STUDIES OF FUNCTIONS INVOLVED IN GENETIC RECOMBINATION

这个项目目前的重点是了解DNA是如何 超螺旋是由DNA旋转酶和相关的酶引起的，并且 目的：研究DNA超螺旋对细菌基因表达的影响。 以下是最近的一些结果： 三磷酸腺苷类似物(β，伽马-亚胺)三磷酸腺苷的结合速度极慢 在三磷酸腺苷的存在下，DNA旋转酶的生成速度大大加快。因此， 矛盾的是，ATP可以帮助类似物阻断ATP结合位点和 抑制这种酶。 DNA超螺旋对细菌转录的影响已经被证实 进一步研究。在DNA松弛诱导的启动子中， 第一个转录区域的结构被证明是重要的； 当DNA超级卷曲时，许多转录本会过早终止， 而全长转录本则是在松弛的DNA上形成的。 嗜热菌反向DNA旋转酶的实验研究 结果表明，与所有其他测试的拓扑异构酶不同，这种酶只能 在一个方向上更改超级卷绕(朝向正超级卷绕)。 反向旋转酶是依赖于ATP的，但可以通过显著的 低浓度的三磷酸腺苷。

The present focus of this project is to understand how DNA supercoiling is brought about by DNA gyrase and related enzymes, and to study the effects of DNA supercoiling on bacterial gene expression. These are some recent results: The extremely slow binding of the ATP analog (beta, gamma-imido) ATP to DNA gyrase is greatly accelerated in the presence of ATP. Thus paradoxically ATP can help the analog to block ATP binding sites and inhibit the enzyme. The effect of DNA supercoiling on bacterial transcription has been further studied. In a promoter that is induced by DNA relaxation, the structure of the first transcribed region turns out to be important; when the DNA is supercoiled, many transcripts terminate prematurely, while full-length transcripts are formed on relaxed DNA. Experiments on the reverse DNA gyrase of thermophilic bacteria have shown that, unlike all other topoisomerases tested, this enzyme can only change supercoiling in one direction (toward positive supercoiling). Reverse gyrase is ATP-dependent, but can function with a remarkably low concentration of ATP.