title: Characterization of a mitochondrial inorganic pyrophosphatase in Saccharomyces cerevisiae.
abstract: We have studied a mitochondrial inorganic pyrophosphatase (PPase) in the yeast Saccharomyces cerevisiae. The uncoupler FCCP (carbonyl cyanide p-trifluoromethoxyphenylhydrazone) and the ionophores valinomycin and nigericin stimulate the PPase activity of repeatedly washed yeast mitochondria 2-3-fold. We have previously cloned a yeast gene, PPA2, encoding the catalytic subunit of a mitochondrial PPase. Uncouplers stimulate the PPase activity several-fold in mitochondria from both cells that overexpress PPA2 from a high copy number plasmid and cells with normal expression. These results indicate that the PPA2 polypeptide functions as an energy linked and membrane associated PPase. The stimulation of mitochondrial PPase activity by FCCP, but not by valinomycin and nigericin, was greatly enhanced by the presence of DTT. The antibiotics Dio-9, equisetin and the F0F1-ATPase inhibitor oligomycin also increase mitochondrial PPase activity several fold. This stimulation is much higher, whereas basal PPase activity is lower, in isotonic than in hypotonic solution, which indicates that intact membranes are a prerequisite for maximal effects.
authors.affiliation: Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, University of Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Lundin
authors.forename: S W
authors.initials: SW
authors.lastname: Deopujari
authors.forename: L
authors.initials: L
authors.lastname: Lichko
authors.forename: L P
authors.initials: LP
authors.lastname: da Silva
authors.forename: H
authors.initials: H
authors.lastname: Baltscheffsky
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D009550:Nigericin / Q000494:pharmacology; D009930:Organic Chemicals; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013367:Submitochondrial Particles / Q000201:enzymology; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013764:Tetrahydronaphthalenes; D014475:Uncoupling Agents / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D008565:Membrane Proteins; D009930:Organic Chemicals; D011760:Pyrrolidinones; D013438:Sulfhydryl Compounds; D013764:Tetrahydronaphthalenes; D014475:Uncoupling Agents; C100056:DIO 9; D014634:Valinomycin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C024509:equisetin; D000251:Adenosine Triphosphatases; D011755:Pyrophosphatases; D009550:Nigericin