title: Defect in expression of heat-shock proteins at high temperature in xthA mutants.
abstract: Escherichia coli mutants lacking exonuclease III (xthA) are defective in the induction of heat-shock proteins upon severe heat-shock treatment (upshift from 30 to 50 degrees C) but not mild heat-shock treatment (upshift from 30 to 42 degrees C). We show that this defect is due to the xthA mutation by complementation. Furthermore, increasing the gene dosage of xthA+ prolongs the synthesis of heat shock proteins seen after a shift to 42 degrees C. Increasing the gene dosage of htpR+ partially suppresses the defect of xthA mutants in the synthesis of heat-shock proteins at 50 degrees C. When an xthA strain was incubated at 42 degrees C before a shift to 50 degrees C, it was then able to carry out the synthesis of heat-shock proteins at 50 degrees C.
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000235:genetics* / Q000502:physiology; D005798:Genes, Bacterial; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006358:Hot Temperature; D009154:Mutation
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III