Multiple input signals, along with protein and RNA elements, regulate the eut locus in Enterococcus faecalis.

A) The organization of the E. faecalis eut locus is shown schematically. The EutV/EutW two component regulatory system responds to ethanolamine to stimulate EutW autophosphorylation followed by phosphoryl transfer to EutV [15], [17]. Phosphorylated EutV is hypothesized to prevent formation of four different intrinsic terminator sites (red) within the eut pathway [17], [18]. Additionally, an AdoCbl-sensing riboswitch is located upstream of eutG [14], [16]. B) Expression of lacZ translational fusions to the eutP 5′ leader region is shown as bar graphs and is described in the text. Each fusion is represented by a color with the darker shade indicating the wild type background and the lighter shade designating the eutVW background. Presence of both AdoCbl and ethanolamine was required for induction of eutP containing the wild-type leader sequence (blue). Deletion of the EutV/EutW two-component regulatory system abolished eutP induction (light blue). Deletion of the terminator in the leader, eutPΔT abolished EutV/EutW dependency (red/light red). The vector control in both backgrounds is shown in black/gray. (C) Expression of lacZ translational fusions to the eutS 5′ leader region. Color scheme is described in the figure.