Investigation of Two New Protein Post-Translational Modifications Derived from a Key Metabolite in Valine Metabolism

在化学系生命过程化学(CLP)项目的支持下，佐治亚大学的Y.George Zeng教授正在研究通过蛋白质翻译后修饰来调节生命过程的新的分子机制。蛋白质中特定的化学修饰可以影响受影响蛋白质的关键属性和功能，如结构构象、酶活性、细胞内定位以及与其他生物分子的相互作用。细胞和生物体通过微调的翻译后修饰来调整和调节自己的生理状态，以响应各种内部和外部刺激。目前，许多翻译后修饰的分子机制及其在调节生物过程中的作用尚不完全清楚。这也突出了另一个关键点，即可能有大量的翻译后修改(PTM)尚未确定。该项目致力于推动生物学研究领域的发展，识别尚未被发现的翻译后修饰，并阐明其中几个PTM调控关键生命过程的机制，如DNA转录、细胞周期控制和信号转导。将探索和应用化学和生物科学中的多学科方法和工具来识别、验证和功能注释人类蛋白质组中的翻译后修饰。预计拟议工作将支持教育和多样性，符合首席调查员在对不同背景的研究生、本科生和高中生进行科学培训方面的既定记录。早期职业实习生将学习和应用化学生物学中最先进的方法来解决分子信号传递中的相关问题，从而使化学生物学科学界广泛受益。在这个项目中，重点将放在识别和验证人类蛋白质中两个新的翻译后修饰，它们来自Valine代谢途径中的关键代谢物。研究人员推测，在缬氨酸代谢中产生的反应性代谢物甲基丙烯酰辅酶A和/或其水解物甲基丙烯酸酯能够通过两种不同的生化机制修饰细胞蛋白质：特定赖氨酸残基的酰化(赖氨酸甲基丙烯基化)和特定半胱氨酸残基的烷基化(S-2-羧丙基化)。特制的化学探针将被开发用于特异性识别和标记蛋白质和多肽中的赖氨酸甲基丙烯基化和半胱氨酸S-2-羧丙基化分子修饰，然后应用于建立化学蛋白质组平台，在蛋白质组水平上绘制出甲基丙烯基化和S-2-羧丙基化的蛋白质底物。生物信息学将被用来描绘赖氨酸甲基丙烯基化和半胱氨酸S-2-羧丙基化在人类蛋白质组中的分布和范围。此外，还将进行细胞和生化实验，以研究这些蛋白质修饰的动态控制和下游影响。这项工作预计将扩大对Valine代谢物及其对蛋白质翻译后修饰的贡献的理解，并在更广泛的水平上，促进分子水平理解表达的人类蛋白质组以及PTMS在调节和信号传递中的作用的工具包。该奖项反映了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。

With the support of the Chemistry of Life Processes (CLP) Program in the Division of Chemistry, Prof Y. George Zheng of the University of Georgia is investigating new molecular mechanisms of life process regulation by novel post-translational modification of proteins. Specific chemical modifications in proteins can impact key attributes and functions of affected proteins, such as structural conformation, enzymatic activity, intracellular localization, and interaction with other biomolecules. Through fine-tuned post-translational modifications, cells and organisms adjust and regulate their physiological states in response to various internal and external stimuli. Currently, the molecular mechanisms of many post-translational modifications and their roles in regulating biological processes are incompletely understood. This also highlights another key point; namely that there are likely a good number of post-translational modifications (PTMs) yet to be characterized. This project endeavors to advance biological research field by identifying as yet unrecognized post-translational modifications and elucidating the mechanisms by which several of these PTMs regulate key life processes such as DNA transcription, cell cycle control, and signal transduction. Multidisciplinary methods and tools in the chemical and biological sciences will be explored and applied to identify, validate, and functionally annotate post-translational modifications in the human proteome. The proposed work is expected to support education and diversity, consistent with the the principal investigator’s established record in the scientific training of graduate, undergraduate and high school students from diverse backgrounds. Early career trainees will learn and apply state-of-the-art methods in chemical biology to address relevant questions in molecular signaling, thereby benefiting the chemical biology science community broadly.In this project, a particular focus will be placed on identifying and validating two new post-translational modifications in human proteins that are derived from the key metabolites in the valine metabolic pathway. The researchers hypothesize that the reactive metabolite, methacrylyl-CoA, and/or its hydrolyzed product methacrylate, produced in valine metabolism are capable of modifying cellular proteins through two different biochemical mechanisms: acylation of specific lysine residues (lysine methacrylylation) and alkylation of specific cysteine residues (S-2-carboxypropylation). Tailored chemical probes will be developed to specifically recognize and label lysine methacrylylation and cysteine S-2-carboxypropylation molecular modifications in proteins and peptides, and then be applied to set up chemoproteomic platforms to map out methacrylylated and S-2-carboxypropylated protein substrates at the proteomic level. Bioinformatics will be used to delineate the distribution and scope of lysine methacrylylation and cysteine S-2-carboxypropylation in the human proteome. Furthermore, cellular and biochemical experiments will be conducted to investigate dynamic controls and downstream effects of these protein modifications. This work is projected to expand understanding of valine metabolites and their contribution to protein posttranslational modification, and to a broader level, advance the tool kit for molecular-level understanding of the expressed human proteome and the role of PTMs in regulation and signaling.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.