Surface-engineered Saccharomyces cerevisiae cells displaying redesigned CadR for enhancement of adsorption of cadmium ( II).

BACKGROUND The use of cell-surface display technology to express recombinant proteins on a microbial cell surface can enhance metal adsorption to microbial cells. The transcription factor CadR of Pseudomonas putida shows highly selective affinity with Cd²⁺. RESULTS CadR was genetically engineered by truncating 47 N-terminal amino acids and 21 C-terminal amino acids in order to maximize its expression efficiency while maintaining its metal-binding domain. The redesigned CadR (named T68CadR) was then displayed with Saccharomyces cerevisiae a-agglutinin cell-surface display system. This engineering approach enhanced the H⁺/ OH⁻ buffering capacity and the Cd²⁺ adsorption capacity of yeast cells. The surface-engineered cells also performed well at mesophilic and higher temperatures (30-50 °C) under neutral or alkalescent conditions. With an initial concentration of 1.0 mg L⁻¹, the Cd²⁺ removal efficiency remained 85% when the concentration of Na⁺ changed from 0 to 400 mmol L⁻¹ ( pH 7.8). The surface-engineered cells also showed highly selective adsorption to Cd²⁺ in the presence of Zn²⁺ and Pb²⁺. CONCLUSIONS T68CadR displayed yeast cells constructed in this study provide an option to selectively remove Cd in water. It also might be promising as a tool to determine CadR's Cd-binding mechanism and to improve its selectivity and affinity to Cd²⁺. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]