禾谷镰刀菌cAMP受体类GPCR生物信息学分析

Bioinformatic analysis of cAMP receptor-like GPCRs in Fusarium graminearum

禾谷镰刀菌(Fusarium graminearum)是引起小麦赤霉病的主要致病菌。G蛋白偶联受体(G protein coupled receptors,GPCRs)是一类重要的细胞表面受体,其介导的cAMP信号通路可能参与了禾谷镰刀菌的致病和毒素合成,因此分析cAMP受体类型的GPCRs蛋白的结构及其理化性质对了解GPCRs的功能及其与赤霉病致病的关系具有重要意义。本研究运用生物信息学方法,对禾谷镰刀菌全基因组序列中cAMP类GPCR基因进行了生物信息学分析。发现禾谷镰刀菌中存在5个典型的cAMP受体类型GPCRs:FgcAR1、FgcAR2、FgcAR3、FgcAR4和FgcAR5,均含有7个跨膜结构域,并定位于细胞膜上。除FgcAR1外,其余为疏水性蛋白。蛋白质二级结构分析表明,均含有大量α螺旋,比例在60%左右,FgcAR4和FgcAR5没有β转角,FgcAR1、FgcAR2和FgcAR3也只有较少比例的β转角。这些GPCRs中含有较多的Ser和Thr磷酸化位点。遗传分析表明,禾谷镰刀菌cAMP受体类型的GPCR蛋白与假禾谷镰刀菌及F.langsethiae同源性最高,亲缘关系最近。本研究明确了禾谷镰刀菌中cAMP类GPCR蛋白的理化性质、定位、二级结构、磷酸化位点及进化关系,为了解小麦赤霉病发病机制及以GPCRs为靶标的新型杀菌剂研发奠定了基础。

Fusarium graminearum is a major pathogen to cause wheat scab. G protein coupled receptors （GPCRs） are a class of important cell surface receptors. The cAMP signal pathway mediated by GPCRs may be involved in pathopoiesis of F. graminearum and synthesis of mycotoxin. Studies on the structure and physiological and chemical characters of such proteins will be useful for understanding the function and effect to pathopoiesis of the protein. The cAMP receptors like GPCR genes of F. grarninearum genome sequence were analyzed through bioinformatics approaches. Five typical cAMP receptors like GPCRs, FgcAR1, FgeAR2, FgcAR3, FgcAR4 and FgcAR5, were identified in F. graminearum, which contained seven trans-membrane domain structures and were located on plasma membrane. Four proteins are hydrophobin except for FgcAR1. All of them have lots of α helical with a proportion around 60%, but there is no 13 strand in FgcAR4 and FgeAR5 and precious few of β strand in FgeAR1, FgcAR2 and FgcAR3 with the proportion less than 3%. A certain number of phosphorylation loci of Ser and Thr are involved in the receptor. Genetic relationship analysis showed that the cAR protein in F. graiminearttrn has a high sequence homology and close genetic relationship with that in F. pseudograminearum and F. langsethiae. The study clarified the physiological and chemical characters, location, secondary structure, phosphorylation loci of cAMP Receptor-like GPCRs in F. graminearum and the genetic relationship in Fusarum family, which will facilitate to further understand the mechanism of pathogesis in wheat scab and develop novel fungicide by using GPCRs as drug targets.