RII Track-4:NSF: Tracking assembly intermediates of the Photosystem II oxygen-evolving complex

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Plants and some microbes use photosynthesis to efficiently convert solar energy to chemical energy. However, the detailed mechanisms used in natural photosynthesis are not fully understood. By learning how biology makes fuels using cheap resources (sunlight, water, proteins, abundant metals), molecular-level blueprints can be generated for catalysis strategies with industrial and energy applications. This project aims to reveal the mechanism by which manganese and calcium ions bind to a photosynthetic protein to make an active site where molecular oxygen is released when water is oxidized. Protein samples will be prepared in the PI’s home laboratory and then studied using advanced instrumentation in the Solar Energy Conversion Group at Argonne National Laboratory (ANL). The PI and one graduate student will gain hands-on experience in spectroscopic techniques. Skills learned during this fellowship will advance the development of this type of instrumentation at the home institution to increase research capabilities and provide opportunities for future students.This project aims to reveal the chemical mechanism of the assembly of the Photosystem II oxygen-evolving complex (OEC). This metallic cluster is built in situ from free manganese ions, calcium ions, and water without the use of protein transporters or scaffolds. Advanced electron paramagnetic resonance (EPR) spectroscopy tools available at ANL will be used to characterize protein samples prepared to mimic various stages of OEC assembly. The hosts at ANL will provide facility access, training, technical expertise, and assistance with data analysis. Through this work, new insights into the mechanism of OEC assembly will be produced and a new collaboration between the PI and hosts at ANL will be established. The skills and knowledge in advanced EPR methods gained by the PI will be used to improve the research infrastructure in Louisiana.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.