摘要
目的从系统发生学和结构生物信息学的角度探讨脊椎动物白介素17(IL-17)基因的起源及其蛋白质结构。方法从美国国家生物技术信息中心(NCBI)及联合基因组研究所(JGI)数据库搜索得到全部已知的人、斑马鱼和文昌鱼IL-17蛋白质序列,同时从另外几个数据库中搜索得到鸡、海鞘等7种常见模式生物的部分IL-17蛋白质序列。利用MEGA软件为这些蛋白质序列构建系统发生树,并用MODELLER软件预测斑马鱼、文昌鱼、海鞘、线虫IL-17的三维结构,再与已有的人IL-17F晶体结构进行比较分析。结果虽然所有IL-17蛋白质序列中都含有4个保守的可能形成一个"半胱氨酸结"构象的半胱氨酸残基,但文昌鱼展示出两种不同的分布模式,其中一种与脊椎动物的分布模式相似,另一种是文昌鱼自身特有。系统发生树显示,脊椎动物IL-17基因的直系同源(ortholog)在文昌鱼基因组中没有出现,而出现于海鞘基因组中。IL-17蛋白质三维模型的比较结果与系统发生树一致。结论文昌鱼的IL-17可能是IL-17进化的分歧点,脊椎动物IL-17基因的直系同源可能最早出现于尾索动物。
Objective To investigate the origin and protein structures of vertebrate interleukin-17 （IL-17） genes via phylogenetic and bioinformatic approaches. Methods All the known IL-17 protein sequences of human, zebrafish and amphioxus were retrieved from the National Center for Biotechnology Information （NCBI） and Joint Genome Institute （JGI） databases. Also, partial IL-17 sequences from seven other model organisms were collected from several specific databases. MEGA software package was used to reconstruct a phylogenetic tree for these sequences and MODELLER software was used to predict IL-17 three-dimensional models of zebrafish, amphioxus, ciona and caenorhabditis, and these models were then compared with the known crystal structure of human IL-17F. Results Although all the IL-17 protein sequences contained four conservative cysteine residues that may be involved in the formation of a typical cysteine knot, amphioxus IL-17 revealed two different distribution patterns, with one similar to that of vertebrates and one unique to amphioxus. Phylogenetic analysis and cysteine analysis showed that amphioxus genome had no ortholog of vertebrate IL-17 genes, but urochordate ciona genome had it. The structural comparison result of our three-dimensional models supported the phylogenetic tree. Conclusion Amphioxus IL-17 might be the divergent point in the IL-17 evolution. The ortholog of vertebrate IL-17 genes might first appear in urochordates.
出处
《第二军医大学学报》
CAS
CSCD
北大核心
2013年第1期17-23,共7页
Academic Journal of Second Military Medical University
基金
山东省科技发展计划(2012G0021833)~~
