Mutations in the α Subunit of Eukaryotic Translation Initiation Factor 2 (eIF-2α) that Overcome the Inhibitory Effect of eIF-2α Phosphorylation on Translation Initiation
Abstract
Phosphorylation of eIF-2α in Saccharomyces cerevisiae by the protein kinase GCN2 leads to inhibition of general translation initiation and a specific increase in translation of GCN4 mRNA. We isolated mutations in the eIF-2α structural gene that do not affect the growth rate of wild-type yeast but which suppress the toxic effects of eIF-2α hyperphosphorylation catalyzed by mutationally activated forms of GCN2. These eIF-2α mutations also impair translational derepression of GCN4 in strains expressing wild-type GCN2 protein. All four mutations alter single amino acids within 40 residues of the phosphorylation site in eIF-2α however, three alleles do not decrease the level of eIF-2α phosphorylation. We propose that these mutations alter the interaction between eIF-2 and its recycling factor eukaryotic translation initiation factor 2B (eIF-2B) in a way that diminishes the inhibitory effect of phosphorylated eIF-2 on the essential function of eIF-2B in translation initiation. These mutations may identify a region in eIF-2α that participates directly in a physical interaction with the GCN3 subunit of eIF-2B.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- August 1993
- DOI:
- 10.1073/pnas.90.15.7215
- Bibcode:
- 1993PNAS...90.7215A