title: Splitting of the posttermination ribosome into subunits by the concerted action of RRF and EF-G.
abstract: After peptide release by a class-1 release factor, the ribosomal subunits must be recycled back to initiation. We have demonstrated that the distance between a strong Shine-Dalgarno (SD) sequence and a codon in the P site is crucial for the binding stability of the deacylated tRNA in the P site of the posttermination ribosome and the in-frame maintenance of its mRNA. We show that the elongation factor EF-G and the ribosomal recycling factor RRF split the ribosome into subunits in the absence of initiation factor 3 (IF3) by a mechanism that requires both GTP and GTP hydrolysis. Taking into account that EF-G in the GTP form and RRF bind with positive cooperativity to the free 50S subunit but with negative cooperativity to the 70S ribosome, we suggest a mechanism for ribosome recycling that specifies distinct roles for EF-G, RRF, and IF3.
authors.affiliation: Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Sweden.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Zavialov
authors.forename: Vasili V
authors.initials: VV
authors.lastname: Hauryliuk
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
mesh_terms: D001483:Base Sequence; D007700:Kinetics; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; D012343:RNA, Transfer