Abstract
SecA, the dimeric ATPase subunit of protein translocase, contains a DEAD helicase catalytic core that binds to a regulatory C-terminal domain. We now demonstrate that IRA1, a conserved helix-loop-helix structure in the C-domain, controls C-domain conformation through direct interdomain contacts. C-domain conformational changes are transmitted to the DEAD motor and alter its conformation. These interactions establish DEAD motor/C-domain conformational cross-talk that requires a functional IRA1. IRA1-controlled binding/release cycles of the C-domain to the DEAD motor couple this cross-talk to protein translocation chemistries, i.e. DEAD motor affinities for ligands (nucleotides, preprotein signal peptides, and SecYEG, the integral membrane component of translocase) and ATP turnover. IRA1-mediated global co-ordination of SecA catalysis is essential for protein translocation.
Publication types
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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 / metabolism*
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Adenosine Triphosphate / chemistry
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Bacterial Proteins / metabolism*
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Catalysis
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Catalytic Domain
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DNA Mutational Analysis
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Dimerization
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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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Hydrolysis
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Kinetics
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Ligands
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Membrane Proteins / chemistry
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Membrane Transport Proteins / metabolism*
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Models, Biological
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Models, Molecular
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Mutation
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Protein Binding
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Protein Conformation
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Protein Structure, Tertiary
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Protein Transport
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SEC Translocation Channels
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SecA Proteins
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Spectrometry, Fluorescence
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Surface Plasmon Resonance
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Temperature
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Ligands
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Membrane Proteins
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Membrane Transport Proteins
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SEC Translocation Channels
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SecE protein, E coli
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SecG protein, E coli
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SecY protein, E coli
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Adenosine Triphosphate
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Adenosine Triphosphatases
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SecA Proteins