Collaborative Research: Unraveling the Initial Charge Separation Mechanism in Photosystem I: A Synergistic Approach

With the support of the Chemistry of Life Processes program in the Division of Chemistry, Professor Wu Xu from the University of Louisiana at Lafayette, and Professors Sergei Savikhin and Lyudmila Slipchenko from Purdue University will investigate the molecular mechanism of the initial charge transfer in photosystem I complex. Photosystem I is found in all plants, algae, and oxygenic bacteria on Earth. It is one of the major components of photosynthetic machinery that captures the energy of sunlight and powers life on the planet. The goal of the proposed research is to provide a detailed and unambiguous picture of the process that enables photosystem I to convert absorbed sunlight into motion of charges, i.e. electrical current. The work will be conducted through the unique synergistic combination of genetic engineering, ultrafast optical spectroscopy, and predictive molecular modeling. A practical value of the proposed research is in its potential impact on the advancement of natural and bio-inspired systems for energy production. This work will provide graduate and undergraduate students with truly multidisciplinary experience and reinforce the role of such collaborations in the future generation of scientists. Despite three decades of intense investigation, critical details of charge separation in photosystem I are still lacking. There is no consensus on the kinetics and molecular mechanism of the primary charge separation in the photosystem I reaction center. The proposed work will address these research questions. Genetic engineering targeting the properties of various cofactors within the photosystem I reaction center combined with ultrafast optical spectroscopy will provide a wealth of data that carries indirect information on the electron transfer in the complex. This data will be used to validate and refine first-principles modeling strategies in which the only experimental input is the structure of the photosystem I complex. The validated first-principles model will facilitate the interpretation of the experimental data and suggest new specific mutations with anticipated effects on photosystem I properties. This multifaceted, synergistic project is being conducted by a team of investigators who have extensive expertise and experience in photosynthetic research and an established track record of collaboration. 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.