Transcriptional regulation of agmatine deiminase pathway in Enterococcus faecalis

ESPARIZ MARTÍN, BLANCATO VICTOR, AND MAGNI CHRISTIANAREZ ET AL

Potrero de los Funes

Congreso; XLV Reunión Anual de SAIB; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Enterococcus faecalis are found as nonstarter lactic acid bacteria in a wide variety of cheeses mostly produced from raw milk. This microorganism can be potentially hazardous to human health due to their pathogenicity or by the production of toxic compounds like biogenic amines. E. faecalis is able to metabolize agmatine with putrescine, ammonia and ATP as final products, by means of agmatine deiminase pathway. In this work we demonstrate that the transcriptional regulator AguR is essential for the agmatine metabolism in E. faecalis, since an AguR defective strain is unable to grow in presence of agmatine. Moreover, as a result of â-galactosidase and Northern blot analysis we could demonstrate that agmatine is inducing the agu gene cluster. There are some differences in the mechanisms underlying agmatine metabolizing gene expression in E. faecalis with the related bacterium Streptococcus mutants. In the later the agu cluster is induced under acid or high temperature conditions, whereas in E. faecalis its expression showed to be independent of pH and temperature. Finally, we investigated the role of catabolite repression on the activity of the AguR controlled promoter, showing that this promoter is regulated by a CcpA independent mechanism.