FIGURE 2.

Genetic organization of the pbr promoter reporter systems. The lead(II) inducible mCherry reporter expression, full-length lacZ reporter expression, and lacZα reporter expression are achieved in E. coli Top10 harboring pPpbr-RFP, pPpbr-lacZ, and pPpbr-lacZα, respectively. Based on a well-known monocistronic reporter cassette, fluorescent signal and enzymatic activity are detected under Pb(II) induction. LacZα and lacZM15 are separately synthesized under the control of target pbr promoter driven by Pb(II), and host lac promoter driven by IPTG. After the active β-galactosidase with a native-like tetramer is finally assembled in vivo, a standard chromogenic substrate method can then be used for qualitative and quantitative determination of β-galactosidase activity.