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

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

Results: The PbBD was obtained by truncating the N-terminal DNA-binding domain and C-terminal redundant amino acid residues of the Pb-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 Pb biosorption than that found in PbrR-displayed cells. Specific Pb binding via PbBD was the same as Pb binding via the full-length PbrR, with no observable decline even in the presence of Zn and Cd.

Conclusions: Since surface-engineered E. coli cells with PbBD increased the Pb 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.