bims-resufa Biomed News
on Respiratory supercomplex factors
Issue of 2024–09–22
two papers selected by
Gavin McStay, Liverpool John Moores University
  1. Characterization of Shy1, the Schizosaccharomyces pombe homolog of human SURF1.
  2. Electron transfer in the respiratory chain at low salinity.
  1. Sci Rep. 2024 09 17. 14(1): 21678
    Characterization of Shy1, the Schizosaccharomyces pombe homolog of human SURF1.
    Ying Luo, Yuanqi Xu, Fawad Ahmad, Gang Feng, Ying Huang.
      Cytochrome c oxidase (complex IV) is the terminal enzyme in the mitochondrial respiratory chain. As a rare neurometabolic disorder caused by mutations in the human complex IV assembly factor SURF1, Leigh Syndrome (LS) is associated with complex IV deficiency. In this study, we comprehensively characterized Schizosaccharomyces pombe Shy1, the homolog of human SURF1. Bioinformatics analysis revealed that Shy1 contains a conserved SURF1 domain that links to the biogenesis of complex IV and shares high structural similarity with its homologs in Saccharomyces cerevisiae and humans. Our study showed that Shy1 is required for the expression of mtDNA-encoded genes and physically interacts with structural subunits and assembly factors of complex IV. Interestingly, Rip1, the subunit of ubiquinone-cytochrome c oxidoreductase or cytochrome bc1 complex (complex III), can also co-immunoprecipitate with Shy1, suggesting Shy1 may be involved in the assembly of the mitochondrial respiratory chain supercomplexes. This conclusion is further corroborated by our BN-PAGE analysis. Unlike its homologs, deletion of shy1 does not critically disrupt respiratory chain assembly, indicating the presence of the compensatory mechanism(s) within S. pombe that ensure mitochondrial functionality. Collectively, our investigation elucidates that Shy1 plays a pivotal role in the sustainability of the regular function of mitochondria by participating in the assembly of complex IV in S. pombe.
    Keywords:   Schizosaccharomyces pombe ; SURF1; Shy1; cytochrome c oxidase; mitochondria
    DOI:  https://doi.org/10.1038/s41598-024-72681-9
  2. Nat Commun. 2024 Sep 19. 15(1): 8241
    Electron transfer in the respiratory chain at low salinity.
    Ana Paula Lobez, Fei Wu, Justin M Di Trani, John L Rubinstein, Mikael Oliveberg, Peter Brzezinski, Agnes Moe.
      Recent studies have established that cellular electrostatic interactions are more influential than assumed previously. Here, we use cryo-EM and perform steady-state kinetic studies to investigate electrostatic interactions between cytochrome (cyt.) c and the complex (C) III2-IV supercomplex from Saccharomyces cerevisiae at low salinity. The kinetic studies show a sharp transition with a Hill coefficient ≥2, which together with the cryo-EM data at 2.4 Å resolution indicate multiple cyt. c molecules bound along the supercomplex surface. Negatively charged loops of CIII2 subunits Qcr6 and Qcr9 become structured to interact with cyt. c. In addition, the higher resolution allows us to identify water molecules in proton pathways of CIV and, to the best of our knowledge, previously unresolved cardiolipin molecules. In conclusion, the lowered electrostatic screening renders engagement of multiple cyt. c molecules that are directed by electrostatically structured CIII2 loops to conduct electron transfer between CIII2 and CIV.
    DOI:  https://doi.org/10.1038/s41467-024-52475-3
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