An Escherichia coli Chassis for Production of Electrically Conductive Protein Nanowires

Geobacter sulfurreducens' pilin-based electrically conductive protein nanowires (e-PNs) are a revolutionary electronic material. They offer novel options for electronic sensing applications and have the remarkable ability to harvest electrical energy from atmospheric humidity. However, technical constraints limit mass cultivation and genetic manipulation of G. sulfurreducens. Therefore, we designed a strain of Escherichia coli to express e-PNs by introducing a plasmid that contained an inducible operon with E. coli genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PNs. The e-PNs expressed in E. coli and harvested with a simple filtration method had the same diameter (3 nm) and conductance as e-PNs expressed in G. sulfurreducens. These results, coupled with the robustness of E. coli for mass cultivation and the extensive E. coli toolbox for genetic manipulation, greatly expand the opportunities for large-scale fabrication of novel e-PNs.