2KQX

NMR structure of the J-domain (residues 2-72) in the Escherichia coli CbpA

Summary for 2KQX

• Entry DOI: 10.2210/pdb2kqx/pdb
• Descriptor: Curved DNA-binding protein (1 entity in total)
• Functional Keywords: cbpa-j domain, co-chaperone, escherichia coli, chaperone binding protein
• Biological source: Escherichia coli K-12
• Cellular location: Cytoplasm, nucleoid: P36659
• Total number of polymer chains: 1
• Total formula weight: 8733.77

Authors

Ekiel, I. (deposition date: 2009-11-19, release date: 2010-04-21, Last modification date: 2024-05-22)

Primary citation

Sarraf, N.S.,Baardsnes, J.,Cheng, J.,O'Connor-McCourt, M.,Cygler, M.,Ekiel, I.
Structural basis of the regulation of the CbpA co-chaperone by its specific modulator CbpM.
J.Mol.Biol., 398:111-121, 2010

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.

PubMed: 20226195
DOI: 10.1016/j.jmb.2010.03.006

Experimental method

SOLUTION NMR