MODULATING THE REDUCTIVE UNFOLDING PATHWAY OF RNASE A

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（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。所列机构为中心，不一定是研究者所在机构。蛋白质的还原去折叠研究旨在提供有关intramol的信息。控制天然状态的形成（和稳定化）的相互作用以及关于折叠/解折叠途径。通过将模型蛋白中Tyr 92突变为G、A或L，牛胰腺RNA酶A，并通过温度分析，这些突变体的晶体结构的因素和分子动力学模拟，它表明，显着不同的还原展开速率和RNase A及其结构同源物onconase的途径可以归因于一个单一的，本地化的，环堆积之间的相互作用Tyr 92和Pro 93牛的变体。这种特殊的稳定相互作用的偶然位置在二硫键，contg。RNA酶A的环区导致蛋白质动力学的局部调节，这反过来又增强了二硫键对redn的敏感性。导致同源物的还原解折叠行为的改变。这些结果具有重要的意义，涉及拓扑的折叠研究。决定子以获得折叠/解折叠速率和途径，用于通过折叠识别预测蛋白质结构-功能，以及用于预测蛋白水解切割位点。三个结构存放在PDB（1 YMR，1 YMW和1 YMN），工作发表在JACS上。

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. Reductive unfolding studies of proteins are designed to provide information about intramol. interactions that govern the formation (and stabilization) of the native state and about folding/unfolding pathways. By mutating Tyr92 to G, A, or L in the model protein, bovine pancreatic RNase A, and through analysis of temp. factors and molecular dynamics simulations of the crystal structures of these mutants, it is demonstrated that the markedly different reductive unfolding rates and pathways of RNase A and its structural homolog onconase can be attributed to a single, localized, ring-stacking interaction between Tyr92 and Pro93 in the bovine variant. The fortuitous location of this specific stabilizing interaction in a disulfide-bond-contg. loop region of RNase A results in the localized modulation of protein dynamics that, in turn, enhances the susceptibility of the disulfide bond to redn. leading to an alteration in the reductive unfolding behavior of the homologues. These results have important implications for folding studies involving topol. determinants to obtain folding/unfolding rates and pathways, for protein structure-function prediction through fold recognition, and for predicting proteolytic cleavage sites. Three structures were deposited in the PDB (1YMR, 1YMW, and 1YMN) and the work was published in JACS.