tRNA-tRNA interactions within cellular ribosomes.
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.
Smith
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D
Department of Molecular, Cellular, University of Colorado, Boulder 80309-0347.
Yarus
M
M
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
D000926:Anticodon; D003062:Codon; D012333:RNA, Messenger; D012343:RNA, Transfer; D001616:beta-Galactosidase