Guan Wenjing, Wu Maosen, He Chenyang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Wei Sheng Wu Xue Bao. 2009 Jan;49(1):32-7.
To better understand the mechanisms of cyclic di-GMP signaling in Xanthomonas oryzae pv. oryzae (Xoo),the casual pathogen of bacterial blight of rice, molecular identification of Clpxoo.
A putative signal receptor protein was performed through gene cloning, sequencing and deletion analysis.
Sequence analysis showed Clpxoo was a homologue of Crp and Vfr, the cAMP receptor proteins in Escherichia coli and Pseudomonas aeruginosa respectively, which had the cNMP-binding domains (CAP_ED) at N terminal and the DNA-binding domains (HTH_CRP) at C terminal and is highly conserved in the plant-pathogenic Xanthomonas spp. We constructed delta clpxoo through a double crossover recombination and validated by PCR assay, delta clpxoo displayed the reduced motility and extracellular polysaccharide (EPS) production, and increased sensitive to H2O2 toxicity compared with PXO99(A). All these phenotype changes could be partly restored through complementation of mutants by introducing clpxoo. Moreover, we observed no significant changes in production of extracellular cellulase and xylanase in vitro, biofilm formation and induction of hypersensitive response (HR) on non-host tobacco in delta clpxoo compared to PXO99(A).
Therefore, Clpxoo played a role as one of the global regulator in regulation of flagellar motility, EPS production and H2O2 resistance.
为了更好地理解水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae，Xoo）中环状二鸟苷酸信号传导的机制，对Clpxoo进行分子鉴定。
通过基因克隆、测序和缺失分析对一个假定的信号受体蛋白进行研究。
序列分析表明，Clpxoo分别是大肠杆菌和铜绿假单胞菌中cAMP受体蛋白Crp和Vfr的同源物，其N端具有cNMP结合结构域（CAP_ED），C端具有DNA结合结构域（HTH_CRP），在植物致病黄单胞菌属中高度保守。我们通过双交换重组构建了缺失clpxoo，并通过PCR检测进行验证，与PXO99（A）相比，缺失clpxoo的菌株运动性降低、胞外多糖（EPS）产量减少，对H2O2毒性的敏感性增加。通过导入clpxoo对突变体进行互补，所有这些表型变化都可以部分恢复。此外，与PXO99（A）相比，我们观察到缺失clpxoo的菌株在体外胞外纤维素酶和木聚糖酶的产生、生物膜形成以及在非寄主烟草上的过敏反应（HR）诱导方面没有显著变化。
因此，Clpxoo作为全局调节因子之一，在调节鞭毛运动性、EPS产生和H2O2抗性方面发挥作用。
