title: Optimizing cadmium and mercury specificity of CadR-based E. coli biosensors by redesign of CadR.
abstract: The metalloprotein, CadR, was redesigned to optimize cadmium and mercury specificity of CadR-based E. coli biosensors. By truncating 10 and 21 amino acids from the C-terminal extension of CadR, CadR-TC10 and CadR-TC21 were obtained, respectively. The genes cadR, cadR-TC10 and cadR-TC21 were used as sensing elements to construct green fluorescent protein based E.coli biosensors. Induction at 30 °C for 4 h in supplemented M9 medium was the optimized condition for the biosensor. Compared with CadR-based biosensor, there was a clear decline in induction coefficient for CadR-TC21-based biosensor (decreased by 86 % in Zn(II), 44 % in Hg(II), and only 37 % in Cd(II)). While in CadR-TC10-based biosensor, the induction coefficient decreased by 95 % in Zn(II), 70 % in Hg(II), and 67 % in Cd(II). Improved performances of CadR mutants based E. coli biosensors indicated that truncating C-terminal extension of CadR could improve the specificity.
authors.affiliation: Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, 518055, China. taohc@pkusz.edu.cn
authors.forename: Hu-Chun
authors.initials: HC
authors.lastname: Tao
authors.forename: Zhi-Wen
authors.initials: ZW
authors.lastname: Peng
authors.forename: Peng-Song
authors.initials: PS
authors.lastname: Li
authors.forename: Tai-An
authors.initials: TA
authors.lastname: Yu
authors.forename: Jie
authors.initials: J
authors.lastname: Su
mesh_terms: D019677:Artificial Gene Fusion; D015374:Biosensing Techniques / Q000379:methods*; D002104:Cadmium / Q000032:analysis*; D004785:Environmental Pollutants / Q000032:analysis; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008628:Mercury / Q000032:analysis*; D060847:Metabolic Engineering / Q000379:methods; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D004785:Environmental Pollutants; D029968:Escherichia coli Proteins; D014157:Transcription Factors; D002104:Cadmium; D049452:Green Fluorescent Proteins; D008628:Mercury