INVESTIGATION INTO THE STRUCTURAL MECHANISM OF ALLOSTERIC MODULATION OF DNA CLEA

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 我们正在研究与其目标DNA结合的内切酶SgrAI的结构。核酸内切酶是DNA代谢的重要酶，参与DNA的复制、重组和修复等各个方面。SgrAI用于保护宿主免受噬菌体DNA的入侵，并在DNA上发生寡聚反应，导致激活的SgrAI酶被隔离。由寡聚引起的激活的SgrAI比未激活的形式切割初级位点DNA序列的速度快200倍，并且在次级位点DNA序列上的切割效率也更高。SgrAI的次级位点在宿主DNA中不受保护，SgrAI的切割会导致宿主基因组的损伤，从而对激活的SgrAI酶产生很强的选择压力。对SgrAI的齐聚界面、活化和非活化形式的三维结构进行了研究。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We are investigating the structure of an endonuclease, SgrAI, bound to its target DNA. Endonucleases are important enzymes involved in all aspects of DNA metabolism including replication, recombination, and repair. SgrAI serves to protect its host from invading phage DNA, and oligomerizes on DNA causing sequestration of the activated SgrAI enzyme. Activated SgrAI, caused by oligomerization, cleaves primary site DNA sequences 200 fold faster than the unactived form, and also cleaves more efficiently at secondary site DNA sequences. The secondary sites are not protected in the host DNA, and cleavage by SgrAI would result in genome damage to the host, resulting in strong selective pressure to sequestration of activated SgrAI enzymes. The oligomerization interfaces, and the structures of both activated and unactivated forms of SgrAI, are investigated for their three dimensional structures.