title: Derepression of gene expression mediated by the 5' upstream region of the isocitrate lyase gene of Candida tropicalis is controlled by two distinct regulatory pathways in Saccharomyces cerevisiae.
abstract: The 5' upstream region of the gene encoding isocitrate lyase of Candida tropicalis (UPR-ICL) is functional as a promoter in Saccharomyces cerevisiae, and it is regulated by carbon source; the expression of the gene is repressed when cells are grown on glucose, while it increases to a higher level in acetate-grown cells. Therefore, we have investigated regions in UPR-ICL responsible for gene expression in glucose-grown and acetate-grown cells. In glucose-grown cells, a deletion of the region between -801 and -569 (region G1) significantly decreased gene expression compared with that observed with the complete UPR-ICL. The region from -421 to -379 (region G2) also repressed gene expression in glucose-grown cells. In acetate-grown cells, two regions were found to strongly enhance gene expression, one between -728 and -569 (region A1) and the other between -370 and -356 (region A2). Whereas region A2 contained a sequence motif similar to the carbon-source-responsive element (CSRE), which mediates regulation by carbon source of S. cerevisiae ICL1, region A1 did not show similarity to any reported cis-acting elements. Deletion mutants of UPR-ICL containing only one of these regions showed that each region could independently activate gene expression to a similar level when the cells were grown on acetate. The influences of null mutations in the MIG1, SNF1 and CAT8 genes on regulation of UPR-ICL-mediated gene expression were examined. Expression of the ICL gene with full-length UPR-ICL increased about tenfold in mig1 cells grown on glucose, while little difference was observed in acetate-grown cells. The effects of snf1 and cat8 mutations were different between region-A1-mediated and region-A2-mediated gene expression in acetate-grown cells. Region-A2-mediated expression decreased 95% and 86% in snf1 and cat8 cells, respectively, while region-A1-mediated expression decreased 72% in snf1 cells and was not affected by the cat8 mutation. This finding indicates that region-A1-mediated gene expression is regulated by a pathway independent of CAT8, which is necessary for derepression of CSRE-mediated gene expression in S. cerevisiae.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Umemura
authors.forename: H
authors.initials: H
authors.lastname: Atomi
authors.forename: T
authors.initials: T
authors.lastname: Kanai
authors.forename: S
authors.initials: S
authors.lastname: Takeshita
authors.forename: N
authors.initials: N
authors.lastname: Kanayama
authors.forename: M
authors.initials: M
authors.lastname: Ueda
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
mesh_terms: D001483:Base Sequence; D002175:Candida / Q000201:enzymology* / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D007522:Isocitrate Lyase / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
chemical_list: D012097:Repressor Proteins; D007522:Isocitrate Lyase; D005947:Glucose