Fig. 3: TrcR is an autorepressor as shown with microscopic images of CFP reporter fluorescence.

a A plasmid bearing a CFP reporter gene under the control of the trcR promoter (ptrcRCFP) in WT, M20 and ΔtrcR backgrounds. b WT or ΔtrcR bearing a replicative plasmid with the expression of TrcR driven by an inducible system (the CT promoter, PCT), together with ptrcRCFP as in (a). No inducers were added, thus no induction of TrcR from the plasmid. ΔtrcR::ptrcRCFP as in A was used as a control. c Same experiments performed as in (b) but with addition of inducers (0.6 μM Cu2+ + 2 mM Tp) in the growth medium for the expression of trcR from the inducible promoter PCT, and CFP expressed from the promoter of trcR (ptrcRCFP).