Enabling Global Analysis of Protein Citrullination via Biotin Thiol Tag-Assisted Mass Spectrometry

Citrullination is a key post-translational modification (PTM) that affects protein structures and functions. Although it has been linked to various biological processes and disease pathogenesis, the underlying mechanism remains poorly understood due to a lack of effective tools to enrich, detect, and localize this PTM. Herein, we report the design and development of a biotin thiol tag that enables derivatization, enrichment, and confident identification of citrullination via mass spectrometry. We perform global mapping of the citrullination proteome of mouse tissues. In total, we identify 691 citrullination sites from 432 proteins which represents the largest data set to date. We discover novel distribution and functions of this PTM. This study depicts a landscape of protein citrullination and lays the foundation for further deciphering their physiological and pathological roles.

瓜氨酸化（Citrullination）是一类关键的翻译后修饰（post-translational modification, PTM），可调控蛋白质的结构与功能。尽管该修饰已被证实与多种生物学过程及疾病发病机制相关，但由于缺乏可用于富集、检测及定位该类修饰的有效工具，其潜在分子机制仍有待深入阐释。本研究设计并开发了一种生物素巯基标签，可通过质谱法实现瓜氨酸化修饰的衍生化、富集与可靠鉴定。我们对小鼠组织的瓜氨酸化蛋白质组开展了全局图谱绘制，最终从432种蛋白质中鉴定出691个瓜氨酸化位点，这是目前已报道的规模最大的相关数据集。本研究揭示了该翻译后修饰的全新分布特征与功能，系统描绘了蛋白质瓜氨酸化的全景图谱，为进一步解析其生理及病理作用奠定了坚实基础。