RUI: Control of Proteasomal Unfolding Ability by Substrate Ubiquitination

蛋白酶体是真核细胞内的一台分子机器，它通过将不需要的或不需要的蛋白质拆开，将它们送入中央腔室，然后将它们切成小块，可以回收利用。要销毁的蛋白质被标记上了一条链，该链由一种名为泛素的小蛋白质的多个副本组成。在这个项目中，首席研究人员将与本科生和硕士学生一起，研究泛素链如何影响蛋白酶体解开附着的目标蛋白的能力。蛋白酶体在细胞功能的许多方面发挥着核心作用，因此更好地了解其机制，以及为什么一些蛋白质被降解而另一些蛋白质没有被降解，将有助于许多研究这些细胞过程的科学家。许多本科生和硕士生将致力于这个项目，并通过他们的智力投资，提高他们的批判性思维和科学探究技能，这将对他们在医学、工业、学术界或其他领域的职业生涯大有裨益。PI将与维拉诺瓦的学术进步计划合作，以激励代表不足的学生在大学期间进行研究。PI还将致力于为生物化学专业的学生传播一门以项目为基础的课程，让学生体验真正的研究。蛋白酶体是每个真核细胞中的一台大分子机器，它可以展开和降解注定要处理的蛋白质。因此，蛋白酶体通过控制细胞中数百种蛋白质的浓度来影响几乎所有的生物过程，因此是理解细胞生物学的基础。尽管蛋白酶体是中心性的，但关于蛋白酶体功能的问题仍然存在。在首席研究员实验室进行的这项研究的总体目标是了解蛋白酶体解开蛋白质的能力的分子决定因素。通常认为，如果一种蛋白质通过多泛素化作用被靶向蛋白酶体，那么该蛋白质就会被降解。然而，有时蛋白质被不完全降解，导致蛋白质片段具有新的甚至有毒的功能。不完全退化是何时或为什么发生的，目前还不完全清楚。在NSF资助的早期研究中，PI表明连接到底物蛋白上的多泛素链增加了蛋白酶体解开底物蛋白的能力，蛋白酶体泛素受体介导了这种激活。然而，其机制仍不清楚。在这个项目中，PI将决定(1)泛素链结构如何影响蛋白酶体展开底物的能力，(2)蛋白酶体相关蛋白如何与泛素受体结合影响蛋白酶体的展开能力，以及(3)如何与泛素受体结合传递给蛋白酶体马达蛋白。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The proteasome is a molecular machine inside eukaryotic cells that removes unwanted or unneeded proteins by unfolding them, feeding them into a central chamber, and then chopping them up into small pieces that can be recycled. Proteins destined for destruction are tagged with a chain composed of multiple copies of a small protein called ubiquitin. In this project, the principal investigator, together with undergraduate and master's students, will investigate how ubiquitin chains affect the ability of the proteasome to unfold the attached target protein. The proteasome is a central player in many aspects of cellular function, so better understanding of its mechanism, and why some proteins are degraded and others are spared, will benefit many scientists who study these cellular processes. Many undergraduate and master's students will work on this project, and, through their intellectual investment, will increase their critical thinking and scientific inquiry skills, which will serve them well as they go on to careers in medicine, industry, academia or other fields. The PI will work with Villanova's Academic Advancement program to excite underrepresented students about doing research while in college. The PI will also work to disseminate a project-based course for biochemistry majors that gives students a taste of real research.The proteasome is a macromolecular machine inside every eukaryotic cell that unfolds and degrades proteins destined for disposition. The proteasome therefore, impacts nearly all biological processes by controlling the concentration of hundreds of proteins in a cell, and so is foundational to understanding cellular biology. Despite the proteasome’s centrality, questions remain concerning proteasome function. The overall goal of the research conducted in the principal investigator's laboratory is to understand the molecular determinants of the proteasome's ability to unfold proteins. It is generally thought that if a protein is targeted to the proteasome via polyubiquitination, that protein is degraded. However, sometimes proteins are incompletely degraded, leading to protein fragments with new or even toxic functions. It is not fully understood when or why incomplete degradation occurs. In earlier NSF-funded research, the PI showed that the polyubiquitin chain attached to a substrate protein increases the ability of the proteasome to unfold the substrate protein and that proteasomal ubiquitin receptors mediate this activation. However, the mechanism remains unknown. In this project, the PI will determine (1) how the ubiquitin chain architecture affects the proteasome's ability to unfold a substrate, (2) how proteasome-associated proteins, in combination with ubiquitin receptors, influence the proteasome's unfolding ability and (3) how binding to ubiquitin receptors is communicated to the proteasomal motor proteins.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.