title: GI domain-mediated association of the eukaryotic initiation factor 2alpha kinase GCN2 with its activator GCN1 is required for general amino acid control in budding yeast.
abstract: In response to the starvation of a single amino acid, the budding yeast Saccharomyces cerevisiae activates numerous genes involved in various amino acid biosynthetic pathways, all of which are under the control of transcription factor GCN4. This general amino acid control response is based on de-repressed translation of GCN4 mRNA, which is induced by the activation of the eIF2alpha kinase, GCN2. Although it is known that in vivo activation of GCN2 requires GCN1, the mode of GCN1 action remains to be elucidated at the molecular level. Here, we show that GCN2 interacts with GCN1 via the GI domain, a novel protein-binding module that occurs at the N terminus; mutations to conserved residues of this domain abolish its binding to GCN1. Furthermore, the yeast cells with GCN2 defective in interaction with GCN1 fail to display general control response. A similar phenotype is observed in cells overexpressing the GI domain of GCN2 or its target region on GCN1. Thus, GI domain-mediated association of GCN2 to GCN1 is required for general amino acid control. This finding provides the first insight into the molecular mechanism for the activation of GCN2 by GCN1.
authors.affiliation: Division of Genome Biology, Cancer Research Institute, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-0934, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kubota
authors.forename: Y
authors.initials: Y
authors.lastname: Sakaki
authors.forename: T
authors.initials: T
authors.lastname: Ito
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism*; D001665:Binding Sites; D017124:Conserved Sequence; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D010445:Peptide Elongation Factors; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C501389:GCN1 protein, S cerevisiae; D010445:Peptide Elongation Factors; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C512912:GCN2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase