Identification of the Enterococcus faecalis tyrosine decarboxylase operon involved in tyramine production.
Screening of a library of Enterococcus faecalis insertional mutants allowed isolation of a mutant affected in tyramine production. The growth of this mutant was similar to that of the wild-type E. faecalis JH2-2 strain in Maijala broth, whereas high-performance liquid chromatography analyses showed that tyramine production, which reached 1,000 microg ml(-1) for the wild-type strain, was completely abolished. Genetic analysis of the insertion locus revealed a gene encoding a decarboxylase with similarity to eukaryotic tyrosine decarboxylases. Sequence analysis revealed a pyridoxal phosphate binding site, indicating that this enzyme belongs to the family of amino acid decarboxylases using this cofactor. Reverse transcription-PCR analyses demonstrated that the gene (tdc) encoding the putative tyrosine decarboxylase of E. faecalis JH2-2 is cotranscribed with the downstream gene encoding a putative tyrosine-tyramine antiporter and with the upstream tyrosyl-tRNA synthetase gene. This study is the first description of a tyrosine decarboxylase gene in prokaryotes.
Connil
Nathalie
N
Laboratoire de Microbiologie Alimentaire et Industrielle, ENITIAA, rue de la Géraudière, BP82225, 44322 Nantes Cedex 03, France.
Le Breton
Yoann
Y
Dousset
Xavier
X
Auffray
Yanick
Y
Rincé
Alain
A
Prévost
Hervé
H
D000595:Amino Acid Sequence; D013293:Enterococcus faecalis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D012329:RNA, Bacterial / Q000032:analysis; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014439:Tyramine / Q000378:metabolism*; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D012329:RNA, Bacterial; D014445:Tyrosine Decarboxylase; D014439:Tyramine