The nuclear genes encoding the internal (KlNDI1) and external (KlNDE1) alternative NAD(P)H:ubiquinone oxidoreductases of mitochondria from Kluyveromyces lactis.
Cloning, sequence and functional analyses of the Kluyveromyces lactis genes KlNDI1 and KlNDE1 are reported. These genes encode for proteins with high homology to the mitochondrial internal (Ndi1p) and external (Nde1p) alternative NADH:ubiquinone oxidoreductases from Saccharomyces cerevisiae and complement the respective mutations. Analysis of KlNDI1 transcriptional regulation showed that expression of this gene is lower in 2% glucose than in 0.5% glucose or non-fermentable carbon sources. Beta-galactosidase activity values, shown by lacZ fusions of KlNDI1 promoter deletions, suggested that two Adr1p binding sites mediate this carbon source regulation of KlNDI1. The expression of the KlNDE1 gene in S. cerevisiae mutant strains and measurement of respiration with isolated mitochondria showed that the protein encoded by KlNDE1 oxidizes NADPH, this being an important difference with respect to the conventional yeast S. cerevisiae. Moreover, Northern blot experiments using a phosphoglucose isomerase mutant showed that KlNDE1 gene transcription increases with glucose metabolism through the pentose phosphate pathway.
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Department of Molecular and Cell Biology, University of A Coruña, Campus da Zapateira s/n. 15071- A Coruña, Spain.
Díaz Prado
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Cerdán
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González Siso
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D000595:Amino Acid Sequence; D002244:Carbon / Q000378:metabolism; D003001:Cloning, Molecular; D042967:Electron Transport Complex I / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism; D007716:Kluyveromyces / Q000201:enzymology* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010427:Pentose Phosphate Pathway; D014158:Transcription, Genetic
D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D002244:Carbon; D042967:Electron Transport Complex I; D005947:Glucose