The SPFH (stomatin, prohibitin, flotillin, HflC/K) superfamily is composed of scaffold proteins that form ring‐like structures and locally specify the protein–lipid composition in a variety of cellular membranes. Stomatin‐like protein 2 (SLP2) is a member of this superfamily that localizes to the mitochondrial inner membrane (IM) where it acts as a membrane organizer. Here, we report that SLP2 anchors a large protease complex composed of the rhomboid protease PARL and the i‐AAA protease YME1L, which we term the SPY complex (for SLP2–PARL–YME1L). Association with SLP2 in the SPY complex regulates PARL‐mediated processing of PTEN‐induced kinase PINK1 and the phosphatase PGAM5 in mitochondria. Moreover, SLP2 inhibits the stress‐activated peptidase OMA1, which can bind to SLP2 and cleaves PGAM5 in depolarized mitochondria. SLP2 restricts OMA1‐mediated processing of the dynamin‐like GTPase OPA1 allowing stress‐induced mitochondrial hyperfusion under starvation conditions. Together, our results reveal an important role of SLP2 membrane scaffolds for the spatial organization of IM proteases regulating mitochondrial dynamics, quality control, and cell survival.
The membrane scaffold SLP2 anchors a large protease complex containing the rhomboid protease PARL and the i‐AAA protease YME1L in the inner membrane of mitochondria, termed the SPY complex. Assembly into the SPY complex modulates PARL activity toward its substrate proteins PINK1 and PGAM5.
SLP2 assembles with PARL and YME1L into the SPY complex in the mitochondrial inner membrane.
Assembly into SPY complexes modulates PARL‐mediated processing of PINK1 and PGAM5.
SLP2 restricts OMA1‐mediated processing of the OPA1.
EMBO Reports (2016) 17: 1844–1856
- Received May 9, 2016.
- Revision received September 13, 2016.
- Accepted September 15, 2016.
- © 2016 The Authors