Towards pairing solar chemical production with central metabolism of S. oneidensis MR-1 Alexander L. Sutton-Cook 1 , Jessica H. van Wonderen 1 , Giovanni Bressan 1 , Igor Sazanovich 2 , Greg Greetham 2 , Julea N. Butt 1 1 University of East Anglia, Norwich, Norfolk, NR4 7TJ, United Kingdom, 2 Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, OX11 0QX, United Kingdom Shewanella oneidensis MR-1 is capable of extracellular electron transfer (EET) as an alternative method of enabling continued central metabolic function in the absence of oxygen. A key component of this EET mechanism is the extracellular decahaem protein MtrC, bound to the outer membrane by a lipid anchor. MtrC receives electrons from intracellular central metabolism via a redox active outer membrane spanning protein and channels those electrons through His/His ligated haems to metal oxides in the surrounding soil. 1 Functionalization of the MtrC cytochrome wire with a blue-light sensitive ruthenium dye could enable the released electrons to be energised to power valorising reductive chemistry, for example proton or CO2 reduction. 2 Site-directed mutagenesis of MtrC enables cysteine introduction for subsequent covalent bonding to Ru(4-bromomethyl-4’- methylbipyridine)(2,2’-bipyridine) 2 (RuMeBr). 3 Two sites on the surface of MtrC (S634 and Y657) have been chosen for replacement by Cys for minimal disruption of MtrC structure and a short distance (<10 Å) between the subsequently bound Ru-dye and outermost haem (haem 10) of the molecular wire. The S634C and Y657C MtrC proteins have been purified and photosensitised by reaction with RuMeBr. With the aim of extending the lifetime of the charge separated state, lowering or increasing the redox potential of the haems has also been investigated by replacing the natural His/His ligation with His/Cys (H561C) or His/Met (H561M, H230M) respectively. Rates of charge separation, haem-haem charge transfer and charge recombination between the Ru-dye and MtrC haem wire have been determined in the ps - µs time range using Time-Resolved Photoluminescence (TRPL) and Transient Absorbance Spectroscopy (TAS). This work acts as a steppingstone towards pairing advantageous photochemistry to bacterial internal metabolism. References 1. Beblawy, S.; Bursac, T.; Paquete, C.; Louro, R.; Clarke, T. A.; Gescher, J. Extracellular reduction of solid electron acceptors by Shewanella oneidensis. Molecular Microbiology 2018, 109 (5), 571-583. DOI: https://doi.org/10.1111/mmi.14067. 2. Piper, S. E. H.; Edwards, M. J.; van Wonderen, J. H.; Casadevall, C.; Martel, A.; Jeuken, L. J. C.; Reisner, E.; Clarke, T. A.; Butt, J. N. Bespoke Biomolecular Wires for Transmembrane Electron Transfer: Spontaneous Assembly of a Functionalized Multiheme Electron Conduit. Frontiers in Microbiology 2021, 12, Original Research. DOI: 10.3389/fmicb.2021.714508. 3. van Wonderen, J. H.; Adamczyk, K.; Wu, X.; Jiang, X.; Piper, S. E. H.; Hall, C. R.; Edwards, M. J.; Clarke, T. A.; Zhang, H.; Jeuken, L. J. C.; et al. Nanosecond heme-to-heme electron transfer rates in a multiheme cytochrome nanowire reported by a spectrally unique His/Met-ligated heme. Proceedings of the National Academy of Sciences 2021, 118 (39), e2107939118. DOI: 10.1073/pnas.2107939118.
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