title: Role of histidine transfer ribonucleic acid in regulation of synthesis of histidyl-transfer ribonucleic acid synthetase of Salmonella typhimurium.
abstract: The role of histidine transfer ribonucleic acid (tRNA) in repression of synthesis of histidyl-tRNA synthetase was examined in two strains of Salmonella typhimurium, one of which was a histidine tRNA (hisR) mutant possessing 52% of the wild-type (hisR(+)) histidine tRNA and a derepressed level of the histidine biosynthetic enzymes during histidine-unrestricted growth. Histidine-restricted growth caused a derepression of the rate of formation of histidyl-tRNA synthetase in both strains. In the case of the wild-type strain, addition of histidine to the derepressed culture caused a repression of synthesis of histidyl-tRNA synthetase for at least one generation of growth. In contrast, when histidine was restored to the derepressed hisR mutant culture, synthesis of histidyl-tRNA synthetase was continued at the initial derepressed rate. These results suggest that histidine must be attached to histidine tRNA for repression of synthesis of histidyl-tRNA synthetase.
mesh_terms: D000332:Aerobiosis; D000604:Amino Acyl-tRNA Synthetases / Q000096:biosynthesis* / Q000378:metabolism; D002247:Carbon Isotopes; D002474:Cell-Free System; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D003470:Culture Media; D004794:Enzyme Repression; D005827:Genetics, Microbial; D006639:Histidine / Q000378:metabolism*; D009154:Mutation; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D012343:RNA, Transfer / Q000302:isolation & purification / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D013053:Spectrophotometry
chemical_list: D002247:Carbon Isotopes; D002712:Chlorides; D003470:Culture Media; D002586:Cesium; D006639:Histidine; D012343:RNA, Transfer; D010744:Phosphoric Monoester Hydrolases; D000604:Amino Acyl-tRNA Synthetases