Structures of respiratory supercomplexes and ATP synthase oligomers in mammalian mitochondrial inner membrane.
basic_science · Level V
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- Record sourced from PubMed, PMID 41844608.
- Also identified by DOI 10.1038/s41467-026-70578-x.
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Abstract
Understanding the functional mechanisms of membrane protein complexes requires structural analysis within their native membrane environment. Here, we applied cryo-electron microscopy to determine the structures of F<sub>o</sub>F<sub>1</sub> ATP synthase and respiratory supercomplexes (SCs) on sub-mitochondrial particles (SMPs) isolated from bovine heart mitochondria. Most F<sub>o</sub>F<sub>1</sub> complexes were observed as dimers stabilized by the regulatory factor IF₁, and a tetrameric assembly comprising two F<sub>o</sub>F<sub>1</sub>-IF₁ dimers arranged linearly was also identified. This finding indicates that the tetrameric units of F<sub>o</sub>F<sub>1</sub> are present in the mitochondrial inner membrane and contribute to shaping cristae tips in mammalian mitochondria. F<sub>o</sub> domain maps resolve the e-subunit- c₈-ring interface and show no discrete density for a tightly bound lipid within the c₈-ring. In addition to the previously reported SCs compositions CI₁CIII₂CIV₁ and CI₁CIII₂CIV₂, our analysis identified an additional assembly with the composition CI₁CIII₂CIV₃, as well as a CI₂CIII₂CIV₆ mega-complex. This approach enables rapid structural determination of F<sub>o</sub>F<sub>1</sub> ATP synthase and SCs from minimal membrane fractions, providing a foundation for elucidating the molecular basis of metabolic disorders and mitochondrial diseases at the level of higher-order architecture.