Construction and characterization of an NaCl-sensitive mutant of Halomonas elongata impaired in ectoine biosynthesis

FEMS Microbiol Lett. 1998 Apr 15;161(2):293-300. doi: 10.1111/j.1574-6968.1998.tb12960.x.


Using transposon mutagenesis we generated a salt-sensitive mutant of the halophilic eubacterium Halomonas elongata impaired in the biosynthesis of the compatible solute ectoine. HPLC determinations of the cytoplasmic solute content showed the accumulation of a biosynthetic precursor of ectoine, L-2,4-diaminobutyric acid. Ectoine and hydroxyectoine were not detectable. This mutant failed to grow in minimal medium with NaCl concentrations exceeding 4%. However, when supplemented with organic osmolytes, the ability to grow in high-salinity medium (15% and higher) was regained. We cloned and sequenced the regions flanking the transposon insertion in the H. elongata chromosome. Sequence comparisons with known proteins revealed significant similarity of the mutated gene to the L-2,4-diaminobutyric acid acetyltransferase from the ectoine biosynthetic pathway in Marinococcus halophilus. Analysis of a PCR product demonstrated that the ectoine biosynthetic genes (ectABC) follow the same order as in M. halophilus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids, Diamino / biosynthesis*
  • Amino Acids, Diamino / genetics
  • Chromatography, High Pressure Liquid
  • DNA Transposable Elements / genetics
  • Genes, Bacterial
  • Gram-Negative Aerobic Rods and Cocci / drug effects
  • Gram-Negative Aerobic Rods and Cocci / genetics
  • Gram-Negative Aerobic Rods and Cocci / growth & development
  • Gram-Negative Aerobic Rods and Cocci / metabolism*
  • Molecular Sequence Data
  • Plasmids / genetics
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Sodium Chloride / pharmacology


  • Amino Acids, Diamino
  • DNA Transposable Elements
  • Sodium Chloride
  • ectoine

Associated data

  • GENBANK/AF031489