MECHANISM AND KINETICS OF RNA FOLDING BY SAXS

这个子项目是许多研究子项目中的一个 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。 RNA通过折叠成特定的三维结构来执行许多生物学功能。 理解RNA如何折叠对于理解RNA-蛋白质复合物如核糖体的组装、RNA对基因表达的调控以及RNA传感器和“核糖开关”的工程设计至关重要。 在抗衡离子的存在下，RNA折叠成紧凑的中间体，其随后折叠成天然三级结构。理论表明，不同折叠机制之间的竞争将RNA群体沿沿着交替折叠途径划分，其中一些导致动力学捕获和错误折叠的中间体。 RNA折叠中的一些重要问题包括：（1）成核和折叠的动力学机制，（2）阳离子和RNA序列如何决定初始折叠转变的特异性，以及（3）未折叠RNA系综中结构的分布。 我们计划解决这些问题，使用时间分辨小角X射线散射（SAXS）的第一组核酶从细菌Azoarcus。 拟议的研究将提供深入了解RNA的三级结构的成核，并提供在未折叠和折叠RNA的静电相互作用的理论模型的实验测试。 这项工作将包括野生型和突变体的Azoarcus和比较更广泛的研究四膜虫内含子。

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. RNAs perform many biological functions by folding into specific three-dimensional structures. Understanding how RNAs fold is crucial for understanding the assembly of RNA-protein complexes such as the ribosome, the regulation of gene expression by RNA, and the engineering of RNA sensors and "riboswitches". In the presence of counterions, RNAs collapse into compact intermediates, which subsequently fold into the native tertiary structure. Theory suggests that competition between different collapse mechanisms partitions the RNA population along alternate folding pathways, some of which lead to kinetically trapped and misfolded intermediates. Some of the important questions in RNA folding include (1) the kinetic mechanism of nucleation and collapse, (2) how cations and RNA sequence determine the specificity of the initial collapse transition, and (3) the distribution of structures in the ensemble of unfolded RNA. We plan to address these questions using time resolved small angle X-ray scattering (SAXS) on a group I ribozyme from the bacterium Azoarcus. The proposed studies will provide insight into the nucleation of RNA tertiary structure and provide experimental tests of theoretical models of electrostatic interactions in unfolded and folded RNAs. The work will include both wild type and mutants of Azoarcus and comparison to the more widely studied Tetrahymena intron.