CbpA, a DnaJ Homolog, Is a DnaK Co-chaperone, and Its Activity Is Modulated by CbpM

The DnaK chaperone system, consisting of DnaK, DnaJ, and GrpE, remodels and refolds proteins during both normal growth and stress conditions. CbpA, one of several DnaJ analogs in Escherichia coli, is known to function as a multicopy suppressor for dnaJ mutations and to bind nonspecifically to DNA an...

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Bibliographic Details
Published in:The Journal of biological chemistry 2004-08, Vol.279 (32), p.33147-33153
Main Authors: Chae, Chi, Sharma, Suveena, Hoskins, Joel R., Wickner, Sue
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - pharmacology
Bacterial Proteins - metabolism
Carrier Proteins - metabolism
Carrier Proteins - physiology
Dimerization
DNA - metabolism
DNA-Binding Proteins - physiology
Escherichia coli
Escherichia coli Proteins - metabolism
Escherichia coli Proteins - physiology
Heat-Shock Proteins - metabolism
HSP40 Heat-Shock Proteins
HSP70 Heat-Shock Proteins - metabolism
Molecular Chaperones
Open Reading Frames
Operon
Plasmids - genetics
Proteins - genetics
Proteins - physiology
Thiosulfate Sulfurtransferase - metabolism
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Summary:The DnaK chaperone system, consisting of DnaK, DnaJ, and GrpE, remodels and refolds proteins during both normal growth and stress conditions. CbpA, one of several DnaJ analogs in Escherichia coli, is known to function as a multicopy suppressor for dnaJ mutations and to bind nonspecifically to DNA and preferentially to curved DNA. We found that CbpA functions as a DnaJ-like co-chaperone in vitro. CbpA acted in an ATP-dependent reaction with DnaK and GrpE to remodel inactive dimers of plasmid P1 RepA into monomers active in P1 DNA binding. Additionally, CbpA participated with DnaK in an ATP-dependent reaction to prevent aggregation of denatured rhodanese. The cbpA gene is in an operon with an open reading frame, yccD, which encodes a protein that has some homology to DafA of Thermus thermophilus. DafA is a protein required for the assembly of ring-like particles that contain trimers each of T. thermophilus DnaK, DnaJ, and DafA. The E. coli YccD was isolated because of its potential functional relationship to CbpA. Purified YccD specifically inhibited both the co-chaperone activity and the DNA binding activity of CbpA, suggesting that YccD modulates the activity of CbpA. We named the product of the yccD gene CbpM for “CbpA modulator.”
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M404862200