This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hirshfield, I. N. Articles by Buklad, N. E. Search for Related Content PubMed PubMed Citation Articles by Hirshfield, I. N. Articles by Buklad, N. E.

Effect of Alanine, Leucine, and Fructose on Lysyl-Transfer Ribonucleic Acid Ligase Activity in a Mutant of Escherichia coli K-12

¹ The John Collins Warren Laboratories of the Huntington Memorial Hospital of Harvard University at the Massachusetts General Hospital, Boston, Massachusetts 02114

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--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 D₂O 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.

This article has been cited by other articles:

• Brevet, A., Chen, J., Lévque, F., Blanquet, S., Plateau, P. (1995). Comparison of the Enzymatic Properties of the Two Escherichia coli Lysyl-tRNA Synthetase Species. J. Biol. Chem. 270: 14439-14444 [Abstract] [Full Text]