Characterization of Shy1, the Schizosaccharomyces pombe homolog of human SURF1

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.