Download MendeleyStructural basis of the regulation of the CbpA co-chaperone by its specific modulator CbpM.
Sarraf, N.S., Baardsnes, J., Cheng, J., O'Connor-McCourt, M., Cygler, M., Ekiel, I.(2010) J Mol Biology 398: 111-121
- PubMed: 20226195
- DOI: https://doi.org/10.1016/j.jmb.2010.03.006
- Primary Citation of Related Structures:
2KQX - PubMed Abstract:
CbpA, one of the Escherichia coli DnaJ homologues, acts as a co-chaperone in the DnaK chaperone system. Despite its extensive similarity in domain structure and function to DnaJ, CbpA has a unique and specific regulatory mechanism mediated through the small protein CbpM. Both CbpA and CbpM are highly conserved in bacteria. Earlier studies showed that CbpM interacts with the N-terminal J-domain of CbpA inhibiting its co-chaperone activity but the structural basis of this interaction is not known. Here, we have combined NMR spectroscopy, site-directed mutagenesis and surface plasmon resonance to characterize the CbpA/CbpM interaction at the molecular level. We have determined the solution structure of the CbpA J-domain and mapped the residues that are perturbed upon CbpM binding. The NMR data defined a broad region on helices alpha2 and alpha 3 as involved in the interactions. Site-directed mutagenesis has been used to further delineate the CbpA J-domain/CbpM interface. We show that the binding sites of CbpM and DnaK on CbpA J-domain overlap, which suggests a competition between DnaK and CbpM for binding to CbpA as a mechanism for CbpA regulation. This study also provides the explanation for the specificity of CbpM for CbpA versus DnaJ, by identifying the key residues for differential binding.
Organizational Affiliation:
Health Sector, Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec, Canada.
