bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2025–05–11
two papers selected by
Gavin McStay, Liverpool John Moores University



  1. Plant Cell. 2025 May 05. pii: koaf101. [Epub ahead of print]
      Photosynthetic organisms use sunlight as an energy source but rely on respiration during the night and in non-photosynthetic tissues. Respiration also occurs in photosynthetically active cells, where its role is still unclear due to the lack of viable mutants. Mutations abolishing cytochrome c oxidase (complex IV) activity are generally lethal. In this study we generated cytochrome c oxidase assembly protein 11 (cox11) knockout lines through vegetative propagation in the moss Physcomitrium patens. These mutants showed severely impaired growth, with an altered composition of the respiratory apparatus and increased electron transfer through alternative oxidase. The light phase of photosynthesis remained largely unaffected in cox11 plants, while the efficiency of carbon fixation was reduced. Transcriptomic and metabolomic analyses showed that disrupting the cytochrome pathway had broad consequences for carbon and nitrogen metabolism. A major alteration in nitrogen assimilation was observed, with a general reduction in amino acid abundance. Partial growth rescue was achieved by externally supplying plants with amino acids but not with sugars, demonstrating that respiration in photosynthetic plant cells plays an essential role at the interface between carbon and nitrogen metabolism and a key role in providing carbon skeletons for amino acid biosynthesis.
    DOI:  https://doi.org/10.1093/plcell/koaf101
  2. PLoS One. 2025 ;20(5): e0323136
      Complex V of the mitochondrial oxidative phosphorylation system is an ATP synthase that plays a pivotal role in the cell's energy transduction. Mutations in genes encoding the multiple protein subunits that constitute complex V cause severe metabolic and neurodegenerative diseases. We present here three complementary assays to assess Complex V activity and assembly in peripheral blood mononuclear cells (PBMCs). The assays involve spectrophotometric and in-gel activity measurements, cytochemical assessment of the mitochondrial transmembrane electrochemical gradient (∆Ѱm) to determine if the enzyme acts forward as an ATP synthase or in reverse as an ATPase, and western blot analysis of clear native gels to evaluate Complex V assembly. The whole process can be performed with 2 × 106 PBMCs isolated from ~2 ml of blood. Our study suggests that PBMCs can serve as a platform for small-scale, minimally invasive investigations of patients suspected of Complex V deficiency or in biomarker research of mitochondrial function.
    DOI:  https://doi.org/10.1371/journal.pone.0323136