The p20 and Ded1 proteins have antagonistic roles in eIF4E-dependent translation in Saccharomyces cerevisiae.
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.
de la Cruz
J
J
Département de Biochimie Médicale, CMU, 1, rue Michel Servet, 1211 Genève 4, Switzerland.
Iost
I
I
Kressler
D
D
Linder
P
P
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
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