title: Identification of specific Rp-phosphate oxygens in the tRNA anticodon loop required for ribosomal P-site binding.
abstract: tRNA binding to the ribosomal P site is dependent not only on correct codon-anticodon interaction but also involves identification of structural elements of tRNA by the ribosome. By using a phosphorothioate substitution-interference approach, we identified specific nonbridging Rp-phosphate oxygens in the anticodon loop of tRNA(Phe) from Escherichia coli which are required for P-site binding. Stereospecific involvement of phosphate oxygens at these positions was confirmed by using synthetic anticodon arm analogues at which single Rp- or Sp-phosphorothioates were incorporated. Identical interference results with yeast tRNA(Phe) and E. coli tRNA(fMet) indicate a common backbone conformation or common recognition elements in the anticodon loop of tRNAs. N-ethyl-N-nitrosourea modification-interference experiments with natural tRNAs point to the importance of the same phosphates in the loop. Guided by the crystal structure of tRNA(Phe), we propose that specific Rp-phosphate oxygens are required for anticodon loop ("U-turn") stabilization or are involved in interactions with the ribosome on correct tRNA-mRNA complex formation.
authors.affiliation: Institute of Microbiology and Genetics, University of Vienna, Austria.
authors.forename: W
authors.initials: W
authors.lastname: Schnitzer
authors.forename: U
authors.initials: U
authors.lastname: von Ahsen
mesh_terms: D000926:Anticodon; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D005038:Ethylnitrosourea / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism*; D012358:RNA, Transfer, Met / Q000737:chemistry / Q000235:genetics*; D012360:RNA, Transfer, Phe / Q000737:chemistry / Q000235:genetics*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013873:Thionucleotides / Q000378:metabolism
chemical_list: D000926:Anticodon; D012358:RNA, Transfer, Met; D012360:RNA, Transfer, Phe; D012269:Ribosomal Proteins; D013873:Thionucleotides; D005038:Ethylnitrosourea; D010100:Oxygen