Covalent modulators and covalent degrader molecules have emerged as drug modalities with tremendous therapeutic potential. Toward realizing this potential, mass spectrometry-based chemoproteomic screens have generated proteome-wide maps of potential druggable cysteine residues. However, beyond these direct cysteine-target maps, the full scope of direct and indirect activities of these molecules on cellular processes and how such activities contribute to reported modes of action, such as degrader activity, remains to be fully understood. Using chemoproteomics, we identified a cysteine-reactive small molecule degrader of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nonstructural protein 14 (nsp14), which effects degradation through direct modification of cysteines in both nsp14 and in host protein disulfide isomerases. This degrader activity was further potentiated by generalized electrophile-induced global protein ubiquitylation, proteasome activation and widespread aggregation and depletion of host proteins, including the formation of stress granules. Collectively, we delineate the wide-ranging impacts of cysteine-reactive electrophilic compounds on cellular proteostasis processes.

共价调节剂和共价降解剂分子已成为具有巨大治疗潜力的药物形式。为了实现这一潜力，基于质谱的化学组学筛选已经生成了潜在可成药半胱氨酸残基的蛋白质组范围图谱。然而，除了这些直接的半胱氨酸靶标图谱之外，这些分子对细胞过程的全部直接和间接活性以及这些活性如何促进已报道的作用模式（如降解剂活性）仍有待完全了解。使用化学蛋白质组学，我们鉴定了严重急性呼吸系统综合症冠状病毒 2 （SARS-CoV-2） 非结构蛋白 14 （nsp14） 的半胱氨酸反应性小分子降解剂，它通过直接修饰 nsp14 和宿主蛋白二硫键异构酶中的半胱氨酸来影响降解。这种降解剂活性通过广义亲电试剂诱导的全局蛋白质泛素化、蛋白酶体激活以及宿主蛋白的广泛聚集和耗竭（包括应激颗粒的形成）进一步增强。总的来说，我们描述了半胱氨酸反应性亲电化合物对细胞蛋白质稳态过程的广泛影响。