Control of singlet oxygen-induced oxidative damage in Escherichia coli.
Singlet oxygen ((1)O(2)) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. The oxyR gene product regulates the expression of the enzymes and proteins that are needed for cellular protection against oxidative stress. In this study, the role of oxyR in cellular defense against a singlet oxygen was investigated using Escherichia coli oxyR mutant strains. Upon exposure to methylene blue and visible light, which generates singlet oxygen, the oxyR overexpression mutant was much more resistant to singlet oxygen-mediated cellular damage when compared to the oxyR deletion mutant in regard to growth kinetics, viability and protein oxidation. Induction and inactivation of major antioxidant enzymes, such as superoxide dismutase and catalase, were observed after their exposure to a singlet oxygen generating system in both oxyR strains. However, the oxyR overexpression mutant maintained significantly higher activities of antioxidant enzymes than did the oxyR deletion mutant. These results suggest that the oxyR regulon plays an important protective role in singlet oxygen-mediated cellular damage, presumably through the protection of antioxidant enzymes.
Kim
Sun Yee
SY
Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu 702-701, Korea.
Kim
Eun Ju
EJ
Park
Jeen-Woo
JW
D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D008027:Light; D008751:Methylene Blue; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D000975:Antioxidants; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C499299:oxyR protein, E coli; D026082:Singlet Oxygen; D002374:Catalase; D013482:Superoxide Dismutase; D008751:Methylene Blue