title: TRNA2Gln Su+2 mutants that increase amber suppression.
abstract: We selected mutants of lambda pSu+2 which had an increased ability to suppress on Escherichia coli trp B9601 amber mutation on translationally stringent rpsL594 streptomycin-resistant ribosomes. tRNA2Gin Su+2 molecules produced from eight independent mutants were purified, and their ribonucleic acid sequences were determined. Two types of mutations were mapped to the tRNA2Gin Su+2(glnV) gene by this method. Both altered the pseudouridine at position 37 of the tRNA anticodon loop. Seven of the isolates were transitions (pseudouridine to cytosine), and one was a transversion (pseudouridine to adenine). These mutations resulted in Su+ transfer ribonucleic acid molecules that exhibited higher transmission coefficients than their parent Su+2 transfer ribonucleic acids. As judged by their suppressor spectra on T4 amber mutants, which were almost identical to that of Su+2, the two mutant Su+ transfer ribonucleic acids inserted glutamine at amber sites.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics; D005973:Glutamine; D009154:Mutation; D012343:RNA, Transfer / Q000235:genetics*; D013379:Substrate Specificity; D013489:Suppression, Genetic
chemical_list: D005973:Glutamine; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases