Molecular characterization of fprB (ferredoxin-NADP+ reductase) in Pseudomonas putida KT2440.
The fpr gene, which encodes a ferredoxin-NADP+ reductase, is known to participate in the reversible redox reactions between NADP+/NADPH and electron carriers, such as ferredoxin or flavodoxin. The role of Fpr and its regulatory protein, FinR, in Pseudomonas putida KT2440 on the oxidative and osmotic stress responses has already been characterized [Lee at al. (2006). Biochem. Biophys. Res. Commun. 339, 1246-1254]. In the genome of P. putida KT2440, another Fpr homolog (FprB) has a 35.3% amino acid identity with Fpr. The fprB gene was cloned and expressed in Escherichia coli. The diaphorase activity assay was conducted using purified FprB to identify the function of FprB. In contrast to the fpr gene, the induction of fprB was not affected by oxidative stress agents, such as paraquat, menadione, H2O2 and t-butyl hydroperoxide. However, a higher level of fprB induction was observed under osmotic stress. Targeted disruption of fprB by homologous recombination resulted in a growth defect under high osmotic conditions. Recovery of oxidatively damaged aconitase activity was faster for the fprB mutant than for the fpr mutant, yet still slower than that for the wild type. Therefore, these data suggest that the catalytic function of FprB may have evolved to augment the function of Fpr in P. putida KT2440.
Division of Environmental Science and Ecological Engineering, Korea University, Seoul 136-701, Korea.
Yunho
Y
Lee
Jinki
J
Yeom
Yoon-Suk
YS
Kang
Juhyun
J
Kim
Jung-Suk
JS
Sung
Che Ok
CO
Jeon
Woojun
W
Park
D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D007700:Kinetics; D009997:Osmotic Pressure; D018384:Oxidative Stress / Q000502:physiology*; D016958:Pseudomonas putida / Q000201:enzymology* / Q000254:growth & development*
D005287:Ferredoxin-NADP Reductase