title: Effect of Mg2+ concentration, polyamines, streptomycin, and mutations in ribosomal proteins on the accuracy of the two-step selection of aminoacyl-tRNAs in protein biosynthesis.
abstract: Discrimination against the binding of noncognate aminoacyl (aa)-tRNAs by mRNA-programmed ribosomes is the outcome of two selection steps, one involving an aa-tRNA.EFTu.GTP complex, which occurs prior to and includes GTP hydrolysis, the other involving the aa-tRNA alone, which follows GTP hydrolysis. Conditions which lead to errors in protein synthesis have been found to influence the accuracy of one or both selection steps in a system measuring poly(U)-directed binding of Leu-tRNA2Leu. Streptomycin has a large effect only on the discrimination process following GTP hydrolysis, but the other pertubations of recognition studied, high [Mg2+], polyamines, the strA1 and ram1 mutations, affect both discrimination processes. The general result is consistent with the view that proofreading of aa-tRNA by ribosomes for the most part uses the same specificity determinants used in the initial selection of a ternary complex.
mesh_terms: D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D009154:Mutation; D014176:Protein Biosynthesis / Q000187:drug effects*; D011700:Putrescine / Q000494:pharmacology*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D013095:Spermidine / Q000494:pharmacology*; D013307:Streptomycin / Q000494:pharmacology*
chemical_list: D012346:RNA, Transfer, Amino Acyl; D012269:Ribosomal Proteins; D020558:GTP Phosphohydrolases; D008274:Magnesium; D013095:Spermidine; D011700:Putrescine; D013307:Streptomycin