土地类芽胞杆菌(Paenibacillus terrae)NK3⁃4 EsxA结构与系统发育分析  

Structure and phylogeny analysis of Paenibacillus terrae NK3⁃4 EsxA

作　　者：于文清 闫凤超[2] 刘文志[1,2] 郑桂萍 肖俊杰[1] YU Wenqing;YAN Fengchao;LIU Wenzhi;ZHENG Guiping;XIAO Junjie(College of Life Science,Shangrao Normal University,Shangrao 334001,Jiangxi,China;Heilongjiang Academy of Agricultural Reclamation Sciences,Harbin 150036,China;Heilongjiang Bayi Agricultural University,Daqing 163319,Heilongjiang,China)

机构地区：[1]上饶师范学院生命科学院,江西上饶334001 [2]黑龙江省农垦科学院,哈尔滨150036 [3]黑龙江八一农垦大学,黑龙江大庆163319

出　　处：《生物信息学》2021年第4期270-275,共6页Chinese Journal of Bioinformatics

基　　金：国家自然科学基金项目(No.32060633);黑龙江省自然科学基金项目(No.LH2019C079).

摘　　要：前期研究在植物根际促生菌土地类芽胞杆菌(Paenibacillus terrae)NK3⁃4中发现一个EsxA编码基因,为明确该基因编码的蛋白的性质、结构及系统发生关系,对该基因进行了生物信息学分析。分析表明,该EsxA含有91个氨基酸,分子质量10276.53 Da,理论pI 5.29,分子式为C445H711N125O146S4,弱酸性,亲水,具有WEG保守基序,属于WXG超级家族成员;建模预测表明,自然状态下EsxA形成不对称的同源二聚体,其中每个亚基都由一个β折叠连接两个α螺旋组成,两个α螺旋反向平行排列;二聚体中两个亚基的肽链呈反向排列,所有N末端和C末端均暴露在外,形成棒状表面形态,其中一个亚基的N端的不规则卷曲形成与棒状二聚体垂直的短柱形凸起;系统发育分析显示,EsxA在种内及种间进化关系虽是不保守的,但类芽胞杆菌源的EsxA与病原细菌的EsxA同源性较低,暗示类芽胞杆菌源EsxA可能与病原微生物的EsxA具有截然不同的功能。结果为包括NK3⁃4菌株在内的类芽胞杆菌属EsxA外源分泌表达条件,活性保持及功能的深入研究提供了理论依据。Earlier studies found an EsxA gene in the plant growth⁃promoting rhizobacteria Paenibacillus terrae NK3⁃4.To clarify the properties,structure,and phylogenetic relationship of the EsxA gene coded protein,a series of analyses were conducted using bioinformatics technology.The analysis of basic properties shows that the protein EsxA contained 91 amino acids with a molecular mass of 10276.53 Da,the theoretical pI was 5.29,the molecular formula was C445H711 N125 O146 S4,weakly acidic and hydrophilic,it had a conservative motif of WEG,and was a member of WXG superfamily.Modeling predictions show that EsxA formed an asymmetric homodimer in a natural state,in which each subunit consisted of twoα⁃helices that were connected by aβ⁃sheet,and the twoα⁃helices arranged in antiparallel;the peptide chains of the two subunits in the dimer arranged in reverse,and all N⁃and C⁃terminuses were exposed to form a rod⁃shaped surface morphology.The irregular curl at the N⁃terminus of one subunit formed a short columnar protrusion,perpendicular to the rod⁃shaped dimer.Phylogenetic analysis shows that EsxAs in Paenibacillus had a low homology with that in pathogenic bacteria,although not conservative among Paenibacillus species,which indicates that EsxA in Paenibacillus may have distinct⁃different functions with that in the pathogenic bacteria.The results can provide theoretical bases for the studies of the exogenous secretion expression conditions,activity maintenance,and functions of EsxA in Paenibacillus genus including Paenibacillus terrae NK3⁃4.

关 键 词：土地类芽胞杆菌 EsxA 生物信息学分析 蛋白3D结构 系统发育 

分 类 号：Q71[生物学—分子生物学]