title: Characterization of the tyramine-producing pathway in Sporolactobacillus sp. P3J.
abstract: A sporulated lactic acid bacterium (LAB) isolated from cider must was shown to harbour the tdc gene encoding tyrosine decarboxylase. The isolate belonged to the Sporolactobacillus genus and may correspond to a novel species. The ability of the tdc-positive strain, Sporolactobacillus sp. strain P3J, to produce tyramine in vitro was demonstrated by using HPLC. A 7535 bp nucleotide sequence harbouring the putative tdc gene was determined. Analysis of the obtained sequence showed that four tyramine production-associated genes [tyrosyl-tRNA synthetase (tyrS), tyrosine decarboxylase (tdc), tyrosine permease (tyrP) and Na(+)/H(+) antiporter (nhaC)] were present and were organized as already described in other tyramine-producing LAB. This operon was surrounded by genes showing the highest identities with mobile elements: a putative phage terminase and a putative transposase (downstream and upstream, respectively), suggesting that the tyramine-forming trait was acquired through horizontal gene transfer. Transcription analyses of the tdc gene cluster suggested that tyrS and nhaC are expressed as monocistronic genes while tdc would be part of a polycistronic mRNA together with tyrP. The presence of tyrosine in the culture medium induced the expression of all genes except for tyrS. A clear correlation was observed between initial tyrosine concentration and tyramine production combined with an increase in the final pH reached by the culture. Finally, cloning and expression of the tyrP gene in Lactococcus lactis demonstrated that its product catalyses the exchange of tyrosine and tyramine.
authors.affiliation: ADRIA Normandie, Boulevard du 13 Juin 1944, 14310 Villers-Bocage, France.
authors.forename: Monika
authors.initials: M
authors.lastname: Coton
authors.affiliation: Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Fernández
authors.affiliation: Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Trip
authors.affiliation: Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain.
authors.forename: Victor
authors.initials: V
authors.lastname: Ladero
authors.affiliation: Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
authors.forename: Niels L
authors.initials: NL
authors.lastname: Mulder
authors.affiliation: Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
authors.forename: Juke S
authors.initials: JS
authors.lastname: Lolkema
authors.affiliation: Instituto de Productos Lácteos de Asturias, CSIC, Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Alvarez
authors.affiliation: ADRIA Normandie, Boulevard du 13 Juin 1944, 14310 Villers-Bocage, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Coton
mesh_terms: D056449:Bacillales / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001628:Beverages / Q000382:microbiology; D003470:Culture Media; D005602:France; D015964:Gene Expression Regulation, Bacterial; D027845:Malus; D008969:Molecular Sequence Data; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014439:Tyramine / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism; D014445:Tyrosine Decarboxylase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D014443:Tyrosine; D014445:Tyrosine Decarboxylase; D014439:Tyramine