biostudies-literatureZerbes RMDeutsche Forschungsgemeinschaft (DFG)Excellence Initiative of the German Federal and State GovernmentsEuropean Research CouncilDeutsche Forschungsgemeinschaft353-384https://www.ebi.ac.uk/biostudies/studies/S-EPMC11772845biostudies-literatureUnknown26(2)The boundary and cristae domains of the mitochondrial inner membrane are connected by crista junctions. Most cristae membrane proteins are nuclear-encoded and inserted by the mitochondrial protein import machinery into the inner boundary membrane. Thus, they must overcome the diffusion barrier imposed by crista junctions to reach their final location. Here, we show that respiratory chain complexes and assembly intermediates are physically connected to the mitochondrial contact site and cristae organizing system (MICOS) that is essential for the formation and stability of crista junctions. We identify the inner membrane protein Mar26 (Fmp10) as a determinant in the biogenesis of the cytochrome bc₁ complex (complex III). Mar26 couples a Rieske Fe/S protein-containing assembly inteEMBO reportsCoordination of cytochrome bc<sub>1</sub> complex assembly at MICOS.PMC11772845CIBSS - EXC-2189 - project ID 390939984Consolidator Grant 648235BIOSS - EXC-294SFB 894 - project ID 157660137648235FOR 2848 - project ID 401510699SFB 746 - project ID 26068018van der Laan MKlar RFURampelt HPerschil IBohnert MOeljeklaus Sde Boer RPeikert CDvon der Malsburg KMehnert CSZerbes RMKram Avan der Klei IWarscheid BColina-Tenorio LfalseCoordination of cytochrome bc<sub>1</sub> complex assembly at MICOS.The boundary and cristae domains of the mitochondrial inner membrane are connected by crista junctions. Most cristae membrane proteins are nuclear-encoded and inserted by the mitochondrial protein import machinery into the inner boundary membrane. Thus, they must overcome the diffusion barrier imposed by crista junctions to reach their final location. Here, we show that respiratory chain complexes and assembly intermediates are physically connected to the mitochondrial contact site and cristae organizing system (MICOS) that is essential for the formation and stability of crista junctions. We identify the inner membrane protein Mar26 (Fmp10) as a determinant in the biogenesis of the cytochrome bc₁ complex (complex III). Mar26 couples a Rieske Fe/S protein-containing assembly inte2025-01-01T00:00:00Z2025 Jan2025-04-04T23:11:14.9Z2025-04-04T23:11:14.9ZS-EPMC117728453962316610.1038/s44319-024-00336-x