SOLUTION SMALL-ANGLE X-RAY SCATTERING OF A RNA HELICASE AND ITS COMPLEXES WITH

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 Dex(D/H)-box RNA解旋酶是一种多结构域蛋白质，在许多不同的环境中负责RNA结构的“陪伴”，被认为经历了实质性的构象变化，以催化依赖于ATP的靶RNA的去折叠/重折叠。利用一个与23S rRNA的特定片段高亲和力结合的三域解旋酶(即枯草芽孢杆菌的YxiN蛋白)，我们建议使用溶液小角x射线散射来描述该蛋白质在RNA结合和驱动解旋酶活性的ATPase循环中所经历的构象变化。全长YxiN及其亚片段已经表达和纯化，YxiN或紧密同源物的单个结构域的晶体结构已经解决或正在进行中。各个结构域的晶体结构将被纳入对全长蛋白质及其亚片段的溶液构象的建模中。预计在没有配体的情况下，YxiN将具有扩展的构象，单个结构域通过灵活的结构域间连接子连接；RNA和ATP可能会诱导结构域缩合成紧密的络合物。

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. DEx(D/H)-box RNA helicases, which are responsible for "chaperoning" RNA structure in many different contexts, are multi-domain proteins that are thought to undergo substantial conformational changes in order to catalyze ATP-dependent unfolding/refolding of target RNAs. Working with a three-domain helicase that binds specific fragments of 23S rRNA with high affinity (namely, the YxiN protein of Bacillus subtilis), we propose to use solution small angle x-ray scattering to delineate the conformational changes this protein undergoes in response to RNA binding and the ATPase cycle that drives the helicase activity. Both full-length YxiN and subfragments thereof have been expressed and purified, and crystallographic structures of individual domains of YxiN or close homologs are solved or in progress. Crystallographic structures of the individual domains will be incorporated into modeling the solution conformations of the full-length protein and subfragments thereof. It is anticipated that in absence of ligands, YxiN will have an extended conformation with individual domains connected with flexible inter-domain linkers; RNA and ATP are likely to induce condensation of the domains into compact complexes.