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Rapid and concerted evolution by hypervariability of Megasatellite DNA

大卫星 DNA 的超变性导致快速一致的进化

基本信息

批准号：
16570006
负责人：
SEZUTSU Hideki
金额：
$ 1.92万
依托单位：
Notional Institute of Agrobiological Sciences
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

Megasatellite DNA is newly discovered tandem repetitive sequence range in size from 3-4.7 kb. RS447 megasatellite DNA found on human 4p16.1 consists of 20-100 hypervariable copies of the 4,746 bp unit sequence. Interestingly, RS447 is not junk DNA but has an open reading frame of 1590 bp encoding ubiquitin-specific protease 17 (USP17). In the previous study by genomic southern hybridization, RS447 sequence was well conserved in mammalian species : monkey, dog, cow, rabbit, rat and mouse. The head-to-tail tandem repetitive structure of the RS447 homologs was also confirmed in those species. However, the mouse genome did not have the tandem structure. In addition, the size of the repeating units differs from species to species. The divergence of RS447 homologs suggested that the megasatellite DNA had evolved rapidly.To understand the possible dynamic evolution of the megasatellite DNA, we have studied whether or not the RS447 homolog is in the other organisms by genomic southern blots and by bioinformatics. By genomic southern hybridization analysis, the RS447 homolog was conserved in three primate species, cat, horse, sheep, chicken and carp. Whether the RS447 homologs are repeated tandemly or not was surprisingly differed from species to species. In bioinformatics analysis, we could find the RS447 homologs in genome database of various organisms : e.g.human, chimp, macaque, rat, mouse, cow, dog, chicken, fish, frog, rice, fly and silkworm. The RS447 homologs as ubiquitin-specific protease are thought to be conserved but evolving rapidly. The copy numbers of RS447 homologs are hypervariable among species. On the other hand, the unit sequences of the tandem repeats within species are likely homogeneous by concerted evolution.

巨卫星DNA是新近发现的一种长度为3- 4.7kb的串联重复序列。在人类4p16.1上发现的RS 447巨卫星DNA由4，746 bp单位序列的20-100个高变拷贝组成。有趣的是，RS 447不是垃圾DNA，而是具有1590 bp的开放阅读框，编码泛素特异性蛋白酶17（USP 17）。在先前的基因组Southern杂交研究中，RS 447序列在哺乳动物物种（猴、狗、牛、兔、大鼠和小鼠）中具有很好的保守性。在这些物种中也证实了RS 447同源物的头-尾串联重复结构。然而，小鼠基因组不具有串联结构。此外，重复单元的大小因物种而异。为了了解大卫星DNA可能的动态演化，我们利用基因组Southern杂交和生物信息学方法研究了大卫星DNA中是否存在RS 447同源物。通过基因组Southern杂交分析，RS 447同源物在猫、马、羊、鸡和鲤鱼3种灵长类动物中是保守的。RS 447同源物是否串联重复，令人惊讶的是不同物种之间的差异。在生物信息学分析中，我们可以在各种生物的基因组数据库中找到RS 447的同源物：例如人类、黑猩猩、猕猴、大鼠、小鼠、牛、狗、鸡、鱼、青蛙、水稻、苍蝇和蚕。作为泛素特异性蛋白酶的RS 447同源物被认为是保守的，但进化迅速。RS 447同源物的拷贝数在物种之间是高度可变的。另一方面，物种内串联重复序列的单位序列可能是一致进化的同质性。