title: Isolation and partial characterization of temperature-sensitive Escherichia coli mutants with altered leucyl- and seryl-transfer ribonucleic acid synthetases.
abstract: Two temperature-sensitive mutants of Escherichia coli have been found in which the conditional growth is a result of a thermosensitive leucyl-transfer ribonucleic acid (tRNA) synthetase and seryl-tRNA synthetase, respectively. The corresponding genetic loci, leuS and serS, cotransduce with lip and serC, respectively. As a result of the mutationally altered leucyl-tRNA synthetase, some leucine-, valine-, and isoleucine-forming enzymes were derepressed. Thus, leucyl-tRNA synthetase is involved in the repression of the enzymes needed for the synthesis of branched-chain amino acids.
mesh_terms: D000215:Acylation; D000596:Amino Acids / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D002247:Carbon Isotopes; D002474:Cell-Free System; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D003470:Culture Media; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D005827:Genetics, Microbial; D007106:Immune Sera; D007532:Isoleucine / Q000096:biosynthesis; D007930:Leucine / Q000096:biosynthesis; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D012694:Serine; D013696:Temperature; D014161:Transduction, Genetic; D014633:Valine / Q000096:biosynthesis
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D003470:Culture Media; D007106:Immune Sera; D009153:Mutagens; D009604:Nitrosoguanidines; D007532:Isoleucine; D012694:Serine; D000604:Amino Acyl-tRNA Synthetases; D007930:Leucine; D014633:Valine