东方蜜蜂微孢子虫染色体结构维持(SMC)蛋白的分子特性与系统进化分析

    Molecular characteristics and phyletic evolution of structural maintenance of chromosome (SMC) protein in Nosema ceranae

    • 摘要:
      目的 解析东方蜜蜂微孢子虫Nosema ceranae染色体结构维持(Structural maintenance of chromosome,SMC)蛋白的分子特性,鉴定东方蜜蜂微孢子虫和其他物种的SMC的保守基序和结构域,并进行系统进化分析,旨在丰富东方蜜蜂微孢子虫SMC的基本信息,为功能研究的深入开展提供依据。
      方法 使用Expasy网站的相关软件预测和分析SMC的理化性质、信号肽、磷酸化位点、二级结构和三级结构,利用MEME软件鉴定东方蜜蜂微孢子虫和其他物种SMC的保守基序,采用TBtools软件鉴定东方蜜蜂微孢子虫和其他物种SMC的结构域,通过Mega 11.0软件采用邻接法构建东方蜜蜂微孢子虫和其他物种的SMC系统进化树。
      结果 东方蜜蜂微孢子虫SMC包含1 102个氨基酸,分子式为C5787H9418N1526O1771S41,相对分子质量约130 020,脂溶系数为93.49,等电点为8.28,平均亲水系数为−0.740,亲水氨基酸多于疏水氨基酸,不含典型信号肽;包含50个丝氨酸磷酸化位点、26个酪氨酸磷酸化位点及28个苏氨酸磷酸化位点;包含787个α−螺旋、106条β−折叠、49个β−转角及160个无规则卷曲;可同时定位于细胞核、细胞质和线粒体。在东方蜜蜂微孢子虫、海伦脑炎微孢子虫Encephalitozoon hellem、麦格水蚤汉氏孢虫Hamiltosporidium magnivora、颗粒病微孢子虫Nosema granulosis、康氏泰罗汉孢虫Thelohania contejeani、菲尼斯毕罗酵母Piromyces finnis、指间毛廯菌Trichophyton interdigitale、紫色毛廯菌Trichophyton violaceum、发廯菌Trichophyton tonsurans和黑曲霉Aspergillus melleus 的SMC中预测到相同的9个保守基序;东方蜜蜂微孢子虫和上述其他9个物种的SMC中均含有1个SMC_N结构域和1个SMC_hinge结构域。进一步分析发现,东方蜜蜂微孢子虫与菲尼斯毕罗酵母的SMC序列相似性最高(61.96%),与康氏泰罗汉孢虫的SMC序列相似性最低(34.73%);东方蜜蜂微孢子虫与颗粒病微孢子虫的SMC聚为一支,置信度达到99%,进化距离最近。
      结论 本研究明确了东方蜜蜂微孢子虫SMC的分子特性,丰富了SMC的基本信息,并揭示SMC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,为功能研究的深入开展提供了依据。

       

      Abstract:
      Objective  To analyze the molecular characteristics of structural maintenance of chromosome (SMC) protein in Nosema ceranae, identify conserved motifs and structural domains within SMC in N. ceranae and other species followed by phyletic evolution analysis, thus enriching basic information about N. ceranae SMC and offering a basis for further functional study.
      Method Related software on Expasy website were utilized to predict and analyze physical and chemical property, signal peptide, phosphorylation site, secondary structure and tertiary structure of SMC. MEME software was employed to identify conserved motifs within SMC in N. ceranae and other species. TBtools software was used to identify structural domains within SMC. Based on SMC in N. ceranae and other species, phylogenetic tree was constructed with neighbor-joining method by Mega 11.0 software.
      Result SMC contained 1 102 amino acids, the molecular formula was C5787H9418N1526O1771S41, the relative molecular weight was approximately 130 020, the lipid solubility coefficient was 93.49, the isoelectric point was 8.28, the average hydrophilic coefficient was −0.740, the number of hydrophilic amino acids was more than that of hydrophobic amino acids, and there was no typical signal peptide. SMC contained 50 serine phosphorylation sites, 26 tyrosine phosphorylation sites and 28 threonine phosphorylation sites. It as well included 787 α-helix, 106 β-sheet, 49 β-turn, and 160 random coil. SMC were simultaneously localized in nucleus, cytoplasm and mitochondria. Furthermore, SMC in N. ceranae, Encephalitozoon hellem, Hamiltosporidium magnivora, Nosema granulosis, Thelohania contejeani, Piromyces finnis, Trichophyton interdigitale, Trichophyton violaceum, Trichophyton tonsurans and Aspergillus melleus all contained nine same conserved motifs and two structural domains such as SMC_N and SMC_hinge. Further investigation indicated that the similarity of amino acid sequences of SMC between N. ceranae and P. finnis was the highest (61.96%), while that between N. ceranae and T. contejeani was the lowest (34.73%); SMC in N. ceranae and N. granulosis were clustered into a branch with the confidence of 99%, and their evolutionary distance was the closest.
      Conclusion The results define the molecular characteristics of N. ceranae SMC and enrich basic information about SMC, disclose that SMC in N. ceranae and other microsporidia are highly consevative, and provide a basis for further functional study.

       

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