Funding Organization(s): The Swedish Foundation for Strategic Research, Cancerfonden, European Research Council (ERC), Knut and Alice Wallenberg Foundation
Mitochondrial energy conversion requires an intricate architecture of the inner mitochondrial membrane 1 . Here we show that a supercomplex containing all four respiratory chain components contributes to membrane curvature induction in ciliates. We report cryo-electron microscopy and cryo-tomography structures of the supercomplex that comprises 150 different proteins and 311 bound lipids, forming a stable 5.8-MDa assembly. Owing to subunit acquisition and extension, complex I associates with a complex IV dimer, generating a wedge-shaped gap that serves as a binding site for complex II. Together with a tilted complex III dimer association, it results in a curved membrane region. Using molecular dynamics simulations, we demonstrate that the divergent supercomplex actively contributes to the membrane curvature induction and tubulation of cristae. Our findings highlight how the evolution of protein subunits of respiratory complexes has led to the I-II-III 2 -IV 2 supercomplex that contributes to the shaping of the bioenergetic membrane, thereby enabling its functional specialization.
Organizational Affiliation:
Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.
School of Infection and Immunity, University of Glasgow, Wellcome Centre for Integrative Parasitology, Glasgow, UK.
Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark.
MRC Laboratory of Molecular Biology, Cambridge, UK.
Department of Physics, University of Helsinki, Helsinki, Finland.
Institute of Structural and Molecular Biology, Birkbeck College, London, UK.
National Center for Biotechnology Information, National Library of Medicine, National Institute of Health, Bethesda, MD, USA.
Institute of Structural and Molecular Biology, University College London, London, UK.
HiLIFE Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden. amunts@scilifelab.se.
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