Mechanisms of Cell Regulation and Manipulation by the Ubiquitin System

真核细胞具有高度保守的连接泛素(Ub)及其相关的酶系统 蛋白质，如相扑到蛋白质。这些修改可能会导致目标的降级 蛋白质，通常由蛋白酶体产生，有时也由溶酶体产生。UB和相扑 修饰是高度动态的，因为特殊的蛋白水解酶可以去除它们。两个修改器 有许多重要的作用，包括对人类生物学的重要贡献。衬底包括 天然短暂的调节剂和异常的“蛋白质质量控制”(PQC)底物。许多 人类疾病，包括神经退行性疾病、糖尿病和不同的癌症， 与Ub系统中的异常有关。该系统提出了许多潜在的目标 针对一系列疾病的药物开发。 在这项申请中，PI建议对几个新发现的监管机构进行研究 机制，要么改变Ub对蛋白质的修饰，要么对Ub动力学的变化做出反应 以惊人的方式修改相扑。其中一个焦点是酿酒酵母的反应。 细胞失去了一种名为Ulp2的关键相扑蛋白酶。细胞很快就会产生一种特定的两种- 染色体非整倍体，但这最终通过数百人的体外进化得到解决 世世代代。进化轨迹是相关的，但又是截然不同的，而且是深度排序的 技术将其转化为研究细胞的生理机制的有效方法 即使没有看似关键的酶也能适应并茁壮成长。 另一个新的研究方向涉及一种重要酵母蛋白的调节蛋白分解 它既控制着蛋白酶体向细胞核的转位，也控制着核糖体的PQC。它的 退化与其功能状态密切相关。蛋白酶体的亚细胞运动和 还将检查它们在饥饿条件下的降解情况。一个最终的，也是新的领域 解决来自感染人类和其他人的内共生细菌的Ub系统酶 物种。其中一个焦点是来自东方体的一种脱泛素化酶(DUB)，它是引起 丛林斑疹伤寒，一种高度致命的疾病。令人惊讶的是，Dub蛋白不仅能切割Ub，还能 与其紧密结合以及与网状蛋白接头蛋白、小的GTP酶和一种特定的 磷脂。这一单一多肽中的许多活动被认为是在一个 有利于病原体感染和繁殖的方式。另一首令人感兴趣的配音来自 沃尔巴克氏菌，感染数百万种节肢动物的细菌，并利用这种不同寻常的复制来改变 寄主繁衍，促进自身传承。沃尔巴克氏杆菌正被部署为代理人 用于抗击传播登革热或疟疾的蚊子等病媒。

Eukaryotic cells have highly conserved enzymatic systems for ligating ubiquitin (Ub) and related proteins such as SUMO to proteins. The modifications may lead to degradation of the targeted protein, usually by the proteasome but sometimes also by the lysosome. Ub and SUMO modifications are highly dynamic due to specialized proteases that remove them. Both modifiers have many crucial roles, including important contributions to human biology. Substrates include naturally short-lived regulators and aberrant “protein quality control” (PQC) substrates. Many human disorders, including neurodegenerative diseases, diabetes, and different cancers, are associated with abnormalities in the Ub system. The system presents many potential targets for drug development against a range of diseases. In this application, the PI proposes to undertake studies on several newly discovered regulatory mechanisms, which either alter protein modification by Ub or react to changes in the dynamics of SUMO modification in striking ways. One focus is on the response of Saccharomyces cerevisiae cells to loss of a key SUMO protease called Ulp2. The cells very quickly generate a specific two- chromosome aneuploidy, but this is eventually resolved through in vitro evolution over hundreds of generations. The evolutionary trajectories are related but distinct, and deep sequencing technologies turn this into a powerful way to study the physiological mechanisms that allow cells to adapt and flourish even without a seemingly crucial enzyme. Another new research direction addresses the regulated proteolysis of an essential yeast protein that controls both proteasome translocation into the nucleus and PQC at the ribosome. Its degradation is tightly linked to its functional state. Subcellular movements of proteasomes and their degradation under starvation conditions will also be examined. A final, also new area addresses Ub system enzymes from endosymbiotic bacteria that infect humans and other species. One focus is on a deubiquitylating enzyme (DUB) from Orientia, the causative agent of scrub typhus, a highly lethal disease. Surprisingly, the DUB protein not only cleaves Ub but also binds tightly to it as well as to clathrin adaptor proteins, small GTPases, and a specific phospholipid. The many activities in this single polypeptide are proposed to be coordinated in a way that favors pathogen infection and propagation. Another DUB of great interest is from Wolbachia, bacteria that infect millions of arthropod species and exploit this unusual DUB to alter host reproduction and promote their own inheritance. Wolbachia are being deployed as agents for fighting disease vectors such as the mosquitoes that transmit dengue fever or malaria.