María Isabel González Siso

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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(More)
Kluyveromyces lactis mutants defective in the glycolytic enzyme phosphoglucose isomerase are able to grow in glucose media and to produce ethanol, but they depend on a functional respiratory chain and do not grow in glucose-antimycin media. We postulate that this is due to the necessity of reoxidizing, in the mitochondria, the NADPH produced by the pentose(More)
Lipolytic enzymes catalyze the hydrolysis of ester bonds in the presence of water. In media with low water content or in organic solvents, they can catalyze synthetic reactions such as esterification and transesterification. Lipases and esterases, in particular those from extremophilic origin, are robust enzymes, functional under the harsh conditions of(More)
Saccharomyces cerevisiae and Kluyveromyces lactis are considered to be the prototypes of two distinct metabolic models of facultatively-aerobic yeasts: Crabtree-positive/fermentative and Crabtree-negative/respiratory, respectively. Our group had previously proposed that one of the molecular keys supporting this difference lies in the mechanisms involved in(More)
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(More)
Secretion of the heterologous Kluyveromyces lactis beta-galactosidase into culture medium by several Saccharomyces cerevisiae osmotic-remedial thermosensitive-autolytic mutants was assayed and proved that new metabolic abilities were conferred since the constructed strains were able to grow in lactose-containing media. Cell growth became independent of a(More)
The yeast Saccharomyces cerevisiae has been previously used as a model eukaryotic system to identify genes related to drug resistance. Deletion of the IXR1 gene increases resistance to cisplatin, and deletion of the SKY1 gene increases resistance to cisplatin and spermine. Three S. cerevisiae strains and their derivatives, carrying single Δixr1 and Δsky1(More)
A new polymerase chain reaction (PCR)-based method is described for the isolation of clones of interest from a library when only part of a sequence is available. In actuality, this occurs with many genomes that have been partially sequenced using a random strategy. The method presented here, discriminating clusters by PCR (DCbyPCR), is a nonradioactive and(More)
Cloning and transcriptional regulation of the KlFBA1 gene that codes for the class II fructose-1,6-bisphosphate aldolase of the yeast Kluyveromyces lactis are described. KlFBA1 mRNA diminishes transiently during the shift from hypoxic to fully aerobic conditions and increases in the reversal shift. This regulation is mediated by heme since expression was(More)
Response to oxidative stress has been hitherto scarcely studied in the respiratory yeast Kluyveromyces lactis. The genes coding for reductases of glutathione and thioredoxin, KlGLR1 and KlTRR1, respectively, have been cloned and characterized in this work. H(2)O(2) treatment increased transcription and enzyme activity of KlTRR1 but not of KlGLR1, suggesting(More)