DYNAMIC CHARACTERIZATION OF SUBSTRATE RECOGNITION IN RNASE Z

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 酶动力学在双分子功能中发挥着越来越重要的作用。虽然已经了解了很多关于运动在小底物的识别和释放中所起的作用，但对大底物的识别，特别是大底物与具有高度柔性区域的大蛋白质的结合知之甚少。一个这样的系统，将提供深入了解这一知之甚少的领域是核糖核酸酶Z（RNase Z）。RNA酶Z是一种65 kD的同源二聚体，负责转移RNA 3'端的核酸内切加工。RNase Z由两个结构域组成：中心结构域和臂突起。中心结构域与B类同源？-内酰胺酶，并负责裂解反应。大约40个氨基酸的臂突出被认为是底物识别所必需的。据推测，动力学的臂变得显着改变后，基板结合，并负责协调和激活的催化结构域。溶液相NMR光谱是研究RNase Z动力学的理想技术，因为它提供了热力学参数的位点特异性定量。这些研究不仅有助于阐明RNase Z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.