초록
<P><B>Background</B></P><P>Scientific interest in <I>Enterococcus faecalis</I> has increased greatly over recent decades. Some strains are involved in food fermentation and offer health benefits, whereas others are vancomycin-resistant and cause infections that are difficult to treat. The limited availability of vectors able to express cloned genes efficiently in <I>E. faecalis</I> has hindered biotechnological studies on the bacterium’s regulatory and pathogenicity-related genes. The agmatine deiminase (AGDI) pathway of <I>E. faecalis</I>, involved in the conversion of agmatine into putrescine, is driven by a response inducer gene <I>aguR</I>.</P><P><B>Results</B></P><P>This study describes that the exposure to the induction factor (agmatine) results in the transcription of genes under the control of the <I>aguB</I> promoter, including the <I>aguBDAC</I> operon. A novel <I>E. faecalis</I> expression vector, named pAGEnt, combining the <I>aguR</I> inducer gene and the <I>aguB</I> promoter followed by a cloning site and a stop codon was constructed. pAGEnt was designed for the overexpression and purification of a protein fused to a 10-amino-acid His-tag at the C-terminus. The use of GFP as a reporter of gene expression in <I>E. faecalis</I> revealed that under induction with 60 mM agmatine, fluorescence reached 40 arbitrary units compared to 0 in uninduced cells.</P><P><B>Conclusion</B></P><P>pAGEnt vector can be used for the overexpression of recombinant proteins under the induction of agmatine in <I>E. faecalis,</I> with a close correlation between agmatine concentration and fluorescence when GFP was used as reporter.</P>