Mutations in the alpha subunit of eukaryotic translation initiation factor 2 (eIF-2 alpha) that overcome the inhibitory effect of eIF-2 alpha phosphorylation on translation initiation

Proc Natl Acad Sci U S A. 1993 Aug 1;90(15):7215-9. doi: 10.1073/pnas.90.15.7215.

Abstract

Phosphorylation of eIF-2 alpha 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-2 alpha structural gene that do not affect the growth rate of wild-type yeast but which suppress the toxic effects of eIF-2 alpha hyperphosphorylation catalyzed by mutationally activated forms of GCN2. These eIF-2 alpha 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-2 alpha; however, three alleles do not decrease the level of eIF-2 alpha 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-2 alpha that participates directly in a physical interaction with the GCN3 subunit of eIF-2B.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Eukaryotic Initiation Factor-2 / chemistry
  • Eukaryotic Initiation Factor-2 / metabolism*
  • Gene Expression Regulation, Fungal
  • Genes, Suppressor
  • Guanine Nucleotide Exchange Factors
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides / chemistry
  • Peptide Chain Initiation, Translational*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / metabolism
  • Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Structure-Activity Relationship
  • eIF-2 Kinase

Substances

  • Eukaryotic Initiation Factor-2
  • Guanine Nucleotide Exchange Factors
  • Oligodeoxyribonucleotides
  • Proteins
  • Protein Serine-Threonine Kinases
  • eIF-2 Kinase