Novel Chemical Probes for Selective Tagging of Dimethyl Lysine Posttranslational Modifications and Mediated Protein Protein Interactions

在化学系生命过程化学（CLP）项目的支持下，埃默里大学的Monika Raj正在研究蛋白质中特定氨基酸的化学修饰如何影响它们在各种生物过程和疾病中的作用。对蛋白质中赖氨酸单位的修饰可以开启或关闭细胞内非常重要的功能，这些功能负责细胞生长和细胞间的交流。深入了解赖氨酸修饰及其对蛋白质之间相互作用的影响对于开发破坏蛋白质-蛋白质相互作用的新分子至关重要，并且有朝一日可能作为各种疾病的治疗方法。然而，确定有影响的赖氨酸修饰是一个特别艰巨的挑战，传统的生化策略尚未完全满足。Raj博士的目标是开发新的方法，使修饰赖氨酸单元的选择性化学标记和蛋白质伙伴的连接成为可能。这些创新的化学方法有望为系统地识别赖氨酸修饰和赖氨酸修饰引起的蛋白质-蛋白质相互作用提供一般策略。该项目的进一步影响是努力吸引不同年龄、教育水平、社会经济和文化背景的未被充分代表的个人，并鼓励他们对STEM（科学、技术、工程和数学）的积极兴趣和保留。这些努力的重点是将不同群体的研究生和本科生聚集在一起，以获得有机化学和生物化学的跨学科研究训练。与高中生（特别是女性和来自代表性不足群体的个人）的外展活动将通过有趣的实验让他们了解生物化学的基本概念，并旨在为他们提供必要的社会支持，以促进他们在大学里攻读STEM专业。在蛋白质表面存在活性氨基酸侧链的情况下，化学策略成功靶向单个氨基酸位点上的特定官能团是有限的。更罕见的是，有机反应可以在足够温和的条件下进行，以标记生物分子而不会产生有害影响。为了应对这些挑战，该研究项目将开发基于与亲核试剂的氧化偶联和亲核取代的化学探针，使光反应性和亲和性基团在修饰赖氨酸附近的位点特异性结合。该方法将用于位点选择性标记与各种货物的修饰赖氨酸和捕获由修饰赖氨酸单位介导的蛋白质-蛋白质相互作用。赖氨酸异常修饰蛋白质可以触发其与其他蛋白质的独特相互作用，从而导致各种不同的疾病；然而，选择性检测赖氨酸修饰和相关蛋白-蛋白相互作用的化学方法仍然缺乏。这项研究将提供高选择性的化学探针，可以有效地检测修饰的赖氨酸并捕获它们的蛋白质伴侣。因此，提出的研究有很大的潜力来进一步了解这些赖氨酸修饰及其畸变如何调节各种细胞信号传导过程并导致各种疾病。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemistry of Life Processes (CLP) Program in the Division of Chemistry, Monika Raj of Emory University is studying how chemical modification of specific amino acids in proteins influences their role in various biological processes and diseases. Modifications to lysine units in proteins are known to turn on or turn off very important functions inside cells, which are responsible for cell growth and communication between cells. A deep understanding of lysine modifications and their influence on interactions between proteins is crucial to the development of new molecules that disrupt those protein-protein interactions and may someday serve as therapeutics of various diseases. However, identifying influential lysine modifications is a particularly daunting challenge that has yet to be fully met by traditional biochemical strategies. Dr. Raj aims to develop new approaches that enable selective chemical labeling of modified lysine units and the linking of protein partners. These innovative chemical approaches are anticipated to provide a general strategy to systematically identify lysine modifications and protein-protein interactions caused by lysine modifications. Furthering impact of the project are efforts that engage underrepresented individuals across a range of ages, educational levels, and socioeconomic and cultural backgrounds, and encourage their active interest and retention in STEM (Science, Technology, Engineering and Mathematics). Those efforts focus on bringing together a diverse group of graduate and undergraduate students to gain interdisciplinary research training in organic chemistry and biochemistry. Outreach activities with high school students (especially women and individuals from underrepresented groups) will expose them to basic concepts of biochemistry through fun experimentation and aim to equip them with the social support needed to facilitate the pursuit of a STEM major in college. Chemical strategies successfully target a particular functional group at a single amino acid site in the presence of reactive amino acid side chains on protein surfaces are limited. Even more rare are organic reactions that can proceed under conditions mild enough to label biomolecules without deleterious effects. To address these challenges, this research project will develop chemical probes based on oxidative coupling with nucleophiles and nucleophilic substitutions that enable site-specific incorporation of photoreactive and affinity groups near modified lysines. This method will be employed for the site-selective labeling of modified lysine with various cargoes and for capturing protein-protein interactions mediated by modified lysine units. Abnormal lysine modification of a protein can trigger its unique interaction with other proteins, thus leading to a variety of different diseases; however, the chemical methods for selective detection of lysine modification and associated protein-protein interactions are still lacking. This research will provide highly selective chemical probes that can effectively detect modified lysine and capture their protein partners. Thus, the proposed research has a great potential to further our understanding of how these lysine modifications and their aberrations regulate various cellular signaling processes and lead to various diseases.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.