Schizosaccharomyces japonicus has low levels of CoQ10 synthesis, respiration deficiency, and efficient ethanol production

Coenzyme Q (CoQ) is essential for mitochondrial respiration and as a cofactor for sulfide 3 quinone reductase. Schizosaccharomyces pombe produces a human-type CoQ10. Here, we 4 analyzed CoQ in other fission yeast species. S. cryophilus and S. octosporus produce 5 CoQ9. S. japonicus produces low levels of CoQ10, although all necessary genes for CoQ 6 synthesis have been identified in its genome. We expressed three genes (dps1, dlp1, and 7 ppt1) for CoQ synthesis from S. japonicus in the corresponding S. pombe mutants, and 8 confirmed that they were functional. S. japonicus had very low levels of oxygen 9 consumption and was essentially respiration defective, probably due to mitochondrial 10 dysfunction. S. japonicus grows well on minimal medium during anaerobic culture, 11 indicating that it acquires sufficient energy by fermentation. S. japonicus produces 12 comparable levels of ethanol under both normal and elevated temperature (42°C) 13 conditions, at which S. pombe is not able to grow.