2kqx
From Proteopedia
NMR structure of the J-domain (residues 2-72) in the Escherichia coli CbpA
Structural highlights
Function[CBPA_ECOLI] DNA-binding protein that preferentially recognizes a curved DNA sequence. It is probably a functional analog of DnaJ; displays overlapping activities with DnaJ, but functions under different conditions, probably acting as a molecular chaperone in an adaptive response to environmental stresses other than heat shock. Lacks autonomous chaperone activity; binds native substrates and targets them for recognition by DnaK. Its activity is inhibited by the binding of CbpM.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedCbpA, 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. Structural basis of the regulation of the CbpA co-chaperone by its specific modulator CbpM.,Sarraf NS, Baardsnes J, Cheng J, O'Connor-McCourt M, Cygler M, Ekiel I J Mol Biol. 2010 Apr 23;398(1):111-21. Epub 2010 Mar 10. PMID:20226195[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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