AUTHOR=Perez Marta , Ladero Victor , del Rio Beatriz , Redruello Begoña , de Jong Anne , Kuipers Oscar , Kok Jan , Martin M. Cruz , Fernandez Maria , Alvarez Miguel A. 

TITLE=The Relationship among Tyrosine Decarboxylase and Agmatine Deiminase Pathways in Enterococcus faecalis

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.02107

DOI=10.3389/fmicb.2017.02107

ISSN=1664-302X

ABSTRACT=<p>Enterococci are considered mainly responsible for the undesirable accumulation of the biogenic amines tyramine and putrescine in cheeses. The biosynthesis of tyramine and putrescine has been described as a species trait in <italic>Enterococcus faecalis.</italic> Tyramine is formed by the decarboxylation of the amino acid tyrosine, by the tyrosine decarboxylase (TDC) route encoded in the <italic>tdc</italic> cluster. Putrescine is formed from agmatine by the agmatine deiminase (AGDI) pathway encoded in the <italic>agdi</italic> cluster. These biosynthesis routes have been independently studied, tyrosine and agmatine transcriptionally regulate the <italic>tdc</italic> and <italic>agdi</italic> clusters. The objective of the present work is to study the possible co-regulation among TDC and AGDI pathways in <italic>E. faecalis</italic>. In the presence of agmatine, a <italic>positive</italic> correlation between putrescine biosynthesis and the tyrosine concentration was found. Transcriptome studies showed that tyrosine induces the transcription of putrescine biosynthesis genes and up-regulates pathways involved in cell growth. The tyrosine modulation over AGDI route was not observed in the mutant Δ<italic>tdc</italic> strain. Fluorescence analyses using <italic>gfp</italic> as reporter protein revealed P<italic>aguB</italic> (the promoter of <italic>agdi</italic> catabolic genes) was induced by tyrosine in the wild-type but not in the mutant strain, confirming that <italic>tdc</italic> cluster was involved in the tyrosine induction of putrescine biosynthesis. This study also suggests that AguR (the transcriptional regulator of <italic>agdi</italic>) was implicated in interaction among the two clusters.</p>