东方蜜蜂微孢子虫DNA拓扑异构酶Ⅲ的分子特性与系统进化分析

Analysis of molecular characteristics and phyletic evolution of DNA topoisomeraseⅢin Nosema ceranae

利用相关生物信息学软件对东方蜜蜂微孢子虫(Nosema ceranae)的DNA拓扑异构酶3(DTⅢ)进行了理化性质、分子特性、保守基序、结构域和系统进化的分析。结果表明:DTⅢ包含805个氨基酸,分子式为C4267 H6719 N1117 O1240 S34,分子质量约为94.60 ku,脂溶系数为81.84,等电点为9.08,平均亲水系数为-0.595,亲水氨基酸多于疏水氨基酸,不含典型信号肽;含有41个丝氨酸磷酸化位点,23个酪氨酸磷酸化位点及14个苏氨酸磷酸化位点;包含310个α⁃螺旋,117个β⁃折叠,37个β⁃转角及341个无规则卷曲;可同时定位于细胞核、细胞质和线粒体;东方蜜蜂微孢子虫与其他10种微孢子虫的DTⅢ均含有5个相同的保守基序(Motif 1、Motif 2、Motif 3、Motif 4和Motif 5)和2个相同的结构域(Toprim和Topoisom_bac);通过Mega 11.0软件构建东方蜜蜂微孢子虫和其他物种的DTⅢ的系统进化树,结果显示东方蜜蜂微孢子虫与绒鳌蟹肝孢虫(Hepato⁃spora eriocheir)的DTⅢ聚为一支,进化距离最近。研究结果明确了东方蜜蜂微孢子虫DTⅢ的理化性质和分子特性,并揭示东方蜜蜂微孢子虫与绒鳌蟹肠孢虫的DTⅢ亲缘关系最近,DTⅢ在东方蜜蜂微孢子虫和其他微孢子虫中具有较高的保守性。

The physicochemical properties,molecular characteristics,conserved motifs,structural domains and phyletic evolution of DNA topoisomeraseⅢ(DTⅢ)in Nosema ceranae were analyzed using related bioinformatic software.The results demonstrated that DTⅢcontained 805 amino acids and its molecular formula was C4267H6719N1117O1240S34,whose molecular weight,lipid solubility co⁃efficient,isoelectric point and average hydrophilic coefficient were 94.60 ku,81.84.9.08 and-0.595,respectively.DTⅢcontained more hydrophilic amino acids than the hydrophobic ones,and there was no typical signal peptide;it contained 41 serine phosphoryl⁃ation sites,23 tyrosine phosphorylation sites,14 threonine phosphorylation sites as well as 310α⁃helix,117β⁃sheet,37β⁃turn and 341 random coil.DTⅢof N.ceranae were simultaneously localized in nucleus,cytoplasm and mitochondria;it contained 5 conserved motifs(motif 1,2,3,4 and 5)and 2 structural domains(toprim and topoisom_bac)which were identical to other 10 microsporidi⁃an species;DTⅢof N.ceranae and Hepatospora eriocheir were clustered into 1 clade with the closest evolutionary distance.These findings clarified the molecular characteristics of N.ceranae DTⅢ,closest genetic relationship between N.ceranae and H.eriocheir based on DTⅢand highly conserved property of DTⅢin N.ceranae and other microsporidia.