葡萄霜霉菌糖基水解酶基因家族的生物信息学分析

【目的】分析预测葡萄霜霉菌糖基水解酶（Glycoside hydrolases，GHs）基因家族，为深入研究GHs基因在葡萄霜霉菌致病过程中的作用机理提供理论依据。【方法】利用SignalP 5.0 Server、Cluster W、MEGA 6.0和MEME等生物信息学相关软件对已发表的葡萄霜霉菌全基因组60个GHs基因的基本特征、基因组分布特点及其编码蛋白保守基序、结构域和亚细胞定位等进行生物信息学分析。【结果】葡萄霜霉菌60个GHs基因编码的蛋白长度在128~774 aa，且大部分集中在200~500 aa，其中53个蛋白具有信号肽，蛋白质分子量在14.90~85.45 kD，理论等电点（pI）在3.85~10.39；这些基因在基因组中分布不均匀，其中有27个GHs基因存在串联重复和成簇聚集分布现象，数目最多的3个GHs家族（GH131、GH17和GH6）集中分布在7个scaffold中；序列比对和系统发育进化树分析发现，串联重复和成簇聚集分布的GHs基因处于同一个分支中；motif富集分析发现3个不同的motif，且motif2在葡萄霜霉菌GH6、GH17和GH131等3个家族基因中保守，结构域分析推测大部分GHs家族基因均参与细胞壁的生物过程；亚细胞定位预测结果表明，有53个GHs蛋白定位于细胞外，3个定位在细胞质内，4个定位于线粒体上。【结论】葡萄霜霉菌在侵染寄主的过程中可能会分泌多种GHs酶类来破坏细胞壁的结构，以帮助其在寄主植物中成功定殖。

Bioinformatic analysis of glycoside hydrolases gene family in Plasmopara viticola

【Objective】Analyzed and predicted the glycoside hydrolases(GHs) gene family of Plasmopara viticola, and conducted bioinformatics analysis to provide theoretical basis for in-depth study of the molecular mechanism of GHs gene in pathogenicity of downy mildew.【Method】This study used SignalP 5.0 Server, Cluster W, MEGA6.0, MEME and other bioinformatics-related softwares to analyze the basic characteristics and the encoded proteins, genome distribution characteristics, conserved motifs, structural domains and subcellular location of the 60 GHs genes of the published whole genome of P. viticola.【Result】The protein sizes encoded by 60 GHs genes of P. viticola were between 128 and 774 aa, and most of them were concentrated between 200 and 500 aa. Among them, 53 proteins had signal peptides, and the molecular mass of the protein was between 14.90 and 85.45 kD. The theoretical isoelectric points(pI) was between 3.85 and 10.39. These genes were unevenly distributed in the genome. Twenty-seven of them had tandem repeats and clustering distribution, and the 3 GHs families(GH131, GH17 and GH6) with the largest number were concentrated in 7 scaffolds. Moreover, sequence alignment and phylogenetic tree analysis found that these tandem repeats and clusters of GHs genes were in the same phylogenetic tree branch. The motif enrichment analysis found 3 different motifs, and motif2 was conserved in GH6, GH17 and GH131 family genes of P. viticola. The domain analysis speculated that most GHs family genes were involved in the biological process of the cell wall. The subcellular localization prediction results showed that there were 53 GHs proteins located extracellular, 3 localized in the cytoplasm, and 4 localized on the mitochondria.【Conclusion】The results of bioinformatics analysis show that during the process of infecting the host, P. viticola may secrete a variety of GHs enzymes to destroy the structure of the cell wall and help it successfully colonize the host plant. This will clarify the function of the GHs family genes encoded by P. viticola and the molecular mechanism of pathogenicity.