拓扑异构酶的结构、功能与进化的结构生物信息学研究
文献类型：学位论文
| 作者 | 任永明 |
| 学位类别 | 硕士 |
| 答辩日期 | 2004-08 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 黄京飞 |
| 关键词 | 拓扑异构酶 蛋白质序列 结构域 分子进化 |
| 中文摘要 | 拓扑异构酶（topoisomerase）是一类控制和修改双螺旋DNA复制和转录过程中的拓扑结构的酶，是生命活动中最重要的酶。以IA类和II类拓扑异构酶中共存的toprim以及CAP-like结构域为研究对象，对拓扑异构酶中的三大类酶的分子进化情况进行了分析。结果显示在IA类和II类酶之间序列保守性很低，但是具有两个保守的结构域，在IIB类拓扑异构酶中toprim结构域中存在着和其他toprim结构域相同的四个保守位点，而在CAP-like结构域中IA类和II类中存在较大差异，没有明显的序列保守性，IIB类和IIA类的CAP-like结构域在二级结构上非常相似。从toprim结构域系统进化研究中我们发现IIA类和皿类中toprim结构域的进化关系很近，两类酶的toprim结构域在亲缘关系上和primase较远，而以上三者和IA类的进化关系最远。CAP-like结构域的系统进化研究发现IIA类以及IA类的domain4的CAP-like结构域进化关系比较近，IIB类和他们之间关系稍微远一些，IA类的domain3和以上几个结构域的关系较远，这也与他们的二级结构上的一致性是相同的。通过分析，IIA、IIB类起源于类似IA类的古老的拓扑异构酶，'在IA类进化中经过基因复制产生了两个不同的CAP-like结构域。然后祖先拓扑异构酶发生了变化，N'端加入了ATPase结构域和DNAgyrase/Mutlsecond结构域，形成了严格依赖ATP供能的真核生物IIA类，在细菌中断开成为两个亚基的细菌中IIA类。IIB类是祖先细胞的IIA类的一个或者是两个亚单位在古细菌以及真核生物中通过复制、重组和缺失造成的，IIB类中的toprim结构域很接近IIA类，可以认为，llB类中的toPrim结构域直接由IIA类转移而来，而IIB类中的cAP一1汰e结构域较IIA类中产生更早一些，应该是由拓扑异构酶祖先中产生的二级结构为aβaaββ的CAP-like结构域直接进化而来。然而，两个结构域的基因在连接到一起时候发生了不同于一般顺序的拼接，于是nB类中两个结构域形成了不同于现在的IA类和IIA类的顺序。 |
| 英文摘要 | Topoisomerase is a kind of most important enzymes that control and modify the topological structure in the process of replication and transcription of double-helix DNA. We use toprim and CAP-like domains that can be found in type IA and type II to analyse the molecular evolution of these three types of topoisomerases. The result indicates that there are two conserved domains in type IA and type II. There are four conserved sites in type IIB topoisomerase, as well as in type IA and type IIA, while in CAP-like domain, we can infer that the secondary structure similarity and the sequences similarity of type IA^ IIA and IIB are very weak. The secondary structure of CAP-like domain of the active one(domain3) in type IA and type IIB are very different, but the secondary structures of CAP-like domain in domain 4 of type IA is similar to type IIA and in type IIB, and they all have very similar tertiary structures. The result of the evolutionary research in toprim domain is that the type IIB and IIA are very closer, and the Primase is remote, but the type IA is far away from them. In CAP-like domain, type IIA and the domain 4 of type IA are closer, type IIB is remote, but the domain 3 of type IA is far away from them, these results accord with their difference of secondary structure. Considering the gene information of these enzymes, we can draw a conclusion that type IIA is evolved from the ancient type lA-like topoisomerase. In the evolution of the ancient topoisomerase, two kinds of CAP-like domains come into being, then an ATPase domain and a DNA gyrase/Mutl second domain added to the N-terminal, so an ATP depended topoisomerase appeared. In eukaryotes, topoisomerase II are evolved directly from it, but it breaks into two subunits in gyrase. Type IIB evolved from type IIA by gene duplication x recombination and losing, so they are very similar in the domain arrangement. The toprim domain in type IIB resembles type IIA very much, but the CAP-like domain in type IIB appears earlier than that in type IIA, therefore, the CAP-like domain in type IIB should be transferred from the ancient topoisomerase horizontally. The different arrangement occurred in the course of gene insertion: the CAP-like domain of type IA insert in front of the toprim domain of type IIB, then the array of these two domains in type IIB is unusual to type IA and type IIA. |
| 语种 | 中文 |
| 公开日期 | 2010-10-15 |
| 源URL | [http://159.226.149.42:8088/handle/152453/6186]  |
| 专题 | 昆明动物研究所_结构生物信息学 |
| 推荐引用方式 GB/T 7714 | 任永明. 拓扑异构酶的结构、功能与进化的结构生物信息学研究[D]. 北京. 中国科学院研究生院. 2004. |
入库方式： OAI收割
来源：昆明动物研究所
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