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为深入了解玉米弯孢叶斑病菌致病的分子机制,采用信号肽分析软件Signal P 4.1与PSORTb 3.0.2、跨膜螺旋结构分析软件TMHMM 2.0与THUMBUP、GPI锚定位点分析软件big-PI Predictor和亚细胞器蛋白定位分析软件Target P 1.1这6款软件综合预测该菌全基因组中10 372条蛋白序列,并对筛选出的分泌蛋白信号肽基本特征进行分析。结果表明,在玉米弯孢叶斑病菌全基因组编码蛋白中共发现804个具有典型信号肽的分泌蛋白,占全基因组蛋白总数的7.8%;编码这些蛋白的开放阅读框最小为219 bp,最大为7 113 bp,平均为1 252 bp;引导它们的信号肽长度分布在13~37 aa之间,平均为19 aa。信号肽中出现频率最高的氨基酸依次为丙氨酸、亮氨酸和丝氨酸。信号肽切割位点与根癌土壤杆菌、粗糙脉孢霉和马铃薯晚疫病菌一样,同属于A-X-A型。70个具有功能描述的分泌蛋白主要是和细胞代谢与转运、信号转导有关的酶类;还有一些降解细胞壁组分及与致病相关的酶类,可能与玉米弯孢叶斑病菌的毒性有关。
In order to further understand the molecular mechanism of pathogenicity of Curvularia lunata, the signal peptide analysis software Signal P 4.1 and PSORTb 3.0.2, the transmembrane helix structure analysis software TMHMM 2.0 and THUMBUP, the GPI anchor site analysis software big-PI Predictor And Target P 1.1, a subcellular organelle protein localization analysis software, were used to predict 10 372 protein sequences in the whole genome of the bacterium and to analyze the basic characteristics of the selected secretion protein signal peptide. The results showed that a total of 804 secreted proteins with typical signal peptides were found in the genome-wide-encoded proteins of Curvularia lunata, accounting for 7.8% of the total genome proteins. The minimum open reading frame of these proteins was 219 bp with a maximum of 7 113 bp with an average of 1 252 bp. The lengths of the signal peptides that guide them ranged from 13 to 37 aa with an average of 19 aa. The most frequently occurring amino acids in the signal peptide were alanine, leucine and serine. Signal peptide cleavage sites are the same as those of Agrobacterium tumefaciens, Neurospora crassa, and Phytophthora infestans, belonging to the A-X-A type. Seventy-one secreted proteins with functional description were mainly related to the metabolism and transport of cells, and signal transduction-related enzymes. Some of the enzymes that degraded cell wall components and pathogenicity might be related to the toxicity of Curvularia lunata related.