Structural Determination of a Filamentous Chaperone to Fabricate Electronically Conductive Metalloprotein Nanowires

Abstract

The transfer of electrons through protein complexes is central to cellular respiration. Exploiting proteins for charge transfer in a controllable fashion has the potential to revolutionize the integration of biological systems and electronic devices. Here we characterize the structure of an ultrastable protein filament and engineer the filament subunits to create electronically conductive nanowires under aqueous conditions. Cryoelectron microscopy was used to resolve the helical structure of gamma-prefoldin, a filamentous protein from a hyperthermophilic archaeon. Conjugation of tetra-heme c3-type cytochromes along the longitudinal axis of the filament created nanowires capable of long-range electron transfer. Electrochemical transport measurements indicated networks of the nanowires capable of conducting current between electrodes at the redox potential of the cytochromes. Functionalization of these highly engineerable nanowires with other molecules, such as redox enzymes, may be useful for bioelectronic applications.

A Protein‐Based Free‐Standing Proton‐Conducting Transparent Elastomer for Large‐Scale Sensing Applications

“…The second important challenge to overcome is the material creation protocol, whereas most known conductive protein‐based polymers use genetically expressed proteins. [ 8,9,12,14–16 ] Although much progress has been made in producing mass amount of genetically expressed proteins, [ 17 ] this is still costly and time‐consuming, even upon upscaling, and cannot result in bulk quantities of highly affordable proteins needed for the large‐scale production of materials. Cost effectiveness is a key requisite of any application, and too often, applications validated at the proof‐of‐concept level in the lab do not undergo upscaling to reach the market, as they were not initially designed to meet the requirements of industrial upscaling through sustainable production (e.g., price of the single components and manufacturing costs).…”

Bioelectrochemistry and the Singularity Point “I Robot”?**

“…The Mavlankar team has recently demonstrated the control of biofilms of G. sulforreducens conductivity through electrode potential bias, this report demonstrates and emphasizes even further both the role of porphyrins in the electrochemical properties of biofilms as well as the ability to manipulate biofilms’ properties and specifically their electrochemical properties using electrodes [37] . Based on these findings in natural pili, artificial pili like structures were designed and have shown conductivity in‐vitro (Figure 1(B)) [38] …”

“…[37] Based on these findings in natural pili, artificial pili like structures were designed and have shown conductivity in-vitro ( Figure 1(B)). [38]…”

“…Adapted with permission from the American Chemical Society, based on reference. [38] Adapted from, [41] which is licensed under a Creative Commons Attribution 4.0 International License.…”

“… (A) bacterial nanowires made of self‐assembled cytochoromes expressed by the electrochemically active Geobacter sulforeducens adapted from Yale University website based on reference; [36] (B) Self‐assembly of filamentous proteins with metalloproteins that allows long range electron transfer. Adapted with permission from the American Chemical Society, based on reference [38] …”