Abstract
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters convert chemical energy from ATP hydrolysis to mechanical work for substrate translocation. They function by alternating between two states, exposing the substrate-binding site to either side of the membrane. A key question that remains to be addressed is how substrates initiate the transport cycle. Using x-ray crystallography, we have captured the maltose transporter in an intermediate step between the inward- and outward-facing states. We show that interactions with substrate-loaded maltose-binding protein in the periplasm induce a partial closure of the MalK dimer in the cytoplasm. ATP binding to this conformation then promotes progression to the outward-facing state. These results, interpreted in light of biochemical and functional studies, provide a structural basis to understand allosteric communication in ABC transporters.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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ATP-Binding Cassette Transporters / chemistry*
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ATP-Binding Cassette Transporters / metabolism
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Adenosine Triphosphate / metabolism
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Amino Acid Motifs
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Binding Sites
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Biological Transport, Active
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Catalytic Domain
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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 / metabolism
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / metabolism
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Hydrogen Bonding
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Maltose / metabolism
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Maltose-Binding Proteins / chemistry
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Maltose-Binding Proteins / metabolism
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Models, Biological
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Models, Molecular
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Monosaccharide Transport Proteins / chemistry*
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Monosaccharide Transport Proteins / metabolism
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Periplasm / metabolism
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Protein Conformation
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Protein Multimerization
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Protein Structure, Secondary
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Protein Structure, Tertiary
Substances
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ATP-Binding Cassette Transporters
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Escherichia coli Proteins
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MalF protein, E coli
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MalG protein, E coli
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MalK protein, E coli
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Maltose-Binding Proteins
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Monosaccharide Transport Proteins
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maltose transport system, E coli
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Maltose
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Adenosine Triphosphate
Associated data
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PDB/3PUY
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PDB/3PUZ
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PDB/3PV0