CRYSTALLOGRAPHIC STUDIES OF LARGE MACROMOLECULAR ASSEMBLIES

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 正在进行的项目包括参与基因表达所有步骤的大分子组装。第一类是复制DNA所涉及的复制体组分，包括复制DNA聚合酶III、DNAB解旋酶和启动酶。与夹子复合并结合到DNA底物上的夹子加载器的结构也是人们追求的。正在研究的第二个组件是核糖体，特别是50S核糖体亚单位，将被扩展到包括整个70年代处于蛋白质合成过程的不同状态的核糖体。用EF-Tu或EF-G或释放因子结晶70年代核糖体的尝试正在进行中。此外，关于翻译70年代核糖体通过转位蛋白分泌蛋白质的研究进展顺利。第三个与基因表达无关的组件是脂肪酸合成酶，它是一个相对分子质量为250万的组件，包含8种酶活性，其晶体在24ID时衍射率为3.8°。最后，参与转录的蛋白质的结构研究，包括T7RNA聚合酶、脱脂代谢基因激活蛋白和与启动子DNA结合的大肠杆菌RNA聚合酶全酶的起始中间复合体。这些都是为了理解转录起始及其在单体和多亚单位酶中的调节。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The projects being pursued include large macromolecular assemblies that are involved in all steps of gene expression. The first of these are components of the replisome involved in copying DNA, including the replicating DNA polymerase III, DnaB helicase and primase. Also being pursued is the structure of the clamp loader complexed with the clamp and bound to a DNA substrate. The second assembly under study is the ribosome, specifically the 50S ribosomal subunit, is to be extended to include the entire 70S ribosome in various states of the protein synthesis process. Attempts to crystallize the 70S ribosome with EF-Tu, or EF-G, or release factors are underway. Further, studies of the translating 70S ribosome in the process of secreting protein through a translocon are well along. A third assembly not related to gene expression is that of fatty acid synthase, a 2.5 million molecular weight assembly containing 8 enzyme activities, whose crystals diffract to 3.8 ¿ resolution at 24 ID. Finally, structural studies of proteins involved in transcription including initiation intermediate complexes of T7 RNA polymerase, apo-catabolite gene activator protein and E. coli RNA polymerase holoenzyme bound to a promoter DNA. These are being pursued to understand transcription initiation and its regulation in a monomeric and multisubunit enzyme.