title: Back to translation: removal of aIF2 from the 5'-end of mRNAs by translation recovery factor in the crenarchaeon Sulfolobus solfataricus.
abstract: The translation initiation factor aIF2 of the crenarchaeon Sulfolobus solfataricus (Sso) recruits initiator tRNA to the ribosome and stabilizes mRNAs by binding via the γ-subunit to their 5'-triphosphate end. It has been hypothesized that the latter occurs predominantly during unfavorable growth conditions, and that aIF2 or aIF2-γ is released on relief of nutrient stress to enable in particular anew translation of leaderless mRNAs. As leaderless mRNAs are prevalent in Sso and aIF2-γ bound to the 5'-end of a leaderless RNA inhibited ribosome binding in vitro, we aimed at elucidating the mechanism underlying aIF2/aIF2-γ recycling from mRNAs. We have identified a protein termed Trf (translation recovery factor) that co-purified with trimeric aIF2 during outgrowth of cells from prolonged stationary phase. Subsequent in vitro studies revealed that Trf triggers the release of trimeric aIF2 from RNA, and that Trf directly interacts with the aIF2-γ subunit. The importance of Trf is further underscored by an impaired protein synthesis during outgrowth from stationary phase in a Sso trf deletion mutant.
authors.affiliation: Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Märtens
authors.forename: Salim
authors.initials: S
authors.lastname: Manoharadas
authors.forename: David
authors.initials: D
authors.lastname: Hasenöhrl
authors.forename: Lukas
authors.initials: L
authors.lastname: Zeichen
authors.forename: Udo
authors.initials: U
authors.lastname: Bläsi
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009154:Mutation; D010442:Peptide Chain Initiation, Translational; D039662:Prokaryotic Initiation Factors / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D048229:Sulfolobus solfataricus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D039662:Prokaryotic Initiation Factors; D012333:RNA, Messenger