大丽轮枝菌（Verticillium dahliae VdLs.17）分泌组预测及分析

 【目的】预测并分析大丽轮枝菌基因组范围内的分泌蛋白，为大丽轮枝菌分泌蛋白致病机理的研究奠定基础。【方法】利用已公布的大丽轮枝菌全基因组序列，组合使用生物信息学软件SignalP、TargetP、TMHMM、Big-pi和PROSITE，预测大丽轮枝菌基因组范围内所有分泌蛋白，定义为分泌组。统计分析分泌组中蛋白N-端信号肽特点；应用碳水化合物活性酶类数据库和病原菌-寄主互作蛋白数据库对分泌组蛋白进行注释，预测分泌组中潜在果胶酶、纤维素酶和病原菌寄主互作蛋白；利用真菌激发子的保守结构域，预测分泌组中潜在的激发子蛋白集；应用BLASTP程序比较分析大丽轮枝菌和黑白轮枝菌分泌组，获得大丽轮枝菌相对于黑白轮枝菌特异的分泌蛋白。【结果】大丽轮枝菌分泌组共有922个蛋白。信号肽分析表明，以19个氨基酸为信号肽的蛋白数目最多，非极性氨基酸丙氨酸的出现频率最高，而有带电侧链的氨基酸天冬氨酸和谷氨酸的出现频率最低，信号肽的-3和-1位置上的氨基酸相对保守。大丽轮枝菌分泌组含有158个潜在的碳水化合物活性酶类，其中，包括10个果胶水解酶和14个果胶裂解酶；190个潜在的病原菌-寄主互作蛋白、97个含有RxLxEDQ]模体的蛋白和52个富含半胱氨酸的小分子量分泌蛋白；58个相对于黑白轮枝菌分泌组特异的蛋白。【结论】本文建立了预测大丽轮枝菌分泌组蛋白的方法。分泌组蛋白信号肽长度具有高度的变异性，氨基酸组成多为脂肪族氨基酸，序列在C-端结构域较为保守。分泌组中包含大量潜在的果胶降解酶、病原菌-寄主互作蛋白、RxLxEDQ]模体蛋白和富含半胱氨酸的小分子量蛋白等致病相关蛋白。

Prediction and Analysis of Verticillium dahliae VdLs.17 Secretome

【Objective】The aim of this study was to predict and analyze secretome of Verticillium dahliae, an important soil-born fungal pathogen that causes vascular wilt diseases. 【Method】The softwares SignalP, TargetP, TMHMM, Big-pi and PROSITE were used to predict the sectetome of V. dahliae. Protein databases were used for secretome annotation to find putative pectinase, cellulose and pathogen-host interaction proteins. The proteins with common fungal effector character were investigated by a set of computer algorithms. By using BLASTP, the secretome of V. dahliae and V. albo-atrum was compared to find V. dahliae specifically secreted proteins. 【Result】A total of 922 possible secreted proteins were identified in V. dahliae scretome. The most frequent amino acid in signal peptides is alanine, and the least is glutamic acid and aspartic acid. The amino acid in the position -3 and -1 are very conserved. The secretome is equipped with 158 carbohydrate-active enzymes which include 10 pectic hydrolases and 14 pectic lyases, 190 putative pathogen-host interaction proteins, 97 RxLxEDQ] motif containing proteins and 52 small cysteine-rich secreted proteins, and 58 V. dahliae specifically secreted proteins compared with V. albo-atrum. 【Conclusion】This study has provided secretome prediction algorithms for V. dahliae. Length of signal peptides vary greatly. Composition of signal peptides are mainly aliphatic amino acid and sequences of signal peptides near C-terminal are conservative. V. dahliae secretome are rich in potential pectinase, pathogen–host interaction protein, RxLxEDQ] motif containing protein and small cysteine-rich protein which may play roles in V. dahliae pathogenetic mechanism.