COUNTERION DEPENDENT FOLDING OF RNA

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。对控制RNA组装到三维结构的基本原理的理解仍然缺失。这一问题的解决将提高对聚电解质的认识，是RNA设计和操作的必要条件，是制药工业和生物技术中强有力的候选物。我们使用小角x射线散射（SAXS）技术观察偶氮弧菌核酶的大小随Mg2+和温度的变化。我们的分析表明，两态转换可以用来模拟折叠过程。这种转变强烈依赖于温度，在12-38℃范围内，随着温度的降低，这种转变变得不那么合作。我们通过突变破坏偶氮菌的一个三级相互作用，研究了三级相互作用对崩溃转变的影响。我们的测量表明，三级相互作用在塌缩态的稳定中起着重要的作用。在突变样本中，崩溃转变的中点显著增加，转变变得不那么合作。崩溃状态不像野生型核酶那样紧凑。结果表明，在坍塌状态下确实形成了三级相互作用，并对坍塌状态的稳定起着积极的作用。在我们未来的实验中，我们将观察其他突变RNA分子的折叠行为，以测量崩塌转变中不同结构域之间相互作用的相关性。

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. An understanding of basic principles governing the RNA assembly in to three dimensional structures is still missing. Solving this problem will improve the knowledge on polyelectrolytes, and is a requisite for the design and manipulation of RNA, which is a strong candidate to be used in pharmaceutical industry and in biotechnology. We used the Small Angle X-Ray Scattering (SAXS) technique to observe the size of the Azoarcus Ribozyme as a function of Mg2+ and temperature. Our analysis has indicated that a two-state transition can be used to model the folding process. This transition was strongly temperature dependent and became less cooperative with decreasing temperature over the range of 12-38C. We studied the effect of tertiary interactions on the collapse transition by disrupting one of the tertiary interactions in Azoarcus through a mutation. Our measurements pointed that the tertiary interactions play an important role in the stabilization of the collapsed state. In the mutated sample, the midpoint of the collapse transition increased significantly and the transition became less cooperative. The collapsed state was not as compact as the wild type ribozyme. The results show that tertiary interactions do form in the collapsed state, and they play an active role in stabilizing the collapsed state. In our future experiments, we will observe the folding behavior of additional mutated RNA molecules, in order to measure the relevance of interactions between different domains in the collapse transition.