Abstract
In Gram-negative bacteria, the import of essential micronutrients across the outer membrane requires a transporter, an electrochemical gradient of protons across the inner membrane, and an inner membrane protein complex (ExbB, ExbD, TonB) that couples the proton-motive force to the outer membrane transporter. The inner membrane protein TonB binds directly to a conserved region, called the Ton-box, of the transporter. We solved the structure of the cobalamin transporter BtuB in complex with the C-terminal domain of TonB. In contrast to its conformations in the absence of TonB, the Ton-box forms a beta strand that is recruited to the existing beta sheet of TonB, which is consistent with a mechanical pulling model of transport.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Bacterial Outer Membrane Proteins / chemistry*
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Bacterial Outer Membrane Proteins / metabolism
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Biological Transport, Active
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Crystallography, X-Ray
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Escherichia coli
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / metabolism
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Magnetic Resonance Spectroscopy
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Membrane Proteins / chemistry*
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Membrane Proteins / metabolism
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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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Protein Binding
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Protein Conformation
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Protein Structure, Secondary
Substances
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Bacterial Outer Membrane Proteins
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BtuB protein, E coli
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Escherichia coli Proteins
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Membrane Proteins
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Membrane Transport Proteins
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tonB protein, E coli