GROEL VARIANT

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 Rye实验室的总体研究目标是了解GroEL如何与其伴侣蛋白GroES一起利用ATP水解的能量来促进完全GroEL依赖性底物蛋白（所谓的“严格”底物）的蛋白质折叠。GroEL和GroES都是七重环状低聚物。GroEL在其开环之一上捕获折叠中间体，然后结合ATP和辅助伴侣蛋白GroES，导致底物蛋白包封在封闭的GroEL-GroES复合物内。GroES如何完成底物包封以及GroEL对驱动生产性折叠的底物蛋白质的确切作用仍然知之甚少。黑麦已经使用定点诱变、化学修饰和荧光光谱的组合来解决这些问题（Lin和Rye，2004; Lin等人，2008年）。 以前的研究无法捕获和研究GroEL-GroES复合物的预触发状态并不奇怪，因为野生型GroEL只能短暂地填充这种变构状态（大约100毫秒），对于准备操作来说时间太短。 相比之下，我们修改后的GroEL变体似乎以相当慢的速度通过这种转变。 我们建议，利用NCMI在通过冷冻EM检查GroEL等分子方面取得的技术进步，对这种新的GroEL变体进行高分辨率观察，可能会提供GroEL的关键变构状态的前所未有的快照GroEL-GroES机器，我们目前对此知之甚少。

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 overall research goal in Rye's lab is to understand how GroEL, in conjunction with its partner protein GroES, utilizes the energy of ATP hydrolysis to promote protein folding of fully GroEL-dependent substrate proteins (so-called "stringent" substrates). Both GroEL and GroES are seven-fold, ring shaped oligomers. GroEL captures a folding intermediate on one of its open rings, then binds ATP and the co-chaperonin GroES, resulting in the encapsulation of the substrate protein within an enclosed GroEL-GroES complex. How sub-strate encapsulation by GroES is accomplished and precisely what GroEL does to a substrate protein that drives productive folding remain poorly understood. Rye has approached these problems using a combination of site-directed mutagenesis, chemical modification and fluorescence spectroscopy (Lin and Rye, 2004; Lin et al., 2008). The inability of previous studies to trap and study a pre-triggered state of the GroEL-GroES complex is not surprising, given that wild-type GroEL populates this allosteric state only transiently (for a hundred millisec or so), much too short a time for ready manipulation. By contrast, our modified GroEL variant appears to move through this transition at a considerably slower rate. We propose that a high-resolution look at this new GroEL variant, exploiting the technical advances the NCMI has made in examining molecules like GroEL by cryo-EM, is likely to provide an unprecedented snap-shot of a critical allosteric state of the GroEL-GroES machine about which we currently know very little.