title: The p20 and Ded1 proteins have antagonistic roles in eIF4E-dependent translation in Saccharomyces cerevisiae.
abstract: The translation initiation factor eIF4E mediates the binding of the small ribosomal subunit to the cap structure at the 5' end of the mRNA. In Saccharomyces cerevisiae, the cap-binding protein eIF4E is mainly associated with eIF4G, forming the cap-binding complex eIF4F. Other proteins are detected upon purification of the complex on cap-affinity columns. Among them is p20, a protein of unknown function encoded by the CAF20 gene. Here, we show a negative regulatory role for the p20 protein in translation initiation. Deletion of CAF20 partially suppresses mutations in translation initiation factors. Overexpression of the p20 protein results in a synthetic enhancement of translation mutation phenotypes. Similar effects are observed for mutations in the DED1 gene, which we have isolated as a multicopy suppressor of a temperature-sensitive eIF4E mutation. The DED1 gene encodes a putative RNA helicase of the DEAD-box family. The analyses of its suppressor activity, of polysome profiles of ded1 mutant strains, and of synthetic lethal interactions with different translation mutants indicate that the Ded1 protein has a role in translation initiation in S. cerevisiae.
authors.affiliation: Département de Biochimie Médicale, CMU, 1, rue Michel Servet, 1211 Genève 4, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: de la Cruz
authors.forename: I
authors.initials: I
authors.lastname: Iost
authors.forename: D
authors.initials: D
authors.lastname: Kressler
authors.forename: P
authors.initials: P
authors.lastname: Linder
mesh_terms: D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli; D039561:Eukaryotic Initiation Factor-4E; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005804:Genes, Lethal; D016153:Genes, Suppressor; D016296:Mutagenesis; D010448:Peptide Initiation Factors / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D039381:RNA Cap-Binding Proteins; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013696:Temperature
chemical_list: D017931:DNA Primers; D039561:Eukaryotic Initiation Factor-4E; D010448:Peptide Initiation Factors; D039381:RNA Cap-Binding Proteins; D016601:RNA-Binding Proteins; D012316:RNA Nucleotidyltransferases; D020365:RNA Helicases