Recycling of eukaryotic posttermination ribosomal complexes

Cell. 2007 Oct 19;131(2):286-99. doi: 10.1016/j.cell.2007.08.041.

Abstract

After translational termination, mRNA and P site deacylated tRNA remain associated with ribosomes in posttermination complexes (post-TCs), which must therefore be recycled by releasing mRNA and deacylated tRNA and by dissociating ribosomes into subunits. Recycling of bacterial post-TCs requires elongation factor EF-G and a ribosome recycling factor RRF. Eukaryotes do not encode a RRF homolog, and their mechanism of ribosomal recycling is unknown. We investigated eukaryotic recycling using post-TCs assembled on a model mRNA encoding a tetrapeptide followed by a UAA stop codon and report that initiation factors eIF3, eIF1, eIF1A, and eIF3j, a loosely associated subunit of eIF3, can promote recycling of eukaryotic post-TCs. eIF3 is the principal factor that promotes splitting of posttermination ribosomes into 60S subunits and tRNA- and mRNA-bound 40S subunits. Its activity is enhanced by eIFs 3j, 1, and 1A. eIF1 also mediates release of P site tRNA, whereas eIF3j ensures subsequent dissociation of mRNA.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylation
  • Codon, Terminator
  • Peptide Chain Termination, Translational
  • Peptide Elongation Factors / chemistry*
  • Peptide Initiation Factors / chemistry*
  • RNA, Messenger / chemistry*
  • RNA, Transfer / chemistry
  • Ribosomal Proteins / chemistry
  • Ribosome Subunits, Large, Eukaryotic / chemistry
  • Ribosome Subunits, Small, Eukaryotic / chemistry
  • Ribosomes / chemistry*

Substances

  • Codon, Terminator
  • Peptide Elongation Factors
  • Peptide Initiation Factors
  • RNA, Messenger
  • Ribosomal Proteins
  • ribosome releasing factor
  • RNA, Transfer