title: Interactions within the ClpB/DnaK bi-chaperone system from Escherichia coli.
abstract: ClpB and DnaK form a bi-chaperone system that reactivates strongly aggregated proteins in vivo and in vitro. Previously observed interaction between purified ClpB and DnaK suggested that one of the chaperones might recruit its partner during substrate reactivation. We show that ClpB from Escherichia coli binds at the substrate binding site of DnaK and the interaction is supported by the N-terminal domain and the middle domain of ClpB. Moreover, the interaction between ClpB and DnaK depends on the nucleotide-state of DnaK: it is stimulated by ADP and inhibited by ATP. These observations indicate that DnaK recognizes selected structural motifs in ClpB as "pseudo-substrates" and that ClpB may compete with bona fide substrates of DnaK. We conclude that direct interaction between ClpB and DnaK does not mediate a substrate transfer between the chaperones, it may, however, play a role in the recruitment of the bi-chaperone system to specific recognition sites in aggregated particles.
authors.affiliation: Department of Biochemistry, University of Gdansk, Gdansk, Poland.
authors.forename: Sabina
authors.initials: S
authors.lastname: Kedzierska
authors.forename: Liudmila S
authors.initials: LS
authors.lastname: Chesnokova
authors.forename: Stephan N
authors.initials: SN
authors.lastname: Witt
authors.forename: Michal
authors.initials: M
authors.lastname: Zolkiewski
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D002850:Chromatography, Gel; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry*; D018832:Molecular Chaperones / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D049071:Endopeptidase Clp; C063842:dnaK protein, E coli; C069775:ClpB protein, E coli