title: Recycling of eukaryotic posttermination ribosomal complexes.
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.
authors.affiliation: Department of Microbiology and Immunology, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Pisarev
authors.forename: Christopher U T
authors.initials: CU
authors.lastname: Hellen
authors.forename: Tatyana V
authors.initials: TV
authors.lastname: Pestova
mesh_terms: D000107:Acetylation; D018388:Codon, Terminator; D010443:Peptide Chain Termination, Translational; D010445:Peptide Elongation Factors / Q000737:chemistry*; D010448:Peptide Initiation Factors / Q000737:chemistry*; D012333:RNA, Messenger / Q000737:chemistry*; D012343:RNA, Transfer / Q000737:chemistry; D012269:Ribosomal Proteins / Q000737:chemistry; D054683:Ribosome Subunits, Large, Eukaryotic / Q000737:chemistry; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry; D012270:Ribosomes / Q000737:chemistry*
chemical_list: D018388:Codon, Terminator; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; D012343:RNA, Transfer