Vps39 interacts with Tom40 to establish one of two functionally distinct vacuole-mitochondria contact sites
González Montoro A, Auffarth K, Hönscher C, Bohnert M, Becker T, Warscheid B, Reggiori F, van der Laan M, Fröhlich F, Ungermann C.
Mitochondria form several molecular contact sites to other cellular membranes, including the endoplasmic reticulum and the vacuolar membrane. Such contact sites are pivotal to integrate mitochondria into the cellular environment for the exchange of lipids and small molecules. In yeast, the vacuolar mitochondrial patch (vCLAMP) forms a molecular tether between mitochondria and the vacuolar membrane. The Rab GTPase Ypt7 and Vps39 are components of vCLAMP. Vps39 is also part of the homotypic fusion and vacuolar tethering (HOPS) complex. However, the mitochondrial anchor remained unknown. Here, Tom40 was identified as binding partner of Vps39. Tom40 is the protein-conducting channel of the translocase of the outer mitochondrial membrane (TOM complex). Cells defective in the formation of vCLAMP show an impaired growth under stress conditions and starvation. In addition, Vps13 and the mitochondrial Mcp1 form a second tether between mitochondria and the vacuolar membrane. Thus, mitochondria and the vacuole are connected via two molecular tethers. The central subunit of the TOM complex, Tom40, is involved in tether the vacuolar membrane to mitochondria, providing an exciting link between protein biogenesis and organelle contact sites.
