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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: Biochim Biophys Acta. 2015 May 23;1851(9):1227–1239. doi: 10.1016/j.bbalip.2015.05.003

Fig. 1. Biosynthesis of Q in S. cerevisiae from 4HB or pABA.

Fig. 1

S. cerevisiae uses either 4-hydoxybenzoic acid (4HB) or para-aminobenzoic acid (pABA) as an aromatic ring precursor for Q6 biosynthesis. Coq1 synthesizes the hexaprenyl-diphosphate tail and Coq2 attaches it to either ring. Coq6 performs the C5-hydoxylation reaction in concert with ferredoxin (Yah1) and ferredoxin reductase (Arh1). Coq3 catalyzes the two O-methylation steps and Coq5 catalyzes the C-methylation step. Coq9 is the putative deaminase that removes the amino groups on imino-demethyl-demethoxy-Q6 (IDDMQ6) or imino-demethoxy-Q6 (IDMQ6). Coq9 is also required for Coq7 to catalyze the penultimate hydroxylation step, and for efficient C5-hydroxylation by Coq6.