title: Novel E. coli mutants deficient in biosynthesis of 5-methylaminomethyl-2-thiouridine.
abstract: Novel E. coli mutants deficient in biosynthesis of 5- methylaminomethyl -2-thiouridine were isolated based on a phenotype of reduced readthrough at UAG codons. They define 2 new loci trmE and trmF , near 83' on the E. coli map. These mutants are different from strains carrying trmC mutations, which are known to confer a methylation deficiency in biosynthesis of 5- methylaminomethyl -2-thiouridine. tRNA from mutants carrying trmE or trmF mutations was shown to carry 2-thiouridine instead of 5- methylaminomethyl -2-thiouridine. This deficiency affects the triplet binding properties of the mutant tRNA. Our results suggest that the 5- methylaminomethyl group stabilizes the basepairing of this modified nucleotide with G, most likely through direct interaction with the ribosomal binding site(s).
mesh_terms: D001483:Base Sequence; D003062:Codon; D004926:Escherichia coli / Q000235:genetics*; D005838:Genotype; D009154:Mutation; D010641:Phenotype; D012343:RNA, Transfer / Q000235:genetics*; D013045:Species Specificity; D013891:Thiouridine / Q000031:analogs & derivatives* / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D003062:Codon; D013891:Thiouridine; C011916:5-methylaminomethyl-2-thiouridine; D012343:RNA, Transfer; D001616:beta-Galactosidase