title: Kinetic activation of yeast mitochondrial D-lactate dehydrogenase by carboxylic acids.
abstract: Aerobically grown yeast cells express mitochondrial lactate dehydrogenases that localize to the mitochondrial inner membrane. The D-lactate dehydrogenase is a zinc-flavoprotein with high acceptor specificity for cytochrome c, that catalyzes the oxidation of D-lactate into pyruvate. In this paper, we show that mitochondrial respiratory rate in phosphorylating or non-phosphorylating conditions with D-lactate as substrate is stimulated by carboxylic acids. This stimulation does not affect the yield of oxidative phosphorylation. Furthermore, this stimulation lies at the level of the D-lactate dehydrogenase. It is non-competitive, hyperbolic and its dimension is directly related to the number of carboxylic groups on the activator. The physiological meaning of such a regulation is discussed.
authors.affiliation: Université Bordeaux 2, Bordeaux cedex, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Mourier
authors.forename: Julie
authors.initials: J
authors.lastname: Vallortigara
authors.forename: Edgar D
authors.initials: ED
authors.lastname: Yoboue
authors.forename: Michel
authors.initials: M
authors.lastname: Rigoulet
authors.forename: Anne
authors.initials: A
authors.lastname: Devin
mesh_terms: D002264:Carboxylic Acids / Q000378:metabolism*; D019069:Cell Respiration / Q000502:physiology; D003576:Electron Transport Complex IV / Q000378:metabolism; D004789:Enzyme Activation; D045022:Lactate Dehydrogenases / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D010085:Oxidative Phosphorylation; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D008293:Malates; D029701:Saccharomyces cerevisiae Proteins; C030298:malic acid; D045022:Lactate Dehydrogenases; C071195:D-lactate dehydrogenase; D003576:Electron Transport Complex IV