![](https://static.igem.org/mediawiki/2017/6/66/T--Jilin_China--_sec_bg_mr.png)
The function of the composite part we have been working on is to detect and degrade chlorophenol under population control of Geneguard system.
![](https://static.igem.org/mediawiki/2017/4/4d/T--Jilin_China--composite_parts01-01.png)
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.
DmpR is an σ54-dependent transcriptional factor of dmp operon from Pseudomonas sp. Strain CF600[1]. Transcription of Pdmp, promoter of dmp operon, is activated when DmpR detects the presence of certain phenol compounds[1-2]. DmpR directly interacts with proper inducers at its effector-sensing domain, and the effector-sensor compound then binds to Pdmp promoter and downstream transcription is initiated. The DmpR we use is based on the wild type DmpR used by 2013 Peking(BBa_K1031211) but has 5 sites of nucleotides mutation[3](Shows below). The mutant type shows high efficiency of transcription initiation.
![](https://static.igem.org/mediawiki/2017/c/c5/T--Jilin_China--composite_parts02.png)
![](https://static.igem.org/mediawiki/2017/0/0a/T--Jilin_China--composite_parts03.png)
![](https://static.igem.org/mediawiki/2017/5/57/T--Jilin_China--composite_parts04.png)
Figure 2. Mutant type DmpR and wild type DmpR
Toxin CbtA could keep the growth of the engineered bacterium 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[4-5].
![](https://static.igem.org/mediawiki/2017/9/9a/T--Jilin_China--composite_parts05.png)
Figure 3. Reaction of TfdB-JLU
Reference:
[1] V. L. Campos. Detection of Chlorinated Phenols in Kraft Pulp Bleaching Effluents Using DmpR Mutant Strains Bull. Environ. Contam. Toxicol. (2004) 73:666–673
[2] V. L. Campos,1 Monitoring Phenolic Compounds During Biological Treatment of Kraft Pulp Mill Effluent Using Bacterial Biosensors Bull. Environ. Contam. Toxicol. (2006) 77:383–390
[3] ARLENE A. WISE AND CHERYL R. KUSKE*. Generation of Novel Bacterial Regulatory Proteins That Detect Priority Pollutant Phenols. APPLIED AND ENVIRONMENTAL MICROBIOLOGY,0099-2240/00/$04.0010 Jan. 2000, p. 163-169.
[4] 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.
[5] 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