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Expression analysis of the fpr (ferredoxin-NADP^(+) reductase) gene in Pseudomonas putida KT2440

Lee, Yun-Ho (Division of Environmental Science and Ecological Engineering, Korea University) , Samuel Pe?a-Llopis ^(b,1) (Department of Genetics and Complex Diseases, Harvard School of Public Health) , Kang, Yoon-Suk (Division of Environmental Science and Ecological Engineering, Korea University) , Shin, Hyeon-Dong (Division of Environmental Science and Ecological Engineering, Korea University) , Bruce Demple (Department of Genetics and Complex Diseases, Harvard School of Public Health) , Eugene L. Madsen (Department of Microbiology, Cornell University) , Jeon, Che-Ok (Environmental Biotechnology National Core Research Center, Gyeongsang National University) , Park, Woo-Jun (Division of Environmental Science and Ecological Engineering, Korea University, Environmental Biotechnology National Core Research Center, Gyeongsang National University)

Plant molecular biology and biotechnology research center Annual report, 2005, 2005, 275-283

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The ferredoxin-NADP^(+) reductase (fpr) participates in cellular defense against oxidative damage. The fpr expression in Pseudomonas putida KT2440 is induced by oxidative and osmotic stresses. FinR, a LysR-type transcriptional factor near the fpr gene in the P. putida KT2440 genome, is required for ...
The ferredoxin-NADP^(+) reductase (fpr) participates in cellular defense against oxidative damage. The fpr expression in Pseudomonas putida KT2440 is induced by oxidative and osmotic stresses. FinR, a LysR-type transcriptional factor near the fpr gene in the P. putida KT2440 genome, is required for induction of the fpr under both conditions. We have shown that the fpr and finR gene products can counteract the effects of oxidative and osmotic stresses. Interestingly, FinR-independent expression occurs either during a long period of incubation with paraquat or with high concentrations of oxidative stress agent. This result indicates that there may be additional regulators present in the P. putida KT2440 genome. In contrast to in vivo expression kinetics of fpr from the plant pethogen, Pseudomonas syringae, the fpr gene from P. putida KT2440 exhibited unusually prolonged expression after oxidative stress. Transcriptional fusion and Northern blot analysis studies indicated that the FinR is negatively autoregulated. Expression of the fpr promoter was higher in minimal media than in rich media during exponential phase growth. Consistent with this result. the fpr and finR mutants had a long lag phase in minimal media in contrast to wild-type growth characteristics. Antioxidants such as ascorbate could increase the growth rate of all tested strains in minimal media. This result confirmed that P. putida KT2440 experienced more oxidative stress during exponential growth in minimal media than in rich media. Endogenous promoter activity of the fpr gene is much higher during exponential growth than during stationary growth. These findings demonstrate new relationships between fpr, finR, and the physiology of oxidative stress in P. putida KT2440. ⓒ 2005 Elsevier Inc. All rights reserved.