title: Unique structural modulation of a non-native substrate by cochaperone DnaJ.
abstract: The role of bacterial DnaJ protein as a cochaperone of DnaK is strongly appreciated. Although DnaJ unaccompanied by DnaK can bind unfolded as well as native substrate proteins, its role as an individual chaperone remains elusive. In this study, we demonstrate that DnaJ binds a model non-native substrate with a low nanomolar dissociation constant and, more importantly, modulates the structure of its non-native state. The structural modulation achieved by DnaJ is different compared to that achieved by the DnaK-DnaJ complex. The nature of structural modulation exerted by DnaJ is suggestive of a unique unfolding activity on the non-native substrate by the chaperone. Furthermore, we demonstrate that the zinc binding motif along with the C-terminal substrate binding domain of DnaJ is necessary and sufficient for binding and the subsequent binding-induced structural alterations of the non-native substrate. We hypothesize that this hitherto unknown structural alteration of non-native states by DnaJ might be important for its chaperoning activity by removing kinetic traps of the folding intermediates.
authors: Proteomics and Structural Biology Unit, CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, Delhi 110020, India.
authors: Satyam
authors: S
authors: Tiwari
authors: Vignesh
authors: V
authors: Kumar
authors: Gopal Gunanathan
authors: GG
authors: Jayaraj
authors: Souvik
authors: S
authors: Maiti
authors: Koyeli
authors: K
authors: Mapa
mesh_terms: D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D050956:HSP40 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006868:Hydrolysis; D015151:Immunoblotting; D047468:Immunoprecipitation; D007700:Kinetics; D008958:Models, Molecular; D018832:Molecular Chaperones; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation
chemical_list: C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; C063842:dnaK protein, E coli