DNA拓扑异构酶Ⅱ与Ⅰ A的进化分析
Evolutionary Analyses of DNA Topoisomerases Ⅱ and ⅠA
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摘要: DNA拓扑异构酶与断开DNA链和改变其拓扑结构有关。先前的研究认为，拓扑异构酶Type ⅡB是由Type ⅡA通过基因的复制、重组和缺失所造成。然而，本研究结果则显示，Type ⅠA与Type ⅡB的进化关系较近，而Type ⅡA与Type ⅡB的关系较远。因此，Type ⅡB可能是由Type ⅠA演化而来，或者说，Type ⅡB是Type ⅠA在古细菌中的特化形式；Type ⅡB可能是由Type ⅡA通过形成Type ⅠA后演化而成的，而不是由Type ⅡA直接通过基因的复制、重组和缺失所造成。在由Type ⅡA演化成为Type ⅠA，最后演化为Type ⅡB的过程中，DNA拓扑异构酶的催化机制也发生了变化：从需要金属离子的协助，演化到了不需要镁离子的存在协助其催化。Abstract: DNA strand scission and topology changes are catalyzed by DNA topoisomerases. Previous studies suggest that Type ⅡB topoisomerase evolved from Type ⅡA by gene duplication, recombination and absence. However, this study shows that the evolutionary relationship between Type ⅠA and ⅡB is closer than that between Type ⅡA and ⅡB. Thus, Type ⅡB is possibly from Type ⅠA, or Type ⅡB is a special form of ⅠA in archaebacteria; Type ⅡB is probably evolved from ⅡA via ⅠA rather than from ⅡA directly. During the evolution of ⅡA to ⅡB via ⅠA, the catalytic mechanisms of DNA topoisomerases have also been changed; that is, metal ions are necessary in the catalyses for both ⅠA and ⅡA, but no ion is needed for ⅡB.
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