[Antioxidative function of katG gene in XXXX ].

@entity5568 @entity1568 @entity26 @entity14441 @entity6475 @entity72585 @entity3587
OBJECTIVE: Catalase-peroxidase KatG can protect bacteria from damage of reactive @entity26 species. This study investigated the antioxidative function of catalase - peroxidase gene katG in @entity14441 3841. METHODS: katG mutant strain of @entity14441 was constructed by homologous recombination. The wild type, katG mutant and @entity6475 were challenged by oxidative stress and symbiotic ability. RESULTS: Under free - living conditions, the katG mutant exhibited no generation time extension. However, cells of the katG strain were @entity72585 oj high concentrations of @entity5568 and were vulnerable after aquick exposure to @entity5568 . The real-time qRT-PCR results showec that katG was expressed independently of exogenous @entity5568 . In contrast, the katG mutant strain displayed higher expres, level of ohrB gene and lower expression level of grxC than the wild type. With regard to symbiotic capacities with @entity3587 , the katG mutant was indistinguishable in root nodule nitrogenase activity and competition nodule ability from the wild type. However, katG gene was expressed significantly lower in bacteroids than that in free-living strains. Besides, the colonization of the @entity3587 rhizosphere by the katG mutant was impaired compared to that of the wild type. CONCLUSION: ThE deletion of katG had nosignificant effect in 3841 under the free-living and symbiosis condition but was essential ir antioxidation and colonization of the @entity3587 rhizosphere. Although katG could not be induced by @entity5568 , it still played acentra role in antioxidation and symbiotic @entity1568 fixation by regulating the antioxidant genes such as ohrB and grxC.
