title: Isolation and partial characterization of three Escherichia coli mutants with altered transfer ribonucleic acid methylases.
abstract: Seven transfer ribonucleic acid (tRNA) methylase mutants were isolated from Escherichia coli K-12 by examining the ability of RNA prepared from clones of unselected mutagenized cells to accept methyl groups from S-adenosylmethionine catalyzed by crude enzymes from wild-type cells. Five of the mutants had an altered uracil-tRNA methylase; consequently their tRNA's lacked ribothymidine. One mutant had tRNA deficient in 7-methylguanosine, and one mutant contained tRNA lacking 2-thio-5-methylaminomethyluridine. The genetic loci of the three tRNA methylase mutants were distributed over the E. coli genome. The mutant strain deficient in 7-methylguanosine biosynthesis showed a reduced efficiency in the suppression of amber mutations carried by T4 or lambda phages.
mesh_terms: D002846:Chromatography, Affinity; D002855:Chromatography, Thin Layer; D002874:Chromosome Mapping; D004586:Electrophoresis; D004926:Escherichia coli / Q000201:enzymology* / Q000302:isolation & purification; D005796:Genes; D006151:Guanosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D008780:Methyltransferases / Q000378:metabolism*; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D012329:RNA, Bacterial / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D011995:Recombination, Genetic; D012436:S-Adenosylmethionine / Q000378:metabolism; D013936:Thymidine / Q000031:analogs & derivatives / Q000096:biosynthesis; D014529:Uridine / Q000031:analogs & derivatives / Q000096:biosynthesis
chemical_list: D009153:Mutagens; D009604:Nitrosoguanidines; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D006151:Guanosine; D012436:S-Adenosylmethionine; D012343:RNA, Transfer; D008780:Methyltransferases; D013936:Thymidine; D014529:Uridine