Maintenance of repression control of the ilvGMEDA operon in a temperature-sensitive leucyl-transfer RNA synthetase mutant of Escherichia coli K-12 at a restrictive temperature

Biochem Biophys Res Commun. 1992 Sep 16;187(2):1106-12. doi: 10.1016/0006-291x(92)91311-d.

Abstract

The mechanism of L-leucine regulation of ilvGMEDA is thought to be by ribosome-mediated attenuation that is dependent upon the concentration of Leu-tRNA(Leu) which results from leucyl-tRNA synthetase (LeuRS) activity. The requirement for LeuRS activity in attenuation control was tested in an Escherichia coli K-12 strain containing a temperature-sensitive LeuRS and the ilvGMEDA operon with an active ilvGM. Growth of this strain at 30 degrees C followed by a shift to 37 degrees C to inactivate the LeuRS revealed that ilvGM expression decreased at the restrictive temperature whereas the downstream gene expression was slightly elevated. We suggest that ilvGM does not respond to a deattenuation signal, and that, possibly, a secondary repression/derepression mechanism exists.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Codon
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Gene Expression Regulation, Bacterial*
  • Leucine / genetics
  • Leucine / pharmacology
  • Leucine-tRNA Ligase / chemistry
  • Leucine-tRNA Ligase / genetics*
  • Molecular Sequence Data
  • Mutation*
  • Operon*
  • Protein Sorting Signals / chemistry
  • Protein Sorting Signals / genetics
  • RNA, Transfer, Amino Acyl / metabolism
  • Temperature

Substances

  • Codon
  • Protein Sorting Signals
  • RNA, Transfer, Amino Acyl
  • Leucine-tRNA Ligase
  • Leucine