title: Escherichia coli DnaJ and GrpE heat shock proteins jointly stimulate ATPase activity of DnaK.
abstract: The products of the Escherichia coli dnaK, dnaJ, and grpE heat shock genes have been previously shown to be essential for bacteriophage lambda DNA replication at all temperatures and for bacterial survival under certain conditions. DnaK, the bacterial heat shock protein hsp70 analogue and putative chaperonin, possesses a weak ATPase activity. Previous work has shown that ATP hydrolysis allows the release of various polypeptides complexed with DnaK. Here we demonstrate that the ATPase activity of DnaK can be greatly stimulated, up to 50-fold, in the simultaneous presence of the DnaJ and GrpE heat shock proteins. The presence of either DnaJ or GrpE alone results in a slight stimulation of the ATPase activity of DnaK. The action of the DnaJ and GrpE proteins may be sequential, since the presence of DnaJ alone leads to an acceleration in the rate of hydrolysis of the DnaK-bound ATP. The presence of GrpE alone increases the rate of release of bound ATP or ADP without affecting the rate of hydrolysis. The stimulation of the ATPase activity of DnaK may contribute to its more efficient recycling, and it helps explain why mutations in dnaK, dnaJ, or grpE genes often exhibit similar pleiotropic phenotypes.
authors.affiliation: Department of Molecular Biology, University of Gdansk, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Liberek
authors.forename: J
authors.initials: J
authors.lastname: Marszalek
authors.forename: D
authors.initials: D
authors.lastname: Ang
authors.forename: C
authors.initials: C
authors.lastname: Georgopoulos
authors.forename: M
authors.initials: M
authors.lastname: Zylicz
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; C068113:GrpE protein, Bacteria; C489400:GrpE protein, E coli; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D000251:Adenosine Triphosphatases; C063842:dnaK protein, E coli