Abstract
The ClpXP ATPase-protease complex is a major component of the protein quality control machinery in the cell. A ClpX subunit consists of an N-terminal zinc binding domain (ZBD) and a C-terminal AAA+ domain. ClpX oligomerizes into a hexamer with the AAA+ domains forming the base of the hexamer and the ZBDs extending out of the base. Here, we report that ClpX switches between a capture and a feeding conformation. ZBDs in ClpX undergo large nucleotide-dependent block movement towards ClpP and into the AAA+ ring. This motion is modulated by the ClpX cofactor, SspB. Evidence for this movement was initially obtained by the surprising observation that an N-terminal extension on ClpX is clipped by bound ClpP in functional ClpXP complexes. Protease-protection, crosslinking, and light scattering experiments further support these findings.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ATPases Associated with Diverse Cellular Activities
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Adenosine Triphosphatases / chemistry
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Adenosine Triphosphatases / metabolism
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Adenosine Triphosphatases / physiology
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Bacterial Proteins / metabolism
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Biological Transport, Active / physiology
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Endopeptidase Clp / chemistry*
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Endopeptidase Clp / metabolism
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Endopeptidase Clp / physiology*
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Escherichia coli / enzymology
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Escherichia coli / physiology
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Escherichia coli Proteins / chemistry
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Escherichia coli Proteins / metabolism
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Escherichia coli Proteins / physiology
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Molecular Chaperones / chemistry
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Molecular Chaperones / metabolism
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Molecular Chaperones / physiology
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Nucleotides / physiology*
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Peptide Fragments / chemistry*
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Peptide Fragments / physiology*
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Protein Structure, Tertiary
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Serine Endopeptidases / metabolism
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Molecular Chaperones
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Nucleotides
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Peptide Fragments
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Serine Endopeptidases
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ClpP protease, E coli
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ClpP protein, Streptococcus pneumoniae
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Endopeptidase Clp
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Adenosine Triphosphatases
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ClpX protein, E coli
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ATPases Associated with Diverse Cellular Activities