title: tRNA-tRNA interactions within cellular ribosomes.
abstract: We describe an assay that converts the effects of tRNA-tRNA contacts at two particular codons into a quantitative effect on beta-galactosidase level. The assay measures the separate and combined efficiency of suppression at adjacent nonsense codons in vivo using a set of specially created homologous messages. In a survey of distal anticodon arm substitutions, we find that particular mutant tRNAs occupying the P-site reduce the apparent efficiency of the suppressor tRNA reading the A-site codon by factors of 2-170. By using measured tRNA-tRNA distances and the crystallographic tRNA structure, we propose a model of the tRNA-tRNA-mRNA complex. In the model, the anticodon loops of the P-site and A-site tRNAs contact one another in a way that is consistent with our combined tRNA efficiency data. These results suggest that tRNA-tRNA interactions that modulate tRNA action are an inevitable feature of translation.
authors.affiliation: Department of Molecular, Cellular, University of Colorado, Boulder 80309-0347.
authors.forename: D
authors.initials: D
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Yarus
mesh_terms: D000926:Anticodon / Q000235:genetics; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012333:RNA, Messenger / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012270:Ribosomes / Q000378:metabolism*; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D000926:Anticodon; D003062:Codon; D012333:RNA, Messenger; D012343:RNA, Transfer; D001616:beta-Galactosidase