Decorating Microbially Produced Protein Nanowires with Peptide Ligands

Abstract

The potential applications of electrically conductive protein nanowires (e-PNs) harvested from Geobacter sulfurreducens might be greatly expanded if the outer surface of the wires could be modified to confer novel sensing capabilities or to enhance binding to other materials. We developed a simple strategy for functionalizing e-PNs with surface-exposed peptide ligands. The G. sulfurreducens gene for the monomer that assembles into e-PNs was modified to add known peptide ligands at the carboxyl terminus of the monomer. Strains of G. sulfurreducens were constructed that fabricated synthetic e-PNs with a six-histidine His-tag or both the His-tag and a nine-peptide HA-tag exposed on the outer surface. Addition of the peptide ligands did not diminish e-PN conductivity. The abundance of HA-tag in e-PNs was controlled by placing expression of the gene for the synthetic monomer with the HA-tag under transcriptional regulation. These studies suggest broad possibilities for tailoring e-PN properties for diverse applications.