RNA POLYMERASE SUBUNITS ALPHACTD AND SIGMA REGION4 IN COMPLEX WITH DNA

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 DNA转录成RNA是蛋白质合成所需信息传递的中心过程。原核生物转录的研究为理解所有生命系统中的转录事件提供了一个简单的模型。这项工作的目标是表征参与转录起始在I类分解代谢物激活蛋白（CAP）依赖的启动子在细菌中的结构因子。为此，含有CAP，DNA和RNA聚合酶（<$$>-CTD）的<$$>亚基的C-末端结构域的晶体结构，这是最近在本实验室解决的，扩展到包括<$<$？RNA聚合酶亚基（？第四区还是？R4）。那个？RNA聚合酶的R4被认为在转录起始时与-CTD和DNA特异性接触。因此，CAP、DNA、CTD和？R4已经结晶。数据已在NSLS X25至3.5上收集？我们现在有晶体，我们相信它由CASD复合物与alphaCTD、sigma区域4和DNA（ASD）的子组装体组成。 在康奈尔同步加速器收集的几个测试图像表明衍射超过3 A，晶格尺寸与建议的内容一致。 如果这些晶体确实是ASD复合物，确定这种结构将为完成NIH资助项目的几个具体目标提供非常令人满意的手段。

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. The transcription of DNA into RNA is a central process in the transfer of information required for protein synthesis. The study of transcription in prokaryotes provides a simple model for understanding transcription events in all living systems. The goal of this work is to characterize the structural factors involved in transcription initiation at Class I catabolite activator protein (CAP)-dependent promoters in bacteria. To this end, a crystal structure containing CAP, DNA and the C-Terminal Domain of the ¿¿ subunit of RNA polymerase (¿¿-CTD), which has been recently solved in this lab, is expanded to include the C-terminus of the ¿? subunit of RNA polymerase (¿? Region 4 or ¿?-R4). The ¿?-R4 of RNA polymerase is thought to make specific contacts with ¿¿-CTD and DNA in transcription initiation. Thus, a complex of CAP, DNA, ¿¿-CTD, and ¿?-R4 has been crystallized. Data has been collected on NSLS X25 to 3.5 ¿? resolution, but we have not yet been able to complete structure determination.We now have crystals that we believe consist of a subassembly of the CASD complex with alphaCTD, sigma region 4, and DNA (ASD). Several test images collected at the Cornell synchrotron indicate diffraction beyond 3 A, and lattice dimensions consistent with the proposed contents. If these crystals are indeed an ASD complex, determining this structure will be provide a very satisfactory means to complete several of the specific aims of this NIH-funded project.