Mutants of Eukaryotic Initiation Factor eIF-4E with Altered mRNA Cap Binding Specificity Reprogram mRNA Selection by Ribosomes in Saccharomyces cerevisiae

摘要: Abstract Recognition of the 5′-end eukaryotic mRNA by ribosomal 43 S preinitiation complex involves translation initiation factor eIF-4E (eIF-4α). Deletion mutants gene Saccharomyces cerevisiae (CDC33) encoded proteins with reduced affinity for 5′-cap. One these mutant lacked any detectable binding to a cap analogue column, yet was still able support cell growth. More than 17% total amino acid sequence could be removed without fully inactivating this factor. At least 30 N-terminal acids are not essential function. The minimal functional protein segment therefore comprises at most 176 acids. and growth defects deletion partially compensated increases in synthesis, possibly due mass-action effect on binding. Electroporation yeast spheroplasts vitro synthesized allowed us characterize ability strains distinguish between capped uncapped mRNAs vivo. Our data show that specificity determines what extent translational apparatus differentiates indicate minimum relative (cap) activity required viability.