STRUCTURAL BASIS OF RNA THERMOSTABILITY

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。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者的研究机构。 所有细菌RNase P RNA都由两个独立折叠的结构域组成。这些结构域在嗜热脂肪芽孢杆菌RNase P RNA的晶体结构中彼此堆积。这种并排的包装被广泛认为是细菌P RNA可以适应的唯一天然结构。在这里，我们使用小角度X射线散射，在线探测和分子模拟，从枯草芽孢杆菌的P RNA，一个密切的同系物的B。嗜热脂肪菌，根据单价阳离子的存在，采用两种完全不同的天然结构。在高离子条件下（e100 mM）的结构是20%更紧凑的催化和特异性结构域的相对取向的变化的结果。这种结构由晶体结构很好地表示。我们还生成了一个分子模型的结构在低离子条件下的结构，匹配的分子包络线从SAXS测量。晶体结构和模型与数据之间的协议使用互相关函数进行量化。我们的研究结果表明，多结构域RNA可以有一个以上的稳定的天然结构。在P RNA的情况下，这些结构可能在RNase P全酶（一种核糖核蛋白颗粒）的组装中很重要。

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. All bacterial RNase P RNAs are composed of two independently folding domains. These domains pack against each other in the crystal structure of the Bacillus stearothermophilus RNase P RNA. This side-by-side packing is widely assumed to be the only native structure bacterial P RNAs can adapt. Here we show using small-angle X-ray scattering, in-line probing and molecular modeling that the P RNA from Bacillus subtilis, a close homolog of B. stearothermophilus, adopts two globally distinct native structures depending on the presence of monovalent cations. The structure under high ionic conditions (e100 mM) is 20% more compact as a result of a change in the relative orientation of the catalytic and specificity domains. This structure is well represented by the crystal structure. We also generate a molecular model for the structure under low ionic conditions structures that matches the molecular envelop obtained from the SAXS measurements. The agreement between the crystal structure and the models with the data is quantified using a cross-correlation function. Our results indicate that multi-domain RNAs can have more than one stable native structure. In the case of P RNA, these structures may be important in the assembly of the RNase P holoenzyme, a ribonucleoprotein particle.