Optimizing cadmium and mercury specificity of CadR-based E. coli biosensors by redesign of CadR
- 907 Downloads
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.
KeywordsCadmium CadR Mercury Specificity Whole cell biosensor
This research was supported by Shenzhen Municipal Government under a grant for Key Lab Construction (CXB201111240110A). We thank Yu-Jie Liang for help in fluorescent assay and Priscilla Young for English language editing.
- Park JN, Sohn MJ, Oh DB, Kwon O, Rhee SK, Hur CG, Lee SY, Gellissen G, Kang HA (2007) Identification of the cadmium-inducible Hansenula polymorpha SEO1 gene promoter by transcriptome analysis and its application to whole-cell heavy-metal detection systems. Appl Environ Microb 73(19):5990–6000CrossRefGoogle Scholar