Multi-heme cytochromes (MHCs) are fascinating proteins used by bacterial organisms to shuttle electrons within, between, and out of their cells. When placed in solid-state electronic junctions, MHCs support temperature-independent currents over several nanometers that are 3 orders of magnitude higher compared to other redox proteins of similar size. To gain molecular-level insight into their astonishingly high conductivities, we combine experimental photoemission spectroscopy with DFT+Σ current-voltage calculations on a representative Gold-MHC-Gold junction. We find that conduction across the dry, 3 nm long protein occurs via off-resonant coherent tunneling, mediated by a large number of protein valence-band orbitals that are strongly delocalized over heme and protein residues. This picture is profoundly different from the electron hopping mechanism induced electrochemically or photochemically under aqueous conditions. Our results imply that the current output in solid-state junctions can be even further increased in resonance, for example, by applying a gate voltage, thus allowing a quantum jump for next-generation bionanoelectronic devices.

Department of Immunology Weizmann Institute of Science Rehovot Israel

Department of Materials and Interfaces Weizmann Institute of Science Rehovot Israel

Department of Organic Chemistry Weizmann Institute of Science Rehovot Israel

Department of Physics and Astronomy University College London Gower Street London WC1E 6BT U K

Faculty of Science University of South Bohemia Branisovska 1760 370 05 Ceske Budejovice Czech Republic

Graduate School of Science and Engineering Chiba University Chiba Japan

School of Chemistry School of Biological Sciences University of East Anglia Norwich Research Park Norwich NR4 7TJ U K

Zobrazit více v PubMed

Jiang X.; van Wonderen J. H.; Butt J. N.; Edwards M. J.; Clarke T. A.; Blumberger J. Which Multi-Heme Protein Complex Transfers Electrons More Efficiently? Comparing MtrCAB from Shewanella with OmcS from Geobacter. J. Phys. Chem. Lett. 2020, 9421.10.1021/acs.jpclett.0c02842. PubMed DOI

Chong G. W.; Karbelkar A. A.; El-Naggar M. Y. Nature’s Conductors: What Can Microbial Multi-Heme Cytochromes Teach Us About Electron Transport and Biological Energy Conversion?. Curr. Opin. Chem. Biol. 2018, 47, 7–17. 10.1016/j.cbpa.2018.06.007. PubMed DOI

Blumberger J. Electron Transfer and Transport through Multi-Heme Proteins: Recent Progress and Future Directions. Curr. Opin. Chem. Biol. 2018, 47, 24–31. 10.1016/j.cbpa.2018.06.021. PubMed DOI

Paixao V. B.; Salgueiro C. A.; Brennan L.; Reid G. A.; Chapman S. K.; Turner D. L. The Solution Structure of a Tetraheme Cytochrome from Shewanella frigidimarina Reveals a Novel Family Structural Motif. Biochemistry 2008, 47, 11973–11980. 10.1021/bi801326j. PubMed DOI

Clarke T. A.; Edwards M. J.; Gates A. J.; Hall A.; White G. F.; Bradley J.; Reardon C. L.; Shi L.; Beliaev A. S.; Marshall M. J.; et al. Structure of a Bacterial Cell Surface Decaheme Electron Conduit. Proc. Natl. Acad. Sci. U. S. A. 2011, 108, 9384–9389. 10.1073/pnas.1017200108. PubMed DOI PMC

Edwards M. J.; Hall A.; Shi L.; Fredrickson J.; Zachara J. M.; Butt J. N.; Richardson D. J.; Clarke T. A. The Crystal Structure of the Extracellular 11-Heme Cytochrome UndA Reveals a Conserved 10-Heme Motif and Defined Binding Site for Soluble Iron Chelates. Structure 2012, 20, 1275–1284. 10.1016/j.str.2012.04.016. PubMed DOI

Edwards M. J.; White G. F.; Norman M.; Tome-Fernandez A.; Ainsworth E.; Shi L.; Fredrickson J. K.; Zachara J. M.; Butt J. N.; Richardson D. J.; Clarke T. A. Extracellular Decaheme Proteins Involved in Microbe-Mineral Electron Transfer. Sci. Rep. 2015, 5, 11677.10.1038/srep11677. PubMed DOI PMC

Edwards M. J.; White G. F.; Butt J. N.; Richardson D. J.; Clarke T. A. The Crystal Structure of a Biological Insulated Transmembrane Molecular Wire. Cell 2020, 181, 1–9. 10.1016/j.cell.2020.03.032. PubMed DOI PMC

Wang F.; Gu Y.; O’Brien J. P.; Yi M. S.; Yalcin S. E.; Srikanth V.; Shen C.; Vu D.; Ing N. L.; Hochbaum A. I.; et al. Structure of Microbial Nanowires Reveals Stacked Hemes that Transport Electrons over Micrometers. Cell 2019, 177, 361–369. 10.1016/j.cell.2019.03.029. PubMed DOI PMC

Filman D. J.; Marino S. F.; Ward J. E.; Yang L.; Mester Z.; Bullitt E.; Lovley D. R.; Strauss M. Cryo-EM Reveals the Structural Basis of Long-Range Electron Transport in a Cytochrome-based Bacterial Nanowire. Commun. Biol. 2019, 2, 219.10.1038/s42003-019-0448-9. PubMed DOI PMC

van Wonderen J. H.; Hall C. R.; Jiang X.; Adamczyk K.; Carof A.; Heisler I.; Piper S. E. H.; Clarke T. A.; Watmough N. J.; Sazanovich I. V.; et al. Ultrafast Light-Driven Electron Transfer in a Ru(II)tris(bipyridine)-Labeled Multiheme Cytochrome. J. Am. Chem. Soc. 2019, 141, 15190–15200. 10.1021/jacs.9b06858. PubMed DOI

van Wonderen J. H.; Li D.; Piper S. E. H.; Lau C. Y.; Jenner L. P.; Hall C. R.; Clarke T. A.; Watmough N. J.; Butt J. N. Photosensitised Multiheme Cytochromes as Light-Driven Molecular Wires and Resistors. ChemBioChem 2018, 19, 2206–2215. 10.1002/cbic.201800313. PubMed DOI

Polizzi N. F.; Skourtis S. S.; Beratan D. N. Physical Constraints on Charge Transport through Bacterial Nanowires. Faraday Discuss. 2012, 155, 43–62. 10.1039/C1FD00098E. PubMed DOI PMC

Jiang X.; Burger B.; Gajdos F.; Bortolotti C.; Futera Z.; Breuer M.; Blumberger J. Kinetics of Trifurcated Electron Frlow in the Decaheme Bacterial Proteins MtrC and MtrF. Proc. Natl. Acad. Sci. U. S. A. 2019, 116, 3425–3430. 10.1073/pnas.1818003116. PubMed DOI PMC

Jiang X.; Futera Z.; Ali M. E.; Gajdos F.; von Rudorff G. F.; Carof A.; Breuer M.; Blumberger J. Cysteine Linkages Accelerate Electron Flow through Tetra-Heme Protein STC. J. Am. Chem. Soc. 2017, 139, 17237–17240. 10.1021/jacs.7b08831. PubMed DOI

Breuer M.; Rosso K. M.; Blumberger J. Electron Flow in Multiheme Bacterial Cytochromes is a Balancing Act Between Heme Electroonic Interaction and Redox Potentials. Proc. Natl. Acad. Sci. U. S. A. 2014, 111, 611–616. 10.1073/pnas.1316156111. PubMed DOI PMC

Breuer M.; Zarzycki P.; Shi L.; Clarke T. A.; Edwards M. J.; Butt J. N.; Richardson D. J.; Fredrickson J. K.; Zachara J. M.; Blumberger J.; Rosso K. M. Molecular Structure and Free Energy Landscape for Electron Transport in the Decahaem Cytochrome MtrF. Biochem. Soc. Trans. 2012, 40, 1198–1203. 10.1042/BST20120139. PubMed DOI

Blumberger J. Recent Advances in the Theory and Molecular Simulation of Biological Electron Transfer Reactions. Chem. Rev. 2015, 115, 11191–11238. 10.1021/acs.chemrev.5b00298. PubMed DOI

Szczesny J.; Markovic N.; Conzuelo F.; Zacarias S.; Pereira I. A. C.; Lubitz W.; Plumere N.; Schuhmann W.; Ruff A. A Gas Breathing Hydrogen/Air Biofuell Cell Comprising a Redox Polymer/Hydrogenase-Based Bionanode. Nat. Commun. 2018, 9, 4715.10.1038/s41467-018-07137-6. PubMed DOI PMC

Bostick C. D.; Mukhopadhyay S.; Pecht I.; Sheves M.; Cahen D.; Lederman D. Protein Bioelectronics: A Review of What We Do and Do Not Know. Rep. Prog. Phys. 2018, 81, 026601.10.1088/1361-6633/aa85f2. PubMed DOI

Wu J.; Lan Z.; Lin J.; Huang M.; Hao S.; Sato T.; Yin S. A Novel Thermosetting Gel Electrolyte for Stable Quasi-Solid-State Dye-Sensitized Solar Cells. Adv. Mater. 2007, 19, 4006–4011. 10.1002/adma.200602886. DOI

Garg K.; Ghosh M.; Eliash T.; van Wonderen J. H.; Butt J. N.; Shi L.; Jiang X.; Zdenek F.; Blumberger J.; Pecht I.; Sheves M.; Cahen D. Direct Evidence for Heme-Assisted Solid-State Electronic Conduction in Multi-Heme c-Type Cytochromes. Chem. Sci. 2018, 9, 7304–7310. 10.1039/C8SC01716F. PubMed DOI PMC

Sepunaru L.; Pecht I.; Sheves M.; Cahen D. Solid-State Electron Transport across Azurin: From a Temperature-Independent to a Temperature-Activated Mechanism. J. Am. Chem. Soc. 2011, 133, 2421–2423. 10.1021/ja109989f. PubMed DOI

Byun H. S.; Pirbadian S.; Nakano A.; Shi L.; El-Naggar M. Y. Kinetic Monte Carlo Simulations and Molecular Conductance Measurements of the Bacterial Decaheme Cytochrome MtrF. ChemElectroChem. 2014, 1, 1932–1939. 10.1002/celc.201402211. DOI

Wigginton N. S.; Rosso K. M.; Lower B. H.; Shi L.; Hochella M. F. J. Electron Tunnling Properties of Outer-Membrane Decaheme Cytochromes from Shewanella oneidensis. Geochim. Cosmochim. Acta 2007, 71, 543–555. 10.1016/j.gca.2006.10.002. DOI

Wigginton N. S.; Rosso K. M.; Hochella M. F. J. Mechanism of Electron Transifer in Two Decaheme Cytochromes from a Metal-Reducing Bacterium. J. Phys. Chem. B 2007, 111, 12857–12864. 10.1021/jp0718698. PubMed DOI

Pirbadian S.; El-Naggar M. Y. Multistep Hopping and Extracellular Charge Transfer in Microbial Redox Chains. Phys. Chem. Chem. Phys. 2012, 14, 13802–13808. 10.1039/c2cp41185g. PubMed DOI

Futera Z.; Blumberger J. Electronic Couplings for Charge Transfer across Molecule/Metal and Molecule/Semiconductor Interfaces: Performance of the Projector Operator-Based Diabatization Approach. J. Phys. Chem. C 2017, 121, 19677–19689. 10.1021/acs.jpcc.7b06566. DOI

Marcus R. A.; Sutin N. Electron Transfer in Chemistry and Biology. Biochim. Biophys. Acta, Rev. Bioenerg. 1985, 811, 265–322. 10.1016/0304-4173(85)90014-X. DOI

Chidsey C. E. D. Free Energy and Temperature Dependence of Electron Transfer at the Metal-electrolyte Interface. Science 1991, 251, 919–922. 10.1126/science.251.4996.919. PubMed DOI

Simmons J. G. Generalized Formula for the Electric Tunnel Effect between Similar Electrodes Separated by a Thin Insulating Film. J. Appl. Phys. 1963, 34, 1793–1803. 10.1063/1.1702682. DOI

Carey R.; Chen L.; Gu B.; Franco I. When Can Time-Dependent Currents Be Reproduced by the Landauer Steady-State Approximation?. J. Chem. Phys. 2017, 146, 174101.10.1063/1.4981915. PubMed DOI

Nitzan A.Chemical Dynamics in Condensed Phases: Relaxation, Transfer, and Reactions in Condensed Molecular Systems; Oxford University Press, 2006.

Valianti S.; Cuevas J.-C.; Skourtis S. S. Charge-Transport Mechanism in Azurin-Based Monolayer Junctions. J. Phys. Chem. C 2019, 123, 5907.10.1021/acs.jpcc.9b00135. DOI

Iori F.; Di Felice R.; Molinari E.; Corni S. GoIP: An Atomistic Force-Field to Describe the Interaction of Proteins With Au(111) Surfaces in Water. J. Comput. Chem. 2009, 30, 1465–1476. 10.1002/jcc.21165. PubMed DOI

Wright L. B.; Rodger P. M.; Corni S.; Walsh T. R. GoIP-CHARMM: First-Principles Based Force Fields for the Interaction of Proteins with Au(111) and Au(100). J. Chem. Theory Comput. 2013, 9, 1616–1630. 10.1021/ct301018m. PubMed DOI

Futera Z.; Blumberger J. Adsorption of Amino Acids on Gold: Assessing the Accuracy of the GolP-CHARMM Force Field and Parametrization of Au-S Bonds. J. Chem. Theory Comput. 2019, 15, 613–624. 10.1021/acs.jctc.8b00992. PubMed DOI

Ollila O. H. S.; Risselada H. J.; Louhivuori M.; Lindahl E.; Vattulainen I.; Marrink S. J. 3D Pressure Field in Lipipd Membranes and Membrane-Protein Complexes. Phys. Rev. Lett. 2009, 102, 78101.10.1103/PhysRevLett.102.078101. PubMed DOI

Hutter J.; Iannuzzi M.; Schiffmann F.; VandeVondele J. CP2K: Atomistic Simulations of Condensed Matter Systems. WIREs Comput. Mol. Sci. 2014, 4, 15–25. 10.1002/wcms.1159. DOI

Goedecker S.; Teter M.; Hutter J. Separable Dual-Space Gaussian Pseudopotential. Phys. Rev. B: Condens. Matter Mater. Phys. 1996, 54, 1703–1710. 10.1103/PhysRevB.54.1703. PubMed DOI

Perdew J. P.; Burke K.; Ernzerhof M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865–3868. 10.1103/PhysRevLett.77.3865. PubMed DOI

Neaton J. B.; Hybertsen M. S.; Louie S. G. Renormalization of Molecular Electronic Levels at Metal-Molecule Intefaces. Phys. Rev. Lett. 2006, 97, 216405.10.1103/PhysRevLett.97.216405. PubMed DOI

Darancet P.; Widawsky J. R.; Choi H. J.; Venkataraman L.; Neaton J. B. Quantitative Current-Voltage Characteristics in Molecular Junctions from First Principles. Nano Lett. 2012, 12, 6250–6254. 10.1021/nl3033137. PubMed DOI

Egger D. A.; Liu Z.-F.; Neaton J. B.; Kronik L. Reliable Energy Level Alignment at Physisorbed Molecule-Metal Interfaces from Density Functional Theory. Nano Lett. 2015, 15, 2448–2455. 10.1021/nl504863r. PubMed DOI PMC

Liu Z.-F.; Egger D. A.; Refaely-Abramson S.; Kronik L.; Neaton J. B. Energy Level Alignment at Molecule-Metal Interfaces from an Optimally Tuned Range Separated Hybrid Functional. J. Chem. Phys. 2017, 146, 092326.10.1063/1.4975321. DOI

Fung E.-D.; Gelbwaser D.; Taylor J.; Low J.; Xia J.; Davydenko I.; Campos L. M.; Marder S.; Peskin U.; Venkataraman L. Breaking Down Resonance: Nonlinear Transport and the Breakdown of Coherent Tunneling Models in Single Molecule Junctions. Nano Lett. 2019, 19, 2555–2561. 10.1021/acs.nanolett.9b00316. PubMed DOI

Amdursky N.; Ferber D.; Pecht I.; Sheves M.; Cahen D. Redox Activity Distinguishes Solid-State Electron Transport from Solution-Based Electron Transfer in a Natural and Artificial Protein: Cytochrome C and Hemin-Doped Human Serum Albumin. Phys. Chem. Chem. Phys. 2013, 15, 17142–17149. 10.1039/c3cp52885e. PubMed DOI

Fereiro J. A.; Kayser B.; Romero-Muniz C.; Vilan A.; Dolgikh D. A.; Chertkova R. V.; Cuevas J. C.; Zotti L. A.; Pecht I.; Sheves M.; et al. A Solid-State Protein Junction Serves as a Bias-Induced Current Switch. Angew. Chem., Int. Ed. 2019, 58, 11852–11859. 10.1002/anie.201906032. PubMed DOI

Fereiro J. A.; Yu X.; Pecht I.; Sheves M.; Cuevas J. C.; Cahen D. Tunneling Explains Efficient Electron Transport via Protein Junctions. Proc. Natl. Acad. Sci. U. S. A. 2018, 115, 4577–4583. 10.1073/pnas.1719867115. PubMed DOI PMC

Kayser B.; Fereiro J. A.; Guo C.; Cohen S. R.; Sheves M.; Pecht I.; Cahen D. Transistor Configuration Yields Energy Level Control in Protein-Based Junctions. Nanoscale 2018, 10, 21712–21720. 10.1039/C8NR06627B. PubMed DOI

Shallow conductance decay along the heme array of a single tetraheme protein wire

Electrochemistry in sensing of molecular interactions of proteins and their behavior in an electric field

Photoinduced hole hopping through tryptophans in proteins