Abstract
Protein export mediated by the general secretory Sec system in Escherichia coli proceeds by a dynamic transfer of a precursor polypeptide from the chaperone SecB to the SecA ATPase motor of the translocon and subsequently into and through the channel of the membrane-embedded SecYEG heterotrimer. The complex between SecA and SecB is stabilized by several separate sites of contact. Here we have demonstrated directly an interaction between the N-terminal residues 2 through 11 of SecA and the C-terminal 13 residues of SecB by isothermal titration calorimetry and analytical sedimentation velocity centrifugation. We discuss the unusual binding properties of SecA and SecB in context of a model for transfer of the precursor along the pathway of export.
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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Adenosine Triphosphatases / chemistry*
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / 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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Escherichia coli / genetics
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism
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Membrane Transport Proteins / chemistry*
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Membrane Transport Proteins / genetics
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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 Interaction Domains and Motifs / genetics*
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Protein Interaction Mapping / methods*
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SEC Translocation Channels
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SecA Proteins
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Thermodynamics
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Membrane Transport Proteins
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SEC Translocation Channels
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SecB protein, Bacteria
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Adenosine Triphosphatases
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SecA Proteins