Vps39 Interacts with Tom40 to Establish One of Two Functionally Distinct Vacuole-Mitochondria Contact Sites

Publication date: 4 June 2018
Source:Developmental Cell, Volume 45, Issue 5
Author(s): Ayelén González Montoro, Kathrin Auffarth, Carina Hönscher, Maria Bohnert, Thomas Becker, Bettina Warscheid, Fulvio Reggiori, Martin van der Laan, Florian Fröhlich, Christian Ungermann
The extensive subcellular network of membrane contact sites plays central roles in organelle biogenesis and communication, yet the precise contributions of the involved machineries remain largely enigmatic. The yeast vacuole forms a membrane contact site with mitochondria, called vacuolar and mitochondrial patch (vCLAMP). Formation of vCLAMPs involves the vacuolar Rab GTPase Ypt7 and the Ypt7-interacting Vps39 subunit of the HOPS tethering complex. Here, we uncover the general preprotein translocase of the outer membrane (TOM) subunit Tom40 as the direct binding partner of Vps39 on mitochondria. We identify Vps39 mutants defective in TOM binding, but functional for HOPS. Cells that cannot form vCLAMPs show reduced growth under stress conditions and impaired survival upon starvation. Unexpectedly, our mutant analysis revealed the existence of two functionally independent vacuole-mitochondria MCSs: one formed by the Ypt7-Vps39-Tom40 tether and a second one by Vps13-Mcp1, which is redundant with ER-mitochondrial contacts formed by ERMES.

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Teaser

González Montoro et al. show that the vacuole-mitochondria contact site (vCLAMP) is established by interaction of Vps39 with Tom40. Generation of mutants that specifically disrupt this contact revealed its necessity for cell physiology during starvation and show that there are two functionally independent types of vacuole-mitochondrial contact sites.


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