Abnormal growth of polyamine-deficient Escherichia coli mutant is partially caused by oxidative stress-induced damage.
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.
Jung
Il Lae
IL
Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, 305-600, Taejon, South Korea.
Oh
Tae Jeong
TJ
Kim
In Gyu
IG
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*
D000596:Amino Acids; D011073:Polyamines; D010100:Oxygen