Abstract
The major facilitator superfamily represents the largest group of secondary membrane transporters in the cell. Here we report the 3.3 angstrom resolution structure of a member of this superfamily, GlpT, which transports glycerol-3-phosphate into the cytoplasm and inorganic phosphate into the periplasm. The amino- and carboxyl-terminal halves of the protein exhibit a pseudo two-fold symmetry. Closed off to the periplasm, a centrally located substrate-translocation pore contains two arginines at its closed end, which comprise the substrate-binding site. Upon substrate binding, the protein adopts a more compact conformation. We propose that GlpT operates by a single-binding site, alternating-access mechanism through a rocker-switch type of movement.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Biological Transport
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Cell Membrane / chemistry
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Crystallization
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Crystallography, X-Ray
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Escherichia coli / chemistry*
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Escherichia coli / enzymology
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Escherichia coli Proteins / chemistry
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Escherichia coli Proteins / metabolism
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Glycerophosphates / metabolism*
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Helix-Turn-Helix Motifs
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Mass Spectrometry
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Membrane Transport Proteins / chemistry*
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Membrane Transport Proteins / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Periplasm / metabolism
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Phosphates / metabolism
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Protein Conformation
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Protein Folding
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Protein Structure, Secondary
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Protein Structure, Tertiary
Substances
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Escherichia coli Proteins
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GlpT protein, E coli
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Glycerophosphates
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Membrane Transport Proteins
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Phosphates
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alpha-glycerophosphoric acid