bims-resufa Biomed News
on Respiratory supercomplex factors
Issue of 2025–05–11
two papers selected by
Gavin McStay, Liverpool John Moores University
  1. The association of mitochondrial morphology and supercomplex redistribution with skeletal muscle oxidative capacity in older adults.
  2. Cryo-EM of Mitochondrial Complex I and ATP Synthase.
  1. Physiol Rep. 2025 May;13(9): e70359
    The association of mitochondrial morphology and supercomplex redistribution with skeletal muscle oxidative capacity in older adults.
    Mauricio Castro Sepulveda, Sylviane Lagarrigue, Francesca Amati.
      Skeletal muscle maximal oxidative capacity (ATPmax) is a key component of age-related sarcopenia and muscle health. The contribution of mitochondrial morphology and electron transport chain supercomplex (SC) assemblies to ATPmax has yet to be determined in human muscle. ATPmax measured in vivo by 31phosphorus magnetic resonance spectroscopy in the quadriceps femoris of nine volunteers (65.5 ± 3.3 years old) was correlated with muscle biopsy outcomes before and after 4 months of supervised exercise. Mitochondrial morphology was assessed in electron micrographs, and SCs were measured by blue native gel electrophoresis. In the sedentary conditions, ATPmax was positively associated with complex (C) I and CIII in SC I+III2+IVn and negatively associated with CI and CIII in SC I+III2. Regarding mitochondrial morphology, ATPmax was positively associated with markers of mitochondrial elongation. Exercise training-induced increases in ATPmax were accompanied by mitochondrial elongation and by the redistribution of free complex III. Indicators of mitochondrial elongation were associated with the redistribution of specific complexes to SC I+III2+IVn. Higher skeletal muscle oxidative capacity in older adults is associated with mitochondrial elongation and the redistribution of electron transport chain complexes into higher rank SCs in the same muscle. Further, we provide evidence that mitochondrial elongation favors mitochondrial SC assembly.
    Keywords:  ATPmax; electron transport chain; mitochondrial elongation; respirasome
    DOI:  https://doi.org/10.14814/phy2.70359
  2. Annu Rev Biophys. 2025 May;54(1): 209-226
    Cryo-EM of Mitochondrial Complex I and ATP Synthase.
    Werner Kühlbrandt, Luis A M Carreira, Özkan Yildiz.
      Cryo-electron microscopy (cryo-EM) is the method of choice for investigating the structures of membrane protein complexes at high resolution under near-native conditions. This review focuses on recent cryo-EM work on mitochondrial complex I and ATP synthase. Single-particle cryo-EM structures of complex I from mammals, plants, and fungi extending to a resolution of 2 Å show different functional states, indicating consistent conformational changes of loops near the Q binding site, clusters of internal water molecules in the membrane arm, and an α-π transition in a membrane-spanning helix that opens and closes the proton transfer path. Cryo-EM structures of ATP synthase dimers from mammalian, yeast, and Polytomella mitochondria show several rotary states at a resolution of 2.7 to 3.5 Å. The new structures of complex I and ATP synthase are important steps along the way toward understanding the detailed molecular mechanisms of both complexes. Cryo-electron tomography and subtomogram averaging have the potential to resolve their high-resolution structures in situ.
    Keywords:  ATP synthase; complex I; cryo-electron microscopy; cryo-electron tomography; mitochondria; respiratory chain
    DOI:  https://doi.org/10.1146/annurev-biophys-060724-110838
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