Requirement of the Escherichia coli dnaK gene for thermotolerance and protection against H2O2.
Thermotolerance in Escherichia coli is induced by exposing cells to a brief heat shock (42 degrees C for 15 min). This results in resistance to the lethal effect of exposure to a higher temperature (50 degrees C). Mutants defective in the recA, uvrA and xthA genes are more sensitive to heat than the wild-type. However, after development of thermotolerance these mutants are like the wild-type in their heat sensitivity. This suggests that thermotolerance is an inducible response capable of protecting cells from the lethal effects of heat, independently of recA, uvrA and xthA. Thermotolerance does not develop in a dnaK mutant. In addition, the dnaK mutant is sensitive to heat and H2O2, but is resistant to UV irradiation. This implies that the E. coli heat-shock response includes a mechanism that protects cells from heat and H2O2, but not from UV.
Delaney
J M
JM
Department of Microbiology and Immunology, College of Medicine, University of Arizona, Tucson 85724.
D002872:Chromosome Deletion; D004249:DNA Damage; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation; D014466:Ultraviolet Rays
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D006861:Hydrogen Peroxide; C063842:dnaK protein, E coli