(604e) Optimizing the Production of a Blue-Absorbing Proteorhodopsin for the Construction of a Multi Wavelength Biological Photodetector

Living systems routinely rely on proton gradients to control complex functions such as energy production, bioluminescence and propulsion. These processes have been a rich source of inspiration in the burgeoning field of bioelectronics where biological components are integrated with electronic devices to harness novel functionalities or achieve a seamless interface with biology. Here, we report on the fabrication and testing of a bioprotonic device that responds to different wavelengths of light by producing electronic currents of varying intensities. The device is based on the use of two retinal-containing transmembrane proteins that transport protons across lipid bilayers in response to illumination with green (H. turkmenica deltarhodopsin, HtdR) or blue light (proteorhodopsin; PR). We were able to achieve high-level production of a homogeneous variant of PR by precluding the cleavage of a signal sequence that improves the biogenesis of the protein in the E. coli inner membrane but whose removal is both inefficient and not required for function. We further found that proton-pumping activity was maintained upon fusion of the Pd4 palladium-binding peptide to the N-terminus of the full-length PR variant. By integrating Pd4-PR and Pd4-HtdR within supported lipid bilayers and forming an intimate contact with a palladium “protode” through the Pd4 segments we were able to demonstrate wavelength dependent conversion of protonic currents into electronic signals, opening the door to the construction of biologically inspired photodetectors.