title: Balance of ATPase stimulation and nucleotide exchange is not required for efficient refolding activity of the DnaK chaperone.
abstract: The DnaK system from Thermus thermophilus (DnaK(Tth)) exhibits pronounced differences in organisation and regulation to its mesophile counterpart from Escherichia coli (DnaK(Eco)). While the ATPase cycle of DnaK(Eco) is tightly regulated by the concerted action of the two cofactors DnaJ(Eco) and GrpE(Eco), the DnaK(Tth) system features an imbalance in this cochaperone mediated regulation. GrpE(Tth) considerably accelerates the ATP/ADP exchange, but DnaJ(Tth) only slightly stimulates ATPase activity, believed to be a key step for chaperone activity of DnaK(Eco). By in vitro complementation assays, we could not detect significant ATPase-stimulation of orthologous DnaJ(Tth) . DnaKEco or DnaJ(Eco). DnaK(Tth)-complexes as compared to the DnaK(Eco) system, although they were nevertheless active in luciferase refolding experiments. Assistance of protein recovery by DnaK thus seems to be uncoupled of the magnitude of DnaJ mediated ATPase-stimulation.
authors.affiliation: Max-Planck-Institute für medizinische Forschung, Abteilung Biomolekulare Mechanismen, Heidelberg, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Groemping
authors.forename: Ralf
authors.initials: R
authors.lastname: Seidel
authors.forename: Jochen
authors.initials: J
authors.lastname: Reinstein
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006868:Hydrolysis; D008156:Luciferases / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism; D017510:Protein Folding; D016963:Thermus thermophilus / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D009711:Nucleotides; D008156:Luciferases; D000251:Adenosine Triphosphatases; C063842:dnaK protein, E coli