摘要
KRAB锌指基因是哺乳动物中最大的转录调控因子家族,它的多数成员在基因组上成簇分布,具有五种不同的亚家族,在功能行使上承担着不同的作用。本文通过对人类、黑猩猩、小鼠、大鼠和狗五种哺乳动物全蛋白质组序列及mRNA组织表达谱分析,验证了C2H2锌指结构在单个KRAB蛋白质中出现的数目多于一般锌指蛋白质;KRAB功能域在各物种中分布显著不同且与分化时间不成正比,这表明KRAB相关功能域多样性在灵长类进化过程中潜在的适应性进化。同时,提出KRAB亚家族进化的路线:即KRAB-Aa为起始家族,Ba由Aa直接演变形成,而Ca,blonga和XRCC三种亚型可能经过Ba或直接从Aa演变形成;此外,锌指结构在单个蛋白质中出现个数伴随KRAB功能域自身的进化路线逐渐递增,反映了KRAB功能域在形成新转录调控因子方面的积极作用。
The largest family of zinc - finger （ZNF） transcription factors comprises those containing the Kruppel - associated box （or KRAB domain）. The members of this family are always clustered in the human genomeo The KRAB domain family has five subfamilies, which play different roles in terms of their function. In this study, we scanned their protein sequences in five mammalian genomes （human, chimpanzee, mouse, rat and dog）. We found that the number of C2H2 - type zinc finger in single KRAB ZNF proteins is more than that in other ZNF proteins. We observed a large difference of KRAB domain in the five species we examined, especially in the human and chimpanzee, suggesting the adaptive evolution of KRAB domain in primates. According to the reconstructed phylogenetic tree using the sequences of zinc fingers in KRAB proteins, we proposed a hypothetical path for KRAB domain evolution： KRAB - Aa, which was the original KRAB domain, evolved to Ba, while KRAB Ca,blonga and XRCC might have evolved from Ba or directly from Aa. According to this hypothetical evolutionary path, we found that C2H2 - type zinc fingers occurred more frequently in KRAB ZNF protein family than in common ZNF protein family. This observation suggests the positive role of KRAB domain in the evolution of this new transcription factor.
出处
《生物信息学》
2009年第3期202-206,211,共6页
Chinese Journal of Bioinformatics
