Mechanisms of Cell Regulation and Manipulation by the Ubiquitin System

真核细胞具有高度保守的用于连接泛素（Ub）和相关蛋白的酶系统。 蛋白质，如SUMO蛋白质。这些修饰可能导致靶向药物的降解。 蛋白质，通常由蛋白酶体，但有时也由溶酶体。Ub和SUMO 修饰是高度动态的，这是由于去除它们的专门蛋白酶。两种修饰语 有许多关键作用，包括对人类生物学的重要贡献。基材包括 天然短寿命调节剂和异常的“蛋白质质量控制”（PQC）底物。许多 人类疾病，包括神经变性疾病、糖尿病和不同的癌症， 与Ub系统异常有关。该系统提供了许多潜在的目标， 药物开发针对一系列疾病。 在本申请中，PI建议对几种新发现的监管机构进行研究。 机制，这要么改变蛋白质修饰的Ub或反应的动态变化， 相扑运动以惊人的方式改变。一个焦点是酿酒酵母的反应 细胞失去了一种叫做Ulp 2的关键SUMO蛋白酶。这些细胞很快就会产生一种特殊的两种- 染色体非整倍性，但这最终是通过体外进化数百 世代相传进化轨迹是相关的，但不同的， 技术将其转化为一种强有力的方法来研究生理机制， 即使没有一种看似至关重要的酶也能适应并繁荣。 另一个新的研究方向解决了一个重要的酵母蛋白质的调节蛋白水解 控制蛋白酶体向细胞核的转移和核糖体的PQC。其 降解与其功能状态密切相关。蛋白酶体的亚细胞运动和 还将研究它们在饥饿条件下的降解情况。最后一个也是新的领域 解决了感染人类和其他人的内共生细菌的Ub系统酶 物种一个焦点是来自东方体的去泛素化酶（DUB）， 丛林斑疹伤寒是一种高致命性疾病令人惊讶的是，DUB蛋白不仅切割Ub， 紧密结合，以及网格蛋白衔接蛋白，小GTP酶，和一个特定的 磷脂在这个单一的多肽中的许多活动被认为是协调的， 有利于病原体感染和繁殖的方式。另一个引起极大兴趣的DUB来自 沃尔巴克氏体，感染数百万节肢动物物种的细菌，并利用这种不寻常的DUB改变 宿主繁殖并促进自身遗传。沃尔巴克氏体被用作 用于对抗疾病媒介，如传播登革热或疟疾的蚊子。

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.