Abstract
TolC and its homologous family of proteins are outer membrane factors that are essential for exporting small molecules and toxins across the outer membrane in Gram-negative bacteria. Two open reading frames in the Vibrio vulnificus genome that encode proteins homologous to Escherichia coli TolC, designated TolCV1 and TolCV2, have 51.3% and 29.6% amino acid identity to TolC, respectively. In this study, we show that TolCV1 and TolCV2 functionally and physically interacted with the membrane fusion protein, MacA, a component of the macrolide-specific MacAB-TolC pump of E. coli. We further show that the conserved residues located at the aperture tip region of the α-hairpin of TolCV1 and TolCV2 played an essential role in the formation of the functional MacAB-TolC pump using site-directed mutational analyses. Our findings suggest that these outer membrane factors have conserved tip-to-tip interaction with the MacA membrane fusion protein for action of the drug efflux pump in Gram-negative bacteria.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ATP-Binding Cassette Transporters / genetics
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ATP-Binding Cassette Transporters / metabolism*
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Amino Acid Sequence
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Anti-Bacterial Agents / metabolism*
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Bacterial Outer Membrane Proteins / chemistry
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Bacterial Outer Membrane Proteins / genetics
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Bacterial Outer Membrane Proteins / metabolism*
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Biological Transport
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism
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Macrolides / metabolism*
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Membrane Transport Proteins / genetics
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Membrane Transport Proteins / metabolism
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Molecular Sequence Data
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Protein Structure, Secondary
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Sequence Alignment
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Species Specificity
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Vibrio vulnificus / chemistry
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Vibrio vulnificus / genetics
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Vibrio vulnificus / metabolism*
Substances
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ATP-Binding Cassette Transporters
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Anti-Bacterial Agents
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Bacterial Outer Membrane Proteins
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Bacterial Proteins
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Escherichia coli Proteins
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Macrolides
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Membrane Transport Proteins
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tolC protein, E coli