Characterization of the second external alternative dehydrogenase from mitochondria of the respiratory yeast Kluyveromyces lactis.
The mitochondria of the respiratory yeast Kluyveromyces lactis are able to reoxidize cytosolic NADPH. Previously, we characterized an external alternative dehydrogenase, KlNde1p, having this activity. We now characterize the second external alternative dehydrogenase of K. lactis mitochondria, KlNde2p. We examined its role in cytosolic NADPH reoxidation by studying heterologous expression of KlNDE2 in Saccharomyces cerevisiae mutants and by constructing Deltaklnde1 and Deltaklnde2 mutants. KlNde2p uses NADH or NADPH as substrates, its activity in isolated mitochondria is not regulated by exogenously added calcium and it is not down-regulated when the cells grow in glucose versus lactate. KlNde2p shows lower affinity for NADPH than KlNde1p. Both enzymes show similar pH optimum.
Tarrío
Nuria
N
Department of Molecular and Cell Biology, University of A Coruña, Campus da Zapateira s/n, 15071-A Coruña, Spain.
Cerdán
M Esperanza
ME
González Siso
M Isabel
MI
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D006863:Hydrogen-Ion Concentration; D007716:Kluyveromyces / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010101:Oxygen Consumption; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D010088:Oxidoreductases; D002118:Calcium