Increased ATP-dependent proteolytic activity in lon-deficient Escherichia coli strains lacking the DnaK protein.
Extracts made from Escherichia coli null dnaK strains contained elevated levels of ATP-dependent proteolytic activity compared with levels in extracts made from dnaK+ strains. This ATP-dependent proteolytic activity was not due to Lon, Clp, or Alp-associated protease. Comparison of the levels of ATP-dependent proteolytic activity present in lon rpoH dnaK mutants and in lon rpoH dnaK+ mutants showed that the level of ATP-dependent proteolytic activity was elevated in the lon rpoH dnaK mutant strain. These findings suggest that DnaK negatively regulates a new ATP-dependent proteolytic activity, independently of sigma 32. Other results indicate that an ATP-dependent proteolytic activity was increased in a lon alp strain after heat shock. It is not yet known whether the same protease is associated with the increased ATP-dependent proteolytic activity in the dnaK mutants and in the heat-shocked lon alph strain.
Kroh
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HE
Waksman Institute, Rutgers, State University of New Jersey, Piscataway 08854.
Simon
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LD
D049069:ATP-Dependent Proteases; D000255:Adenosine Triphosphate / Q000502:physiology*; D004270:DNA, Circular / Q000502:physiology*; D018105:DNA, Kinetoplast; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000502:physiology; D006868:Hydrolysis; D049070:Protease La; D012697:Serine Endopeptidases / Q000172:deficiency*
D004270:DNA, Circular; D018105:DNA, Kinetoplast; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D000255:Adenosine Triphosphate; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La