title: Effect of alanine, leucine and fructose on lysyl-transfer ribonucleic acid ligase activity in a mutant of Escherichia coli K-12.
abstract: A mutant of Escherichia coli K-12 was examined which has growth medium-dependent lysyl-transfer ribonucleic acid (tRNA) ligase activity. In minimal medium or 0.5% yeast extract, the activity of the enzyme in the mutant strain was 5 to 10% of wild type. However, when the mutant was grown in a highly enriched medium, such as AC broth (Difco), the activity of the mutant ligase increased 10- to 20-fold. We found that the supplementation of 0.5% yeast extract by l-alanine plus d-fructose replaces the need for the highly enriched medium. Fructose plus l-leucine and fructose plus l-alpha-amino-n-butyric acid were also stimulatory, but not as effective as fructose and alanine. With minimal medium, a combination of carbohydrate (fructose or glucose) plus alanine and leucine was required to replace the enriched medium. The most effective combination was fructose, glucose, alanine, and leucine. Lysyl-tRNA ligase was stimulated 1.5 to 2-fold in the wild-type strain or Hfr H (Hayes) by fructose plus alanine when these strains were cultured in 0.5% yeast extract. Experiments employing the combined technique of density labeling with D(2)O and isopycnic centrifugation in cesium chloride indicated that the increased activity of lysyl-tRNA ligase observed in AC broth or in the presence of fructose, glucose, alanine, and leucine is due to the synthesis of new enzyme.
mesh_terms: D000409:Alanine / Q000494:pharmacology*; D000596:Amino Acids / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002247:Carbon Isotopes; D002474:Cell-Free System; D002499:Centrifugation, Density Gradient; D003470:Culture Media; D003903:Deuterium; D004926:Escherichia coli / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D005632:Fructose / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D007930:Leucine / Q000494:pharmacology*; D008239:Lysine; D009154:Mutation; D013237:Stereoisomerism; D013268:Stimulation, Chemical
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D003470:Culture Media; D005632:Fructose; D003903:Deuterium; D000604:Amino Acyl-tRNA Synthetases; D007930:Leucine; D005947:Glucose; D008239:Lysine; D000409:Alanine