Glucose uptake and catabolite repression in dominant HTR1 mutants of Saccharomyces cerevisiae

• Published in: Journal of Bacteriology Vol. 175; no. 17; pp. 5520 - 5528
• Main Authors: Ozcan, S, Freidel, K, Leuker, A, Ciriacy, M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.09.1993
• Subjects: ARN MENSAJERO; ARN MESSAGER; Bacteriology; Biological and medical sciences; Blotting, Northern; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; Gene Expression Regulation, Fungal; GENES; Genes, Dominant; Genetic Complementation Test; GENETICA; GENETIQUE; GLUCOSA; GLUCOSE; Glucose - metabolism; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Kinetics; Maltose - metabolism; METABOLISME DES GLUCIDES; METABOLISMO DE CARBOHIDRATOS; Microbiology; Monosaccharide Transport Proteins - metabolism; MUTANT; MUTANTES; Mutation; Mycology; PROTEINAS; PROTEINE; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Suppression, Genetic; Triose-Phosphate Isomerase - antagonists & inhibitors; Triose-Phosphate Isomerase - genetics; Yeast; Yeast; Glucose; Gene expression; Metabolism; Uptake; Fungi; Regulation(control); Gene; Membrane transport; Ascomycetes; Mutation; Saccharomyces cerevisiae; Carrier protein; Thallophyta; Catabolic repression
• ISSN: 0021-9193; 1098-5530; 1067-8832
• DOI: 10.1128/jb.175.17.5520-5528.1993

Growth and carbon metabolism in triosephosphate isomerase mutants of Saccharomyces cerevisiae are severely inhibited by glucose. By using this feature, we selected for secondary site revertants on glucose. We defined five complementation groups, some of which have previously been identified as glucose repression mutants. The predominant mutant type, HTR1 (hexose transport regulation), is dominant and causes various glucose-specific metabolic and regulatory defects in TPI1 wild-type cells. HTR1 mutants are deficient in high-affinity glucose uptake and have reduced low-affinity transport. Transcription of various known glucose transporter genes (HXT1, HXT3, and HXT4) was defective in HTR1 mutants, leading us to suggest that HTR mutations affect a negative factor of HXT gene expression. By contrast, transcript levels for SNF3, which encodes a component of high-affinity glucose uptake, were unaffected. We presume that HTR1 mutations affect a negative factor of HXT gene expression. Multicopy expression of HXT genes or parts of their regulatory sequences suppresses the metabolic defects of HTR1 mutants but not their derepressed phenotype at high glucose concentrations. This suggests that the glucose repression defect is not a direct result of the metabolically relevant defect in glucose transport. Alternatively, some unidentified regulatory components of the glucose transport system may be involved in the generation or transmission of signals for glucose repression