Generation of a cadmium-binding filamentous phage through cysteine-rich peptide display on PVIII

M13 is a filamentous bacteriophage with a 6 nm thick and 1 mu m length tubular structure. Approximately, 3000 subunits of PVIII, the major coat protein form a cylinder that encapsulates the M13 single-stranded DNA genome. Among capsid proteins sequences, PVIII gene is particularly amenable for the expression of recombinant peptides on the phage surface. It has been identified that thiol rich peptides are able to interact with heavy metals. In this work, we incorporated a heavy metal binding peptide to PVIII producing a viral particle capable of interacting with cadmium. For this purpose, we designed a chimeric gene composed of the coding sequence of a cysteine rich peptide linked to PVIII and cloned into a phagemid vector. Then, we established the optimal conditions for phage production by regulating the expression of the chimeric PVIII protein by using an isopropyl beta-D-1-thiogalactopyranoside (IPTG) inducible system. The cysteine rich recombinant phage interacted with cadmium in a highly efficient manner. Considering this novel property, the recombinant phage produced in this work could be used as a nanotechnology tool in the development of affinity columns, concentration systems for cadmium analysis or bioremediation.