title: Sulfur-deficient transfer ribonucleic acid in a cysteine-requiring, "relaxed" mutant of Escherichia coli.
abstract: A cysteine-requiring mutant of the parent strain Escherichia coli Hfr Cavalli (RC(rel), Met(-), lambda) has been isolated. The mutant was selected by using replica plating after mutagenesis by N-methyl-N'-nitro-N-nitrosoguanidine. The mutation appears to be in the gene for sulfite reductase, since the mutant could utilize sulfide but not sulfite as a sulfur source. The mutant was found to be RC(rel) with respect to both methionine and cysteine. During cysteine starvation, transfer ribonucleic acid (tRNA) deficient in 4-thiouracil was produced, and in vivo studies indicate that this tRNA can accept sulfur groups to a greater extent than normal tRNA. Further, there were differences both in the rate and extent of amino acid acceptance between normal and sulfur-deficient tRNA. This suggests that thionucleotides are involved in at least one of the biological functions of the tRNA molecule.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis; D002247:Carbon Isotopes; D003545:Cysteine / Q000378:metabolism / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D005827:Genetics, Microbial; D007930:Leucine / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D008967:Molecular Biology; D009154:Mutation; D009711:Nucleotides; D012329:RNA, Bacterial / Q000032:analysis / Q000096:biosynthesis; D012343:RNA, Transfer; D013455:Sulfur; D013460:Sulfur Isotopes; D014316:Tritium; D014498:Uracil / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002247:Carbon Isotopes; D009711:Nucleotides; D012329:RNA, Bacterial; D013460:Sulfur Isotopes; D014316:Tritium; D014498:Uracil; D013455:Sulfur; D012343:RNA, Transfer; D008025:Ligases; D007930:Leucine; D003545:Cysteine