DYNAMIC CHARACTERIZATION OF SUBSTRATE RECOGNITION IN RNASE Z

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。 酶动力学在双分子功能中发挥着越来越重要的作用。虽然关于运动在识别和释放小底物中所起的作用已经了解很多，但对于大底物的识别，特别是大底物与具有高度灵活区域的大蛋白的结合，人们了解的很少。一个这样的系统将提供对这个鲜为人知的领域的洞察是核糖核酸酶Z(RNaseZ)。RNaseZ是一个65kD的同源二聚体，负责转移RNA 3‘端的内切加工。RNaseZ由两个结构域组成：中心结构域和手臂突起。中心结构域与B类β-内酰胺酶同源，负责切割反应。大约40个氨基酸的手臂突出被认为是底物识别所必需的。假设手臂的动力学在底物结合时会发生显着变化，并负责催化结构域的协调和激活。溶液相核磁共振波谱是研究RNaseZ动力学的理想技术，因为它提供了特定位置的热力学参数的定量。这些研究不仅有助于阐明RNaseZ鲜为人知的机制，而且有助于进一步了解蛋白质运动及其在生物功能中的作用。

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. Enzyme dynamics are being revealed to play an increasingly important role in bimolecular function. While much has been learned about the role motions play in the recognition and release of small substrates, little is understood about the recognition of large substrates and, in particular, the binding of large substrates to large proteins with highly flexible regions. One such system that will provide insight into this poorly understood area is ribonuclease Z (RNase Z). RNase Z is a 65 kD homodimer responsible for the endonucleolytic processing of the 3' end of transfer RNAs. RNase Z is comprised of two domains: a central domain and an arm protrusion. The central domain is homologus to class B ?-lactamases and is responsible for the cleavage reaction. The arm protrusion of approximately 40 amino acids is believed to be essential for substrate recognition. It is hypothesized that dynamics of the arm become dramatically altered upon substrate binding and are responsible for the coordination and activation of the catalytic domain. Solution phase NMR spectroscopy is the ideal technique to study the dynamics of RNase Z as it affords site-specific quantification of thermodynamic parameters. These studies will not only help elucidate the poorly understood mechanism of RNase Z, but also to further understanding of protein motions and their role in biological function.