Abstract
The cytoplasmic membrane protein TonB spans the periplasm of the Gram-negative bacterial cell envelope, contacts cognate outer membrane receptors, and facilitates siderophore transport. The outer membrane receptor FhuA from Escherichia coli mediates TonB-dependent import of ferrichrome. We report the 3.3 angstrom resolution crystal structure of the TonB carboxyl-terminal domain in complex with FhuA. TonB contacts stabilize FhuA's amino-terminal residues, including those of the consensus Ton box sequence that form an interprotein beta sheet with TonB through strand exchange. The highly conserved TonB residue arginine-166 is oriented to form multiple contacts with the FhuA cork, the globular domain enclosed by the beta barrel.
Publication types
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Research Support, Non-U.S. Gov't
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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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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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Ferric Compounds / metabolism
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Membrane Proteins / chemistry*
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Membrane 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
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Protein Structure, Tertiary
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Surface Plasmon Resonance
Substances
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Bacterial Outer Membrane Proteins
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Escherichia coli Proteins
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Ferric Compounds
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FhuA protein, E coli
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Membrane Proteins
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tonB protein, E coli