title: Yeast Coq9 controls deamination of coenzyme Q intermediates that derive from para-aminobenzoic acid.
abstract: Coq9 is a polypeptide subunit in a mitochondrial multi-subunit complex, termed the CoQ-synthome, required for biosynthesis of coenzyme Q (ubiquinone or Q). Deletion of COQ9 results in dissociation of the CoQ-synthome, but over-expression of Coq8 putative kinase stabilizes the CoQ-synthome in the coq9 null mutant and leads to the accumulation of two nitrogen-containing Q intermediates, imino-demethoxy-Q6 (IDMQ6) and 3-hexaprenyl-4-aminophenol (4-AP) when para-aminobenzoic acid (pABA) is provided as a ring precursor. To investigate whether Coq9 is responsible for deamination steps in Q biosynthesis, we utilized the yeast coq5-5 point mutant. The yeast coq5-5 point mutant is defective in the C-methyltransferase step of Q biosynthesis but retains normal steady-state levels of the Coq5 polypeptide. Here, we show that when high amounts of 13C6-pABA are provided, the coq5-5 mutant accumulates both 13C6-imino-demethyl-demethoxy-Q6 (13C6-IDDMQ6) and 13C6-demethyl-demethoxy-Q6 (13C6-DDMQ6). Deletion of COQ9 in the yeast coq5-5 mutant along with Coq8 over-expression and 13C6- pABA labeling leads to the absence of 13C6-DDMQ6, and the nitrogen-containing intermediates 13C6-4-AP and 13C6-IDDMQ6 persist. We describe a coq9 temperature-sensitive mutant and show that at the non-permissive temperature, steady-state polypeptide levels of Coq9-ts19 increased, while Coq4, Coq5, Coq6, and Coq7 decreased. The coq9-ts19 mutant had decreased Q6 content and increased levels of nitrogen-containing intermediates. These findings identify Coq9 as a multi-functional protein that is required for the function of Coq6 and Coq7 hydroxylases, for removal of the nitrogen substituent from pABA-derived Q intermediates, and is an essential component of the CoQ synthome.
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, USA 90095-1569.
authors.forename: Cuiwen H
authors.initials: CH
authors.lastname: He
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, USA 90095-1569.
authors.forename: Dylan S
authors.initials: DS
authors.lastname: Black
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, USA 90095-1569.
authors.forename: Theresa P T
authors.initials: TP
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, USA 90095-1569.
authors.forename: Charles
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Fullerton, Fullerton, CA, USA 92834.
authors.forename: Chandra
authors.initials: C
authors.lastname: Srinivasan
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, USA 90095-1569. Electronic address: cathy@chem.ucla.edu.
authors.forename: Catherine F
authors.initials: CF
authors.lastname: Clarke
mesh_terms: D010129:4-Aminobenzoic Acid / Q000378:metabolism*; D003641:Deamination; D015966:Gene Expression Regulation, Fungal; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D017354:Point Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013696:Temperature; D014451:Ubiquinone / Q000235:genetics / Q000378:metabolism*
chemical_list: C433869:COQ4 protein, S cerevisiae; C099891:COQ8 protein, S cerevisiae; C521712:Coq9 protein, S cerevisiae; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; C032165:ubiquinone 6; D014451:Ubiquinone; C105459:COQ5 protein, S cerevisiae; D008780:Methyltransferases; C030777:ubiquinone 7; D010129:4-Aminobenzoic Acid
keywords: Coenzyme Q; Mass spectrometry (MS); Mitochondrial metabolism; Q biosynthetic intermediates; Saccharomyces cerevisiae; Temperature-sensitive mutant