title: Abnormal growth of polyamine-deficient Escherichia coli mutant is partially caused by oxidative stress-induced damage.
abstract: Polyamines participate in numerous cellular processes and are required for normal cell growth in Escherichia coli. In this study, we constructed a new polyamine-deficient E. coli mutant and investigated the physiological function of polyamines during normal aerobic growth conditions. We showed that the requirement for sulfur-containing, branched chain, and aromatic amino acids, which was exhibited in the sodA sodB double mutant faced with severe oxidative stress, was also true of the polyamine-deficient mutant during normal aerobic cell growth. Sorbitol, sucrose, mannose, 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron), an antioxidant that functions as an oxygen radical scavenger including z.rad;O(2)(-), and thiamine partially relieved the cell growth defect caused by polyamine depletion in a dose-dependent manner. As was the case for the cells treated with paraquat, the mutant had an elongated shape compared with the polyamine-proficient wild type. Decreased aeration also relieved the cell growth defect of the polyamine-deficient mutant. Finally, we confirmed that chloromethyl-2('),7(')-dichlorofluorescin diacetate (DCFH-DA), which is oxidized in a fluorescent product in the presence of various oxidants, also fluoresce in the polyamine-deficient cells. These results showed that abnormal growth of the polyamine-deficient E. coli mutant results partially from oxidative stress-induced damage and the mutant thus exhibits the requirement for antioxidant or specific nutritional amino acid during normal aerobic growth.
authors.affiliation: Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, 305-600, Taejon, South Korea.
authors.forename: Il Lae
authors.initials: IL
authors.lastname: Jung
authors.forename: Tae Jeong
authors.initials: TJ
authors.lastname: Oh
authors.forename: In Gyu
authors.initials: IG
authors.lastname: Kim
mesh_terms: D000596:Amino Acids / Q000145:classification / Q000378:metabolism*; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D009154:Mutation; D018384:Oxidative Stress / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D011073:Polyamines / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D011073:Polyamines; D010100:Oxygen