转录调控因子OxyRxoo对水稻白叶枯病菌H2O2降解途径的调控作用

Roles of OxyRxoo, a transcriptional regulator of Xanthomonas oryzae pv. oryzae in regulation of detoxification of hydrogen peroxide

摘要:

摘要：【目的】为了阐明水稻白叶枯病菌(Xanthomonas oryzae pv. 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。

Abstract:

Abstract:[Objective] OxyRxoo is a homologue of OxyR from Xanthomonas oryzae pv. oryzae (Xoo),the pathogen of bacterial blight of rice. To elucidate the role of OxyRxoo in detoxification of hydrogen peroxide.[Methods] OxyRxoo was studied by gene cloning, sequencing, deletion, complement and phenotype analysis. [Result]Compared to those of the wild-type strain PXO99A, there was no difference in bacterial growth in vitro of △oxyRxoo, but △oxyRxoo is more sensitive to H2O2 with reduced catalase activity. In the presence of H2O2, the expression of catalase genes (ahpCxoo, catBxoo, katExoo and srpAxoo) was significantly down-regulated, while the expression of oxyRxoo was up-regulated in △oxyRxoo. [Conclusion] OxyRxoo functions as a transcription regulator in mediating and controlling H2O2 detoxification in Xoo.