Biochemical properties of the Escherichia coli dnaK heat shock protein and its mutant derivatives.
The dnaK protein of Escherichia coli has been shown to possess both autophosphorylating and 5'-nucleotidase activities. The dnaK protein has been shown to bind avidly to ATP, but hydrolyzing it slowly. In vitro autophosphorylation occurs at a threonine residue when either ATP or GTP are used as phosphate donors. The extent of autophosphorylation is low; only a few percent of the molecules are phosphorylated. This activity is stimulated at least tenfold in the presence of Ca2+ ions with either ATP or GTP as the donor. The autophosphorylating activity of the mutant dnaK756 protein in the presence or absence of Ca2+ is reduced compared to that of the wild type.
Cegielska
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Department of Cellular, Viral and Molecular Biology, University of Utah Medical Center, Salt Lake City 84132.
Georgopoulos
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C
D000596:Amino Acids / Q000032:analysis; D002118:Calcium / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation
D000596:Amino Acids; D006360:Heat-Shock Proteins; D006160:Guanosine Triphosphate; D002118:Calcium