CHAPERONE-MEDIATED FOLDING OF A GROUP I INTRON RNA MONITORED BY SAXS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 许多功能RNA在反离子存在的情况下折叠为离散的天然结构。这是关键的一步 折叠过程是一种全局压实过程，已经成功地用小角X射线散射(SAXS)对几个RNA(1-6)进行了监测。对于研究得很好的四膜虫I组核酶，这一整体压实过程的时间常数为~100ms，而完全折叠到自然状态的速度要慢几个数量级，这是因为至少形成了两个错误折叠的构象(3，7，8)。细胞色素T-19是一种死盒ATPase蛋白，在体内参与I组内含子和其他RNA的折叠。我们最近使用核酶活性作为自然折叠的读数，以表明Cyt-19通过非特异性地促进部分展开来加速这些错误折叠的中间产物之一的折叠(9，10)。这种非特定的展开允许更稳定的自然结构积累。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Many functional RNAs fold in the presence of counterions to discrete native structures. A crucial step in this folding process is a global compaction, which has been monitored successfully by small angle x-ray scattering (SAXS) for several RNAs (1-6). For the well-studied Tetrahymena group I ribozyme, this global compaction process occurs with a time constant of ~100 ms, whereas complete folding to the native state is slower by several orders of magnitude due to the formation of at least two misfolded conformations (3, 7, 8). CYT-19 is a DEAD-box ATPase protein that functions in vivo in folding of group I introns and other RNAs. We have recently used ribozyme activity as a readout for native folding to show that CYT-19 accelerates folding from one of these misfolded intermediates by non-specifically promoting partial unfolding (9, 10). This non-specific unfolding allows the more stable native structure to accumulate.