Genome-wide identification of the Sec-dependent secretory protease genes in Erwinia amylovora and analysis of their expression during infection of immature pear fruit

梨火疫菌Sec依赖分泌蛋白酶的全基因组鉴定及其在侵染幼梨过程中的基因表达分析

The general secretory(Sec)pathway represents a common mechanism by which bacteria secrete proteins,including virulence factors,into the extracytoplasmic milieu.However,there is little information about this system,as well as its associated secretory proteins,in relation to the fire blight pathogen Erwinia amylovora.In this study,data mining revealed that E.amylovora harbors all of the essential components of the Sec system.Based on this information,we identified putative Sec-dependent secretory proteases in E.amylovora on a genome-wide scale.Using the programs SignalP,LipoP,and Phobius,a total of 15 putative proteases were predicted to contain the N-terminal signal peptides(SPs)that might link them to the Sec-dependent pathway.The activities of the predicted SPs were further ttvreaaalicsdyeta otgepelda nsuesmsi inicng cprarenoa psEeesrtdcy h.s eiTrgirncaihfniicsa carcniotplltiyi-obwnahasle enad nEaa.ll kyaaslmiensye lo spvhohorowas epwdh atasht aaust sete h(deP theoo xipAnr)o ecgsueslinaotene f iuofms i1 om1 na tosufyr steth epe em1 a t5 rh s,ae txs tcuroagcngfyeitrsomtipnelagd s ttmhhieecii rr pperoox---xL?tential roles in plant infection.The results of this study support the suggestion that E.amylovora might employ the Sec system to secrete a suite of proteases to enable successful infection of plants,and shed new light on the interaction of E.amylovora with host plants.

目的:鉴定参与梨火疫菌侵染的重要Sec依赖分泌蛋白酶。创新点:构建了梨火疫菌Sec依赖分泌蛋白酶编码基因在侵染寄主植物过程中的时序表达图谱。方法:利用生物信息学与大肠杆菌Pho A检测体系两者结合,在全基因组水平筛选并鉴定梨火疫菌的Sec依赖分泌蛋白酶;利用逆转录实时定量聚合酶链反应(RT-q PCR),分析Sec依赖分泌蛋白酶编码基因在梨火疫菌侵染寄主植物过程中转录表达的时序变化。结论:梨火疫菌含有完整的Sec分泌系统,可由此分泌至少15种蛋白酶,其中11种蛋白酶可能在病原菌侵染寄主植物过程中发挥功能。