Mitochondrial dysfunction underlies the etiology of a broad spectrum of diseases including heart disease, cancer, neurodegenerative diseases, and the general aging process. Therapeutics that restore healthy mitochondrial function hold promise for treatment of these conditions. The synthetic tetrapeptide, elamipretide (SS-31), improves mitochondrial function, but mechanistic details of its pharmacological effects are unknown. Reportedly, SS-31 primarily interacts with the phospholipid cardiolipin in the inner mitochondrial membrane. Here we utilize chemical cross-linking with mass spectrometry to identify protein interactors of SS-31 in mitochondria. The SS-31-interacting proteins, all known cardiolipin binders, fall into two groups, those involved in ATP production through the oxidative phosphorylation pathway and those involved in 2-oxoglutarate metabolic processes. Residues cross-linked with SS-31 reveal binding regions that in many cases, are proximal to cardiolipin–protein interacting regions. These results offer a glimpse of the protein interaction landscape of SS-31 and provide mechanistic insight relevant to SS-31 mitochondrial therapy.

线粒体功能障碍是多种疾病的病因学基础，包括心脏病、癌症、神经退行性疾病和一般衰老过程。恢复健康线粒体功能的疗法有望治疗这些疾病。合成四肽埃拉米普肽 (SS-31) 可改善线粒体功能，但其药理作用的机制细节尚不清楚。据报道，SS-31 主要与线粒体内膜中的磷脂心磷脂相互作用。在这里，我们利用化学交联和质谱法来鉴定线粒体中 SS-31 的蛋白质相互作用因子。 SS-31 相互作用蛋白（所有已知的心磷脂结合物）分为两类：通过氧化磷酸化途径参与 ATP 生成的蛋白和参与 2-酮戊二酸代谢过程的蛋白。与 SS-31 交联的残基揭示了在许多情况下靠近心磷脂-蛋白质相互作用区域的结合区域。这些结果让我们一睹 SS-31 的蛋白质相互作用情况，并提供与 SS-31 线粒体治疗相关的机制见解。