B Kimura1, H Takahashi, S Hokimoto, Y Tanaka, T Fujii. 1. Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan. kimubo@kaiyodai.ac.jp
Abstract
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.
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.
Authors: Marina Calles-Enríquez; Benjamin Hjort Eriksen; Pia Skov Andersen; Fergal P Rattray; Annette H Johansen; María Fernández; Victor Ladero; Miguel A Alvarez Journal: Appl Environ Microbiol Date: 2010-07-23 Impact factor: 4.792