赭曲霉G蛋白偶联受体的鉴定及生物信息学分析

Identification and bioinformatics analysis of G-protein-coupled receptors in Aspergillus ochraceus

摘要:

【目的】预测并分析赭曲霉(Aspergillus ochraceus)中存在的G蛋白偶联受体(G-protein- coupled receptors，GPCRs)的结构特征和理化性质，探究赭曲霉GPCR超家族蛋白的结构及所接收配体的聚类情况以及与其他同源蛋白的进化关系，为深入开展赭曲霉中GPCRs的定位、功能研究提供理论基础，也有望从G蛋白信号途径角度抑制赭曲霉毒素的产生，进一步控制粮食的真菌毒素污染。【方法】基于已经报道的曲霉属典型GPCRs序列，在赭曲霉全基因组中进行BLASTp比对以获取候选GPCRs蛋白。通过SMART及多种软件进行保守结构域，特别是跨膜结构的分析，进一步分析候选序列的理化性质、信号肽、二级结构及亚细胞定位等特征。最后，利用MEGA构建赭曲霉中GPCRs与同源蛋白的系统发育树进行遗传关系的比较。【结果】明确赭曲霉存在 15个具有典型7次跨膜结构的GPCRs蛋白，不存在信号肽及转运肽，均含有较高比例的α螺旋结构，15个蛋白质中有7个定位在细胞膜。赭曲霉中的GPCRs与黄曲霉等曲霉属中相应的同源序列具有较近的亲缘关系。【结论】本研究首次对赭曲霉的GPCR超蛋白家族进行了预测，分析其结构及理化性质，探讨了其与同源蛋白的聚类情况，为深入开展赭曲霉GPCRs的功能研究提供理论基础。

Abstract:

[Objective] This study aims to predict and analyze the structural characteristics and physicochemical properties of G-protein-coupled receptors (GPCRs) in Aspergillus ochraceus and to explore the clustering of GPCR proteins and their evolutionary relationships with the homologous proteins. The findings are expected to lay a theoretical basis of further research on the locations and functions of GPCRs in A. ochraceus, help inhibit ochratoxin production from the perspective of G protein signaling pathway, and further control mycotoxin contamination in grains. [Methods] Candidate GPCR proteins were screened through BLASTp alignment of A. ochraceus genome against the reported typical GPCR sequences of Aspergillus sp. Conserved domains, especially transmembrane domains, were analyzed by SMART and a variety of software. The physicochemical properties, signal peptides, secondary structures, and subcellular localization of the candidate sequences were further analyzed. Finally, MEGA was used to construct a phylogenetic tree of GPCRs in A. ochraceus and homologous proteins, and the genetic relationship was elucidated. [Results] A total of 15 GPCR proteins with typical seven transmembrane helices were found in A. ochraceus, but they had no signal peptides or transit peptides. They all contained a large proportion of α-helices, and 7 of the 15 proteins were located at the cell membrane. GPCRs in A. ochraceus had close genetic relationship with the homologous sequences in A. flavus and other Aspergillus species. [Conclusion] In this study, the GPCRs in A. ochraceus were predicted for the first time. The structures and physicochemical properties of them and the clustering with homologous proteins were analyzed, laying a theoretical basis for further research on the functions of GPCRs in A. ochraceus.