Vitamin K2 cannot substitute Coenzyme Q10 as electron carrier in the mitochondrial respiratory chain of mammalian cells

摘要

Coenzyme Qsub10/sub (CoQsub10/sub) deficiencies are a group of heterogeneous conditions that respond to ubiquinone administration if treated soon after the onset of symptoms. However, this treatment is only partially effective due to its poor bioavailability. We tested whether vitamin K2, which was reported to act as a mitochondrial electron carrier in D. melanogaster, could mimic ubiquinone function in human CoQsub10/sub deficient cell lines, and in yeast carrying mutations in genes required for coenzyme Qsub6/sub (CoQsub6/sub) biosynthesis. We found that vitamin K2, despite entering into mitochondria, restored neither electron flow in the respiratory chain, nor ATP synthesis. Conversely, coenzyme Qsub4/sub (CoQsub4/sub), an analog of CoQsub10/sub with a shorter isoprenoid side chain, could efficiently substitute its function. Given its better solubility, CoQsub4/sub could represent an alternative to CoQsub10/sub in patients with both primary and secondary CoQsub10/sub deficiencies.