title: E. coli initiator tRNA analogs with different nucleotides in the discriminator base position.
abstract: The effect of base changes at the fourth position from the 3'-terminus of Escherichia coli initiator tRNAMet has been studied to test the 'discriminator hypothesis' which proposed that the nucleotide in this position might have a role in the specificity of the aminoacylation reaction. E. coli initiator tRNA lacking the 3'-terminal tetranucleotide was prepared by partial digestion with S1 nuclease. To construct tRNA analogs with different bases in the fourth position this truncated tRNA was joined by RNA ligase to each of four chemically synthesized 2',3'-ethoxy-methylidene tetranucleotides pACCA(em), pCCCA(em), pGCCA(em), and pUCCA(em). In vitro aminoacylation studies showed that all four molecules accepted methionine, albeit with different Vmax values.
mesh_terms: D001483:Base Sequence; D004720:Endonucleases; D004926:Escherichia coli / Q000235:genetics*; D007202:Indicators and Reagents; D009841:Oligonucleotides / Q000138:chemical synthesis*; D009843:Oligoribonucleotides / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D011130:RNA Ligase (ATP); D012346:RNA, Transfer, Amino Acyl / Q000138:chemical synthesis / Q000235:genetics*; D015719:Single-Strand Specific DNA and RNA Endonucleases
chemical_list: D007202:Indicators and Reagents; D009841:Oligonucleotides; D009843:Oligoribonucleotides; D012346:RNA, Transfer, Amino Acyl; C026464:tRNA(m)(Met), methionine-; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases; D011130:RNA Ligase (ATP)