Figure 4.

Biosynthesis of RQ shares common enzymes with the Q biosynthetic pathway. A, Q biosynthetic pathway in yeast can start from either 4HB or pABA. These pathways share the enzymes Coq1, Coq2, Coq6 (with Yah1 and Arh1), and Coq3. They merge at the common precursor demethyldemethoxyubiquinone (DDMQH₂), which is converted to QH₂ in three steps by Coq5, Coq7, and Coq3, respectively. B, RNAi strains of coq-3, coq-5, and coq-6 C. elegans show significant reduction of both RQ and Q, as compared with the EV and unc-22 controls (Table S1). RNAi of coq-7 significantly reduces Q levels, but RQ biosynthesis is unaffected (Table S1).