Protein Unfolding by Prokaryotic Energy Dependent Proteases

将蛋白质链折叠成特定的三维形状对于执行其生物功能至关重要。然而，在细胞中有必要的过程，蛋白质必须再次展开，例如当受损或调节蛋白质被称为ATP依赖性蛋白酶的酶去除时。未能去除调节蛋白可能导致细胞过程的故障，通常导致细胞死亡。 本项目研究ATP依赖性蛋白酶如何展开和降解蛋白质。ATP依赖性蛋白酶代表了一种新的和令人兴奋的分子机器类型。 它们之所以有趣，是因为它们在细胞调节中发挥着核心作用，并且因为它们催化具有新机制特征的复杂过程。 一些ATP依赖性蛋白酶通过从降解标签顺序地解开其底物来降解蛋白质。 蛋白酶在其表面机械地解折叠蛋白质，然后将多肽链转移一段距离至蛋白质水解的活性位点。 蛋白酶似乎会拉动底物的多肽链。 这种机制的新方面进行了研究。 至少存在四类ATP依赖性蛋白酶。 比较了它们的性质和机制，并分析了展开活性差异的生物学后果。 通过拉伸展开的机制并不限于蛋白酶，而是可以在其他生物机器的作用中找到，特别是蛋白质移位酶。 因此，了解蛋白质拉伸解折叠的机制具有广泛的生物学意义。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参与了该项目。 该项目还将涉及到当地一所小学（K-8）。

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).