Functional analysis and screening small molecules to RpfF protein in Xanthomonas oryzae involved in rice bacterial blight disease

Xanthomonas oryzae pv.oryzae(Xoo) is an important rice pathogen.This is a vascular pathogen entering the plant via the hydathodes causing rice bacterial blight.It has been known that most regulation of pathogenicity factor F(RpfF) genes in Xanthomonas regulates virulence in response to the diffusible signal factor(DSF).The RpfF recognized as an attractive drug target in bacterial rice blight disease.In this study,we performed the gene-gene interaction of RpfF and pathway functional analysis.3 D structure of RpfF protein was predicted using a homology modelling tool Swiss-Model and refined by molecular dynamics(MD) simulation.The refined model protein was predicted structural assessment using various tools such as PROCHECK,ERRAT,and VERIFY-3 D.We have collected 2 500 rifampicin analogues from Zinc Database by virtual screening.The screened compounds were docked into the active site of the RpfF protein using AutoDock Vina in PyRx Virtual Screening Tool.Furthermore,docking result and in silico ADMET analysis described that the compounds ZINC03056414,ZINC03205310,ZINC08673779,ZINC09100848,ZINC09729566,ZINC11415953,ZINC12810788,ZINC24989313,ZINC27441787 and ZINC32739565 have best binding energies and less toxicity than reference compound.This study revealed that the active site residues such as HIS-118,HIS-147,THR-148,ARG-179,ASP-207,ARG-240 and THR-244 are key roles in the pathogenicity.It could be beneficial in the design of small molecule therapeutics or the treatment of rice bacterial blight disease.

水稻白叶枯病黄单胞菌rpfF基因的定位及其在致病调控中的作用

检测到水稻白叶枯病菌能产生一种“跨菌调控因子”，在固体平板上，这种因子由白叶枯病菌分泌到细胞外后可以扩散并进入甘蓝黑腐病菌，调控甘蓝黑腐病菌致病因子的表达．本研究从水稻白叶枯病菌中克隆鉴定了一个与这种“跨菌”调控因子合成有关的基因ｒｐｆＦ，通过转座子诱变和标记置换（ｍａｒｋｅｒｅｘｃｈａｎｇｅ）技术，构建了ｒＰｆＦ突变体，突变体丧失了产生这种“跨菌”调控因子的能力，在水稻植株上的致病能力明显减弱，ＤＮＡ序列分析得知ｒｐｆＦ基因编码的产物和大肠杆菌的３－酮脂酰－ＣＯＡ硫解酶（３－ｋｅｔｏａｃｙｌ－ＣＯＡｔｈｉｏｌａｓｅ）同源。

DSF-家族群体感应信号生物合成途径与调控机制研究进展

群体感应是微生物间相互交流的一种重要机制。Diffusible Signaling Factor (DSF)-家族群体感应信号分子存在于多种革兰氏阴性菌中,调控细菌的致病性和适应性。本文首先介绍DSF-家族群体感应信号的结构多样性与保守性、生物合成途径和两类调控机制。DSF家族群体感应信号属于一类长链不饱和脂肪酸,碳水化合物和支链氨基酸是主要合成前体;合成途径主要包括脂肪酸合成循环和兼具脱水酶和硫酯酶活性的RpfF;在黄单胞菌和伯克氏菌中分别存在2种蛋白-蛋白互作机制调控DSF生物合成。随后,综述最新相关研究结果,提出顺式-2-十二碳烯酸(BDSF)可能是野油菜黄单胞菌侵染大白菜过程中所依赖的"活体"群体感应信号。最后,讨论和展望本领域下一步值得研究的关键科学问题。