细菌Ⅵ型分泌系统Hcp与VgrG蛋白的共进化分析  

Co-evolution of Hcp and VgrG Proteins of Type Ⅵ Secretion System

作　　者：牛苗静 谢清标[1] 李婷[1] 李春霞[1] 陈银华[1] 陶均[1] NIU Miaojing;XIE Qingbiao;LI Ting;LI Chunxia;CHEN Yinhua;TAO Jun(Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource;Institie of Tropical Agriculture and Forestry, Hainan University, Haikou, Hainan 570228 , China)

机构地区：[1]海南大学海南省热带生物资源可持续利用重点实验室/热带农林学院,海口570228

出　　处：《热带生物学报》2018年第1期90-100,共11页Journal of Tropical Biology

基　　金：海南大学青年科学基金(hdkyxj201701);海南省自然科学基金(20163049'20163050);农业部公益性行业科研专项(201403075)

摘　　要：以组成Ⅵ型分泌系统(T6SS)鞘结构蛋白Hcp和VgrG为研究对象,通过蛋白质序列同源性、进化特征及表达相关性的分析,以了解Hcp和VgrG共进化的特征及其在表达上的相互影响。结果表明:Hcp与其他T6SS结构基因共进化,但VgrG却有很大的随机性。1个细菌可能有多套T6SS,一般1个hcp基因对应1套系统。vgrG的数目变化很大,有的细菌只有1个vgrG基因,有的细菌却多达30个,且与有多少套T6SS没有多大的关系。进化分析表明:Hcp可分为14个类,种间的差异小于种内差异。VgrG在进化上可分为3大类,种间差异也小于种内差异。VgrG多样性可能与其识别并辅助不同效应因子转运有关。共进化分析显示VgrG与Hcp具有一定的共进化特性,可推测单个细菌中相互配对的VgrG与Hcp。表达分析显示,在水稻细菌性条斑病菌RS105中,几乎所有的vgrG都与hcp基因的表达正相关,说明在表达水平不能分析两者之间的进化关系,但可说明RS105中VgrG与Hcp功能的相关性。因此,VgrG与Hcp在进化和功能上具有显著相关性。The Type Ⅵ secretion system（T6SS） is widely distributed amongst diverse Gram-negative bacterial species.The extracellular components of the T6SS,Hcp and VgrG,form a needle-like injection device that resembles the phage tail.Hcp forms hexameric rings（sheath） and VgrG at the distal tip of the sheath forms a tail spike-like cell-puncturing device.The relationship between Hcp and VgrG was analyzed at evolutional and expressional levels.Results showed that Hcp co-evolved with other T6SS genes while VgrG evolved randomly.One bacterial species may encode more than one T6SS.The number of Hcp is often equal to that of T6SS,but VgrG is not at all the case.A bacterium encoding T6SS may have up to 30 vgrG genes which are not related to the number of T6SS.Based on the evolution and homology analysis,Hcp can be classified into 14 types,while VgrG into 3 classes.The orthologs of Hcp and VgrG have higher conservation than the paralogs.The VgrG is believed to act as a carrier of effectors.Thus,the diversity of VgrG might be the reason that a bacterium encodes different effectors to kill different bacterial species.Co-evolution analysis showed that Hcp and VgrG were closely related during evolution,with predictable high affinity partner between Hcp and vgrG genes.Expression analysis showed that expression of almost all VgrG genes was positively correlated with the Hcp genes in Xanthomonas oryzae pv.oryzicola RS105 which encodes 30 VgrGs,indicating the expression of both VgrG and Hcp can not be used for their relation analysis but for functional relation analysis in RS105.The results support that Hcp and VgrG are functional and evolutional partners in Gram-negative bacteria.

关 键 词：革兰氏阴性菌 水稻细菌性条斑病菌 T6SS HCP VgrG 

分 类 号：S718.83[农业科学—林学] Q349.53[生物学—遗传学]