Fig 4.

Scheme showing the interaction between components of the CitA/CitB and the DcuS/DcuR systems. Interaction (physical or functional) between individual components is indicated by arrows. Physical interaction is derived from FRET and BACTH studies between the proteins (this work) and between the response regulators and target genes (1, 16, 52). Functional interaction was derived from the requirement of the respective component for the expression of citC or dcuB (this work and Krämer et al. [25]). Interrupted lines (gray slashes) indicate that the lack of interaction has been demonstrated either by FRET and BACTH or by expression studies (this work). The physical interaction between CitA and DcuS was derived from BACTH and FRET studies (see Discussion for details).