochemical experiments show that, upon substrate binding, the protein adopts a more compact conformation. The crystal structure suggests that the transporter operates through a single binding site, alternating access mechanism via a rocker-switch type of movement of the N- and C-terminal domains. The structure and mechanism of the glycerol-3-phosphate transporter form a paradigm for other members of the major facilitator superfamily.
Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, New York 10016, USA.
M Joanne
MJ
Lemieux
Yafei
Y
Huang
Da-Neng
DN
Wang
D001665:Binding Sites; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D013329:Structure-Activity Relationship
D029968:Escherichia coli Proteins; C488962:GlpT protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; C063498:UhpT protein, E coli