Using EPR spectroscopy to probe electron transfer in biology: from model molecular wires to complex metalloenzymes

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A fully funded PhD position is available in the Roessler research group as part of the Centre for Pulse EPR spectroscopy (PEPR). PEPR is a major new facility at Imperial College London and was recently launched at the White City Campus. The Roessler group investigates unpaired electrons in redox reactions that underpin essential chemical reactions in respiration and photosynthesis. We apply pulse EPR techniques [1] to understand the mechanisms of challenging enzymes that cannot be obtained in high concentrations and require precise electrochemical potential adjustment [2,3]. We are also developing film-electrochemical EPR spectroscopy (FE-EPR), an exciting technique for studying the evolution of radicals during a reaction [4]. FE EPR allows the accurate determination of the redox potentials of buried redox centres within enzymes and their activity during catalysis. PEPR combines pulse EPR at X- and Q-band frequencies with FE-EPR and instrument development in collaboration with University College London and the London Centre of Nanotechnology [5].In this project, you will apply the state-of-art instrumentation available at PEPR, together with the unique capabilities of FE-EPR, to build on our recent findings of electron transfer within photosynthetic complex I [2] and energy-coupling in respiratory complex [3]. You will acquire a fundamental understanding of how best to harness the recent advances in pulse EPR to investigate complex paramagnetic centres using model molecular wires. Using this foundation, we will study how complex I type enzymes use electron transfer to pump protons that are essential for ATP synthesis. The project is interdisciplinary and collaborative, and depending on your choice of focus for your project you will have the opportunity to combine physics/physical chemistry (advanced EPR, electrochemistry), material science (for the fabrication and characterisation of electrodes), biochemical methods (making and manipulating membrane proteins) and chemical synthesis (making model molecular wires). You should have a keen interest and background in physical chemistry or biochemistry. Previous exposure to EPR spectroscopy is an asset but not an essential requirement.[1] M. M. Roessler and E. Salvadori, 'Principles and Applications of EPR Spectroscopy in the chemical sciences', Chemical Society Reviews, 2018, 47 (8), 2534-2553[2] K.H. Richardson, J.J. Wright, M. Simenas, J. Thiemann, A.M. Esteves, G. McGuire, W.K. Myers, J.J.L. Morton, M. Hippler, M.M. Nowaczyk, G.T. Hanke, M.M. Roessler, 'Functional basis of electron transport within photosynthetic complex I', Nature Communications, 2021, 12, 5387, Press Release[3] N. le Breton, J. J. Wright, A.J.Y.J. Jones, E. Salvadori, H. R. Bridges, J. Hirst, M. M. Roessler, 'Using EPR Hyperfine Spectroscopy to define the Proton-Coupled Electron Transfer Reaction at Fe-S cluster N2 in Respiratory Complex I', J. Am. Chem. Soc., 2017, 139 (45), 16319-16326, Spotlight Article[4] K. Abdiaziz, E. Salvadori, K.P. Sokol, E. Reisner, M.M. Roessler, 'Protein film electrochemical EPR spectroscopy as a technique to investigate redox reactions in biomolecules', Chemical Communications, 2019, 55 (60), 8840-8843[5] M Simenas, J O'Sullivan, CW Zollitsch, O Kennedy, M Seif-Eddine, I Ritsch, M Hulsmann, M Qi, A Godt, MM Roessler, G Jeschke, JJL Morton, 'A sensitivity leap for X-band EPR using a probehead with a cryogenic preamplifier', Journal of Magnetic Resonance 2021 322, 106876