The function of the composite part we have been working on is to detect and degrade chlorophenol under population control of Geneguard system.
Figure 1: The TA - DmpR - TfdB-JLU construct
This part is a combination of our Geneguard system and chlorophenol response system. Part BBa_J23107 is a constitutive promoter which could provide a constitutive expression of sensor DmpR and toxin CbtA.
This DmpR in our device is a mutant type based on the wild type DmpR used by 2013 Peking(BBa_K1031211) and showed more efficient and wider substrate range than wild type.
Toxin CbtA could keep the growth of the engineered bacteria in a low level. When exposed to contaminants, complex of DmpR and chlorophenol could bind to promoter Po and initiate the expression of antitoxin CbeA as well as TfdB-JLU, a monooxygenase that is responsible for initial hydroxylation of the benzene ring[1-2].
Figure 3. Reaction of TfdB-JLU
 Ledger T, Pieper DH, Gonzalez B. (2006) Chlorophenol hydroxylases encoded by plasmid pJP4 differentially contribute to chlorophenoxyacetic acid degradation. Appl Environ Microbiol 72:2783–2792.
 Yang Lu. (2011) Cloning and characterisation of a novel 2,4-dichlorophenol hydroxylase from a metagenomic library derived from polychlorinated biphenyl-contaminated soil. Biotechnol Lett. 33:1159–1167