Moe1 and spInt6, the Fission Yeast Homologues of Mammalian Translation Initiation Factor 3 Subunits p66 (eIF3d) and p48 (eIF3e), Respectively, Are Required for Stable Association of eIF3 Subunits

• Published in: The Journal of biological chemistry Vol. 277; no. 3; pp. 2360 - 2367
• Main Authors: Bandyopadhyay, Amitabha, Lakshmanan, Viswanathan, Matsumoto, Tomohiro, Chang, Eric C., Maitra, Umadas
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.01.2002; American Society for Biochemistry and Molecular Biology
• Subjects: Carrier Proteins - physiology; Eukaryotic Initiation Factors; initiation factor eIF-3; initiation factor eIF3; moe1 gene; Moe1 protein; Peptide Initiation Factors - chemistry; Peptide Initiation Factors - metabolism; Phenotype; Prokaryotic Initiation Factor-3; Protein Biosynthesis - physiology; Schizosaccharomyces - metabolism; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - chemistry; Schizosaccharomyces pombe Proteins - metabolism; Schizosaccharomyces pombe Proteins - physiology; spInt6 protein
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M107790200

The protein encoded by the fission yeast gene,moe1+ is the homologue of the p66/eIF3d subunit of mammalian translation initiation factor eIF3. In this study, we show that in fission yeast, Moe1 physically associates with eIF3 core subunits as well as with 40 S ribosomal particles as a constituent of the eIF3 protein complex that is similar in size to multisubunit mammalian eIF3. However, strains lacking moe1+(Δmoe1) are viable and show no gross defects in translation initiation, although the rate of translation in theΔmoe1 cells is about 30–40% slower than wild-type cells. Mutant Δmoe1 cells are hypersensitive to caffeine and defective in spore formation. These phenotypes ofΔmoe1 cells are similar to those reported previously for deletion of the fission yeast int6+ gene that encodes the fission yeast homologue of the p48/Int6/eIF3e subunit of mammalian eIF3. Further analysis of eIF3 subunits inΔmoe1 or Δint6 cells shows that in these deletion strains, while all the eIF3 subunits are bound to 40 S particles, dissociation of ribosome-bound eIF3 results in the loss of stable association between the eIF3 subunits. In contrast, eIF3 isolated from ribosomes of wild-type cells are associated with one another in a protein complex. These observations suggest that Moe1 and spInt6 are each required for stable association of eIF3 subunits in fission yeast.