Induction of the histidine decarboxylase genes of Photobacterium damselae subsp. damselae (formally P. histaminum) at low pH

J Appl Microbiol. 2009 Aug;107(2):485-97. doi: 10.1111/j.1365-2672.2009.04223.x. Epub 2009 Mar 16.


Aims: To elucidate the detailed mechanism of histamine production by Photobacterium damselae subsp. damselae.

Methods and results: Histidine decarboxylase and related genes of P. damselae subsp. damselae were cloned, and three open reading frames named as hdcT, hdcA and hisRS were identified. The hdcA gene encodes a polypeptide of 377 amino acids and is considered to be the pyridoxal-P dependent histidine decarboxylase. The hdcT gene is assumed to be a histidine/histamine antiporter, and the hisRS gene is considered to be a histidyl-tRNA synthetase. Recombinant Escherichia coli strains harbouring plasmids carrying the P. damselae hdc genes were shown to over-excrete histamine extracellularly. Northern blot analysis and quantitative RT-PCR revealed high levels of mono- and bi-cistronic transcripts of hdcA, hdcT and hisRS genes under conditions of low pH and histidine excess.

Conclusions: The hdcA gene of P. damselae was constructed as an operon with putative histidine/histamine antiporter and histidyl-tRNA synthetase. Mono- and poly-cistronic transcripts and acid induction were detected.

Significance and impact of the study: This is the first report of cloning the histidine decarboxylase gene cluster in gram-negative bacteria. Also, these genes were induced under acidic conditions and in the presence of excess histidine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / genetics*
  • Cloning, Molecular
  • DNA, Bacterial / analysis*
  • Enzyme Induction
  • Escherichia coli / metabolism
  • Fishes / microbiology
  • Gene Expression Regulation
  • Histidine Decarboxylase / genetics*
  • Histidine Decarboxylase / metabolism
  • Histidine-tRNA Ligase / genetics
  • Hydrogen-Ion Concentration
  • Molecular Sequence Data
  • Open Reading Frames
  • Photobacterium / genetics*
  • Photobacterium / metabolism
  • Pyridoxal Phosphate / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Analysis, DNA


  • Bacterial Proteins
  • DNA, Bacterial
  • Pyridoxal Phosphate
  • Histidine Decarboxylase
  • Histidine-tRNA Ligase