Protein Unfolding by Prokaryotic Energy Dependent Proteases

蛋白质链折叠成特定的三维形状是发挥其生物学功能所必需的。然而，在细胞中有一些关键的过程，蛋白质必须重新展开，例如当受损或调节蛋白被称为ATP依赖的蛋白酶的酶去除时。不能去除调节蛋白可能会导致细胞过程失灵，通常会导致细胞死亡。该项目研究依赖于ATP的蛋白水解酶如何展开和降解蛋白质。依赖于ATP的蛋白水解酶代表了一种新的、令人兴奋的分子机器。它们之所以有趣，是因为它们在细胞调控中发挥着核心作用，也因为它们催化了一个具有新颖机制特征的复杂过程。一些依赖于ATP的蛋白酶通过顺序地从降解标签上解开它们的底物来降解蛋白质。蛋白水解酶在其表面机械地展开蛋白质，然后将多肽链转移到蛋白质分解的活性部位。这些蛋白水解酶似乎会拉动底物的多肽链。对这一机制的新方面进行了研究。至少有四类依赖于ATP的蛋白酶存在。比较了它们的性质和机制，并分析了不同去折叠活性的生物学后果。通过拉动来展开的机制并不局限于蛋白酶，而是可以在其他生物机器的作用中找到，特别是蛋白质转位酶。因此，了解蛋白质通过拉力展开的机制具有广泛的生物学意义和意义。更广泛的影响：传播知识和教学也是该项目的重要方面。文理学院和工程学院的本科生以及当地高中的学生都参与了这个项目。该项目还将涉及与当地一所小学(K-8)进行外联。

Folding of protein chains into specific three-dimensional shapes is essential for performing their biological function. However, there are essential processes in the cell for which proteins must unfold again, such as when damaged or regulatory proteins are removed by enzymes called ATP-dependent proteases. Failure to remove regulatory proteins can lead to malfunctioning of cellular processes, often leading to cell death. This project investigates how ATP-dependent proteases unfold and degrade proteins. ATP-dependent proteases represent a new and exciting type of molecular machine. They are interesting because of the central role they play in cellular regulation and because they catalyze a complex process with novel mechanistic features. Some ATP-dependent proteases degrade proteins by sequentially unraveling their substrates from a degradation tag. The proteases mechanically unfold proteins at their surface and then translocate the polypeptide chain over a distance to the active sites of proteolysis. The proteases appear to pull at the substrates' polypeptide chains. New aspects of this mechanism are investigated. At least four classes of ATP-dependent proteases exist. Their properties and mechanisms are compared and the biological consequences of differences in the unfolding activity analyzed. The mechanism of unfolding by pulling is not restricted to proteases but can be found in the action of other biological machines, specifically protein translocases. Thus, understanding the mechanism of protein unfolding by pulling is of broad biological interest and significance. Broader Impacts: Dissemination of knowledge and teaching are also important aspects of this project. Undergraduates from the College of Arts and Sciences and the School of Engineering as well as students from local high schools are involved in the project. The project will also involve outreach to a local primary school (K-8).