Surface display of metal binding domain derived from PbrR on Escherichia coli specifically increases lead(II) adsorption
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.
KeywordsBioadsorption Lead Metal binding domain PbrR Surface display
This research was supported by Natural Science Foundation of Guangdong Province (2015A030313838), and Science and Technology Program of Shenzhen (JCYJ20150403091305481).
Supplementary Table 1—Bacterial strains and plasmids used in this study.
Supplementary Fig. 1—Amino acid sequence of Pb2+ binding domain (PbBD) of PbrR and the codon optimized DNA sequence.
Supplementary Fig. 2—The growth curves of E. coli BL21(DE3) harboring pLA, pLAP, and pLAPB.