RT Journal Article SR Electronic T1 Phospholipids alter activity and stability of mitochondrial membrane-bound ubiquitin ligase MARCH5 JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202101309 DO 10.26508/lsa.202101309 VO 5 IS 8 A1 Merklinger, Lisa A1 Bauer, Johannes A1 Pedersen, Per A A1 Damgaard, Rune Busk A1 Morth, J Preben YR 2022 UL http://www.life-science-alliance.org/content/5/8/e202101309.abstract AB 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.