Surface display of metal binding domain derived from PbrR on Escherichia coli specifically increases lead(II)...

To improve the Pb²⁺ biosorption capacity of the potential E. coli biosorbent, a putative Pb²⁺ binding domain (PbBD) derived from PbrR was efficiently displayed on to the E. coli cell surface.

The PbBD was obtained by truncating the N-terminal DNA-binding domain and C-terminal redundant amino acid residues of the Pb²⁺-sensing transcriptional factor PbrR. Whole-cell sorbents were constructed with the full-length PbrR and PbBD of PbrR genetically engineered onto the surface of E. coli cells using Lpp-OmpA as the anchor. Followed by a 1.71-fold higher display of PbBD than PbrR, the presence of PbBD on the surface of E. coli cells enabled a 1.92-fold higher Pb²⁺ biosorption than that found in PbrR-displayed cells. Specific Pb²⁺ binding via PbBD was the same as Pb²⁺ binding via the full-length PbrR, with no observable decline even in the presence of Zn²⁺ and Cd²⁺.

Since surface-engineered E. coli cells with PbBD increased the Pb²⁺ binding capacity and did not affect the adsorption selectivity, this suggests that surface display of the metal binding domain derived from MerR-like proteins may be used for the bioremediation of specific toxic heavy metals.