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【目的】为了阐明水稻白叶枯病菌(Xanthomonas oryzaepv.oryzae,简称Xoo)转录调控因子OxyRxoo对过氧化氢(H2O2)降解途径的调控作用。【方法】本研究对推导的H2O2识别调控基因oxyRxoo进行了基因克隆、序列分析、缺失突变和互补试验及其相关表型的鉴定。【结果】克隆的oxyRxoo基因序列与其它几种病原黄单胞菌的同源序列高度保守。OxyRxoo是LysR家族成员之一,具有PBPb结构域和DNA结合保守结构域(HTH)。用标记交换法构建了△oxyRxoo基因缺失突变体。与野生型菌株PXO99A相比,尽管△oxyRxoo在离体培养条件下的生长无明显变化,但H2O2抗性显著地降低,过氧化物酶(CAT)活性明显下降,基因互补可以使之恢复;过氧化物酶基因表达下调,oxyRxoo自身表达显著上调。【结论】OxyRxoo作为一个重要转录调控因子,调控了Xoo的H2O2降解途径。
【Objective】 The objective of this study was to elucidate the regulatory effect of OxyRxoo, a transcriptional regulator of Xanthomonas oryzaepv. Oryzae (Xoo), on the degradation of hydrogen peroxide (H2O2). 【Methods】 In this study, gene cloning, sequence analysis, deletion mutation, complementation test and identification of their related phenotypes were carried out on oxyrxoo. 【Results】 The cloned oxyRxoo gene sequence was highly conserved among several other homologous sequences of X. aeruginosa. OxyRxoo is a member of the LysR family with a PBPb domain and a DNA binding conserved domain (HTH). The △ oxyRxoo gene deletion mutant was constructed by the marker exchange method. Compared with the wild-type strain PXO99A, the H2O2 resistance was significantly decreased and the activity of peroxidase (CAT) was significantly decreased and the gene complementation could recover, although △ oxyRxoo did not change significantly under in vitro culture. Oxygenase gene expression down-regulated, oxyRxoo self-expression was significantly increased. 【Conclusion】 OxyRxoo regulates the H2O2 degradation pathway of Xoo as an important transcriptional regulator.