灰色大角间座壳菌(稻瘟病菌)蛋白激酶编码基因中SSR变异及其对蛋白结构的潜在影响

SSR variation in the protein kinase genes and it’s effects on protein structure of rice blast fungus Magnaporthe grisea

病原菌可以利用多种方式激活或者抑制蛋白激酶信号通路来增强其自身侵染力,在病原物与植物互作初期的信号识别和转导中蛋白激酶扮演着重要的角色。已有研究结果表明灰色大角间座壳菌(稻瘟病菌)蛋白激酶基因中含有丰富的SSR。作者通过对灰色大角间座壳菌(稻瘟病菌)基因组中的89个蛋白激酶基因的外显子区、内含子区、5′-UTR和3′-UTR区中的SSR进行了查找和分析,并对编码区中SSR的扩张或收缩对蛋白结构的影响进行了预测。结果表明,SSR在基因的调控区和编码区中的分布是不均一的,且这些基因的外显子区、内含子区、5′-UTR和3′-UTR区中SSR的组成和分布也均不相同;基因的编码区中三碱基和六碱基SSR相对较多,且SSR基序大都表现为GC含量较高,编码的亲水性氨基酸出现的频率也远远高于疏水性氨基酸。通过病菌群体中变异幅度的检测表明,几乎所有的SSR序列都存在多态性。根据灰色大角间座壳菌(稻瘟病菌)自然群体中SSR的变化幅度,对SSR的扩张或收缩对蛋白二级结构的影响进行预测,发现SSR的扩张或收缩都可能对蛋白的结构产生影响。这暗示着SSR的变异在致病相关基因的变异中可能起着十分重要的作用。

A pathogen is usually enhanced its infectivity through activating and repressing protein kinase signal pathway in some way or other. Protein kinases play important roles in signal identification and transduction at the preliminary stage of plant-pathogen interactions. It was showed that there were abundant simple sequence repeats （SSRs） in the protein kinase genes of Magnaporthe grisea. The SSRs were analyzed within the extron, intron, 5 untranslated region （5′-UTR） and 3 untranslated region （3′-UTR） of 89 protein kinase genes, respectively. The effect of SSR expansion and contraction on protein secondary structure was predicted in gene coding regions. As compared with other regions, tri-nucleotide and hexa-nucleotide were more frequently observed in coding region and G＋C content was more abundant in the SSR motifs. In addition, the frequency of hydrophilic amino acids was relatively higher. Depending on the size variation among field isolates of the pathogen, the expansion or contraction of amino acids encoded by SSR sequences potentially affected on secondary structure of protein. The data of this study indicated that the mutation of SSR might play an important role for pathogenic gene mutation.