title: Saccharomyces cerevisiae IRE2/HAC1 is involved in IRE1-mediated KAR2 expression.
abstract: The Saccharomyces cerevisiae IRE1 gene, encoding a putative receptor-type protein kinase, is known to be required for inositol prototrophy and for the induction of a chaperon molecule, BiP, encoded by KAR2, under stress conditions such as tunicamycin addition. We have characterized a yeast gene, IRE2, which was isolated as a suppressor gene that complements the inositol auxotrophic phenotype of the ire1 mutation. Sequencing analysis revealed that IRE2 is identical to HAC1, which encodes a transcription factor having a basic-leucine zipper motif. Introduction of IRE2/HAC1 into the ire1 mutant clearly restored the expression of KAR2 upon tunicamycin treatment. ire2/hac1-disrupted yeast cells showed not only the inositol auxotrophic phenotype but also the tunicamycin sensitivity, and failed to induce the expression of KAR2. These results clearly indicate that the IRE2/HAC1 gene product plays a critical role in the induction of KAR2 expression and in the inositol prototrophy mediated by IRE1.
authors.affiliation: Department of Biochemical Engineering and Science, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, Japan. nikawa@bse.kyutech.ac.jp
authors.forename: J
authors.initials: J
authors.lastname: Nikawa
authors.forename: M
authors.initials: M
authors.lastname: Akiyoshi
authors.forename: S
authors.initials: S
authors.lastname: Hirata
authors.forename: T
authors.initials: T
authors.lastname: Fukuda
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D050976:Basic-Leucine Zipper Transcription Factors; D019281:Dimerization; D004926:Escherichia coli; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014415:Tunicamycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D050976:Basic-Leucine Zipper Transcription Factors; D005656:Fungal Proteins; C091341:HAC1 protein, S cerevisiae; D018840:HSP70 Heat-Shock Proteins; C060153:KAR2 protein, yeast; D008562:Membrane Glycoproteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014415:Tunicamycin; C082863:IRE1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases