title: Thermosensitive phenotype of Escherichia coli mutant lacking NADP+-dependent isocitrate dehydrogenase.
abstract: Heat shock may increase oxidative stress due to increased production of reactive oxygen species and/or the promotion of cellular oxidation events. NADP(+)-dependent isocitrate dehydrogenase (ICDH) in Escherichia coli produces NADPH, an essential reducing equivalent for the antioxidant system. The protective role of ICDH against heat shock in E. coli was investigated in wild-type and ICDH-deficient strains. Upon exposure to heat shock, the viability was lower and the protein oxidation was higher in mutant cells as compared to wild-type cells. Induction and inactivation of antioxidant enzymes were observed after their exposure to heat shock both in wild-type and in mutant cells. However, wild-type cells maintained significantly higher activities of antioxidant enzymes than did mutant cells. These results suggest that ICDH plays an important role as an antioxidant enzyme in cellular defense against heat shock through the removal of reactive oxygen species as well as in the protection of other antioxidant enzymes.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu, Korea.
authors.forename: In Youl
authors.initials: IY
authors.lastname: Choi
authors.forename: Kil In
authors.initials: KI
authors.lastname: Sup
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jeen-Woo
authors.initials: JW
authors.lastname: Park
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D006358:Hot Temperature; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D009249:NADP / Q000378:metabolism*; D018384:Oxidative Stress; D010641:Phenotype; D013696:Temperature; D013997:Time Factors
chemical_list: D000975:Antioxidants; D009249:NADP; D007521:Isocitrate Dehydrogenase