Abstract:

The COP9 signalosome and the regulatory lid of the 26S proteasome are both eight-subunit protein complexes which are present in most eukaryotes. There is a one-to-one relationship between the corresponding subunits of the two protein complexes in terms of their size and amino acid sequences. Eight groups of subunits from the COP9 signalosome and the proteasome lid complex of different organisms are collected from all the databases at the NCBI website. The corresponding subunits of COP9 signalosome and proteasome lid complex share at least 12% amino acid identity and some conserved regions, and the conserved sites spread evenly over the entire length of the subunits, suggesting that the two complexes have a common evolutionary ancestor. Phylogenetic analyses based on the amino acid sequences of the corresponding subunits of two protein complexes indicate that every tree consists of two clades. The subunits from one of the two protein complexes of different organisms are grouped into one of the two clades respectively. The sequences of single-cell organisms are always the basal groups to that of multi-cell animal and plant species. These results imply that the duplication/divergence events of COP9 signalosome and regulatory lid of the proteasome genes have occurred before the divergence of single-cell and multi-cell eukaryotes, and the genes of the two complexes are independently evolved. The analyses of dN/dS correlation show significant Pearson’s correlations between 21 and 15 pairs of subunit-encoding sequences within the COP9 signalosome and the proteasome lid complex respectively, suggesting that those subunits pairs might have related functions and interacted with one another, and resulted in coevolution.

COP9 信号传导体与调节盖子复合体的进化
苏红文 瞿礼嘉 陈章良 顾红雅

（北京大学蛋白质工程及植物基因工程国家重点实验室，北京100871）

摘要：COP9信号传导体和 2 6S蛋白酶体的调节盖子复合体皆为含有 8个亚基的蛋白复合体 ,在真核生物体中普遍存在 ,它们的相应亚基在大小和氨基酸序列上具有一一对应关系。从NCBI站点的所有数据库中获得了裂殖酵母、酿酒酵母、线虫、果蝇、哺乳动物和拟南芥等多种生物的复合体的亚基序列共 8组。COP9信号传导体与调节盖子复合体相应亚基之间的氨基酸序列一致性大于 12 % ,它们均具有一些保守的区域 ,而且保守位点分布均匀 ,表明它们来自于同一祖先。在基于氨基酸序列构建的系统发育树中 ,各组序列分别形成两个分支 :一个分支由COP9信号传导体亚基和相似蛋白组成 ,另一分支由相应的调节盖子复合体亚基和相似蛋白构成。各个分支中单细胞生物的序列位于动、植物序列的根部 ,表明COP9信号传导体与调节盖子复合体的基因重复发生在真核单细胞生物和多细胞生物分化以前 ,并且二者的亚基基因沿各自的方向独立进化。几乎所有编码两个蛋白复合体的基因在基因组中均为单拷贝 ,第Ⅴ、Ⅵ组的亚基保守程度最高 ,暗示着它们在复合体中起着关键的作用。对COP9信号传导体和调节盖子复合体的相应亚基基因两两之间进行dN/dS的相关性分析 ,分别鉴定出 2 1和 15对亚基编码序列间具有显著的Pearson相关关系 ,推测其相应亚基间可能通过承担相互关联的重要的生物学功能而协同进化。

关键词：COP9信号传导体；调节盖子复合体；分子进化；Pearson 相关性

通讯作者。E-mail: guhy @ plum.lsc.pku.edu.cn。