Ubiquinone (UQ) is an essential player in the respiratory electron transfer system. In Saccharomyces cerevisiae strains lacking the ability to synthesize UQ₆, exogenously supplied UQs can be taken up and delivered to mitochondria through an unknown mechanism, restoring the growth of UQ₆-deficient yeast in non-fermentable medium. Since elucidating the mechanism responsible may markedly contribute to therapeutic strategies for patients with UQ deficiency, many attempts have been made to identify the machinery involved in UQ trafficking in the yeast model. However, definite experimental evidence of the direct interaction of UQ with a specific protein(s) has not yet been demonstrated. To gain insight into intracellular UQ trafficking via a chemistry-based strategy, we synthesized a hydrophobic UQ probe (pUQ5), which has a photoreactive diazirine group attached to a five-unit isoprenyl chain and a terminal alkyne to visualize and/or capture the labeled proteins via click chemistry. pUQ5 successfully restored the growth of UQ₆-deficient S. cerevisiae (Δcoq2) on a non-fermentable carbon source, indicating that this UQ was taken up and delivered to mitochondria, and served as a UQ substrate of respiratory enzymes. Through photoaffinity labeling of the mitochondria isolated from Δcoq2 yeast cells cultured in the presence of pUQ5, we identified many labeled proteins, including voltage-dependent anion channel 1 (VDAC1) and cytochrome c oxidase subunit 3 (Cox3). The physiological relevance of UQ binding to these proteins is discussed.

• PMID: 38906315
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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Mizutani M, Kuroda S, Oku M, Aoki W, Masuya T, Miyoshi H, Murai M

Primary Lit For

COX3 | POR1 | COQ2

Additional Lit For

COX1 | COB | Mitochondrial respiratory chain complex III | Mitochondrial respiratory chain complex IV, COX5A variant | Mitochondrial respiratory chain complex IV, COX5B variant

Review For