title: Respiratory-induced coenzyme Q biosynthesis is regulated by a phosphorylation cycle of Cat5p/Coq7p.
abstract: CoQ(6) (coenzyme Q(6)) biosynthesis in yeast is a well-regulated process that requires the final conversion of the late intermediate DMQ(6) (demethoxy-CoQ(6)) into CoQ(6) in order to support respiratory metabolism in yeast. The gene CAT5/COQ7 encodes the Cat5/Coq7 protein that catalyses the hydroxylation step of DMQ(6) conversion into CoQ(6). In the present study, we demonstrated that yeast Coq7 recombinant protein purified in bacteria can be phosphorylated in vitro using commercial PKA (protein kinase A) or PKC (protein kinase C) at the predicted amino acids Ser(20), Ser(28) and Thr(32). The total absence of phosphorylation in a Coq7p version containing alanine instead of these phospho-amino acids, the high extent of phosphorylation produced and the saturated conditions maintained in the phosphorylation assay indicate that probably no other putative amino acids are phosphorylated in Coq7p. Results from in vitro assays have been corroborated using phosphorylation assays performed in purified mitochondria without external or commercial kinases. Coq7p remains phosphorylated in fermentative conditions and becomes dephosphorylated when respiratory metabolism is induced. The substitution of phosphorylated residues to alanine dramatically increases CoQ(6) levels (256%). Conversely, substitution with negatively charged residues decreases CoQ(6) content (57%). These modifications produced in Coq7p also alter the ratio between DMQ(6) and CoQ(6) itself, indicating that the Coq7p phosphorylation state is a regulatory mechanism for CoQ(6) synthesis.
authors.affiliation: Departamento de Fisiología, Anatomía y Biología Celular, Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-CSIC, CIBERER Instituto de Salud Carlos III, Sevilla 41013, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Martín-Montalvo
authors.forename: Isabel
authors.initials: I
authors.lastname: González-Mariscal
authors.forename: Sergio
authors.initials: S
authors.lastname: Padilla
authors.forename: Manuel
authors.initials: M
authors.lastname: Ballesteros
authors.forename: David L
authors.initials: DL
authors.lastname: Brautigan
authors.forename: Plácido
authors.initials: P
authors.lastname: Navas
authors.forename: Carlos
authors.initials: C
authors.lastname: Santos-Ocaña
mesh_terms: D000595:Amino Acid Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004579:Electron Transport; D008928:Mitochondria / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D014451:Ubiquinone / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: C097734:CAT5 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C032165:ubiquinone 6; D014451:Ubiquinone; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C030777:ubiquinone 7