Merklinger Lisa, Bauer Johannes, Pedersen Per A, Damgaard Rune Busk, Morth J Preben
Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark.
Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership University of Oslo, Oslo, Norway.
Life Sci Alliance. 2022 Apr 22;5(8). doi: 10.26508/lsa.202101309. Print 2022 Aug.
Mitochondrial homeostasis is tightly controlled by ubiquitination. The mitochondrial integral membrane ubiquitin ligase MARCH5 is a crucial regulator of mitochondrial membrane fission, fusion, and disposal through mitophagy. In addition, the lipid composition of mitochondrial membranes can determine mitochondrial dynamics and organelle turnover. However, how lipids influence the ubiquitination processes that control mitochondrial homeostasis remains unknown. Here, we show that lipids common to the mitochondrial membranes interact with MARCH5 and affect its activity and stability depending on the lipid composition in vitro. As the only one of the tested lipids, cardiolipin binding to purified MARCH5 induces a significant decrease in thermal stability, whereas stabilisation increases the strongest in the presence of phosphatidic acid. Furthermore, we observe that the addition of lipids to purified MARCH5 alters the ubiquitination pattern. Specifically, cardiolipin enhances auto-ubiquitination of MARCH5. Our work shows that lipids can directly affect the activity of ubiquitin ligases and suggests that the lipid composition in mitochondrial membranes could control ubiquitination-dependent mechanisms that regulate the dynamics and turnover of mitochondria.
线粒体稳态受泛素化严格调控。线粒体整合膜泛素连接酶MARCH5是通过线粒体自噬调节线粒体膜裂变、融合及清除的关键调控因子。此外，线粒体膜的脂质组成可决定线粒体动力学及细胞器更新。然而，脂质如何影响控制线粒体稳态的泛素化过程仍不清楚。在此，我们表明线粒体膜常见脂质与MARCH5相互作用，并在体外根据脂质组成影响其活性和稳定性。作为唯一经测试的脂质，心磷脂与纯化的MARCH5结合会导致热稳定性显著降低，而在磷脂酸存在时稳定性增强最为明显。此外，我们观察到向纯化的MARCH5中添加脂质会改变泛素化模式。具体而言，心磷脂增强了MARCH5的自身泛素化。我们的研究表明脂质可直接影响泛素连接酶的活性，并提示线粒体膜中的脂质组成可能控制调节线粒体动力学和更新的泛素化依赖性机制。
