title: Regulation of synthesis of the aminoacyl-transfer ribonucleic acid synthetases for the branched-chain amino acids of Escherichia coli.
abstract: The regulation of synthesis of valyl-, leucyl-, and isoleucyl-transfer ribonucleic acid (tRNA) synthetases was examined in strains of Escherichia coli and Salmonella typhimurium. When valine and isoleucine were limiting growth, the rate of formation of valyl-tRNA synthetase was derepressed about sixfold; addition of these amino acids caused repression of synthesis of this enzyme. The rate of synthesis of the isoleucyl- and leucyl-tRNA synthetases was derepressed only during growth restriction by the cognate amino acid. Restoration of the respective amino acid to these derepressed cultures caused repression of synthesis of the aminoacyl-tRNA synthetase, despite the resumption of the wild-type growth rate.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000032:analysis / Q000096:biosynthesis*; D002247:Carbon Isotopes; D002474:Cell-Free System; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D003470:Culture Media; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D005827:Genetics, Microbial; D007532:Isoleucine / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D013053:Spectrophotometry; D013237:Stereoisomerism; D014633:Valine / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D002712:Chlorides; D003470:Culture Media; D007532:Isoleucine; D002586:Cesium; D000604:Amino Acyl-tRNA Synthetases; D007930:Leucine; D014633:Valine