Regulation of glycolysis in Kluyveromyces lactis: role of KlGCR1 and KlGCR2 in glucose uptake and catabolism.
In Kluyveromyces lactis, the casein kinase I (Rag8p) regulates the transcription of glycolytic genes and the expression of the low-affinity glucose transporter gene RAG1. This control involves the transcription factor Sck1p, a homologue of Sgc1p of Saccharomyces cerevisiae. SGC1 is known to interact genetically with ScGCR1 and ScGCR2, which code for regulators of glycolytic gene expression. Therefore, we studied the role of KlGCR1 and KlGCR2 genes in K. lactis. The Klgcr1 null mutant could not grow on glucose when respiration was blocked by antimycin A (Rag(- )phenotype). In contrast, the Klgcr2 null mutant could grow under the same conditions, although at a reduced rate. In both mutants, the transcription of glycolytic genes was affected, while that of ribosomal protein genes was not modified. Furthermore, the transcription of the glucose permease genes was also found to be affected in the two mutants, although dissimilarly. While RAG1 transcription decreased at high glucose concentrations, the expression of the high-affinity glucose permease gene HGT1 was unexpectedly impaired under gluconeogenic conditions, in the absence of glucose. Gel mobility shift assays performed with purified maltose-binding protein-KlGcr1p showed that KlGcr1p could interact directly with the promoters of the glycolytic genes, but not with the promoters of the glucose permease genes. Thus, the control exerted by KlGcr1p and KlGcr2p upon glucose transporter genes is probably indirect.
Neil
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H
UMR 5122 CNRS/UCB/INSA, Microbiologie et Génétique, Université Claude Bernard, Bt Lwoff 43, Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France.
Lemaire
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Wésolowski-Louvel
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D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000032:analysis; D047389:Casein Kinase I / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D005656:Fungal Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D016654:Genes, RAG-1 / Q000235:genetics; D005943:Gluconeogenesis / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis / Q000502:physiology*; D007716:Kluyveromyces / Q000235:genetics / Q000378:metabolism*; D058619:Maltose-Binding Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000378:metabolism / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012269:Ribosomal Proteins / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
D002352:Carrier Proteins; D005656:Fungal Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D012269:Ribosomal Proteins; D003609:Dactinomycin; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C031629:phosphoenolpyruvate-glucose phosphotransferase; D047389:Casein Kinase I; D005947:Glucose