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.
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Acknowledgments
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.
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Tao, HC., Peng, ZW., Li, PS. et al. Optimizing cadmium and mercury specificity of CadR-based E. coli biosensors by redesign of CadR. Biotechnol Lett 35, 1253–1258 (2013). https://doi.org/10.1007/s10529-013-1216-4
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DOI: https://doi.org/10.1007/s10529-013-1216-4