Light-driven oxidation of water to molecular oxygen is catalyzed by the oxygen-evolving complex (OEC) in Photosystem II (PS II). This multi-electron, multi-proton catalysis requires the transport of two water molecules to and four protons from the OEC. A high-resolution 1.89 Å structure obtained by averaging all the S states and refining the data of various time points during the S 2 to S 3 transition has provided better visualization of the potential pathways for substrate water insertion and proton release. Our results indicate that the O1 channel is the likely water intake pathway, and the Cl1 channel is the likely proton release pathway based on the structural rearrangements of water molecules and amino acid side chains along these channels. In particular in the Cl1 channel, we suggest that residue D1-E65 serves as a gate for proton transport by minimizing the back reaction. The results show that the water oxidation reaction at the OEC is well coordinated with the amino acid side chains and the H-bonding network over the entire length of the channels, which is essential in shuttling substrate waters and protons.
Hussein, Rana, et al. "Structural dynamics in the water and proton channels of photosystem II during the S2 to S3 transition." Nature Communications, vol. 12, no. 1, Nov. 2021. https://doi.org/10.1038/s41467-021-26781-z
Hussein, Rana, Ibrahim, Mohamed, Bhowmick, Asmit, Simon, Philipp S., Chatterjee, Ruchira, Lassalle, Louise, Doyle, Margaret, Bogacz, Isabel, Kim, In-Sik, Cheah, Mun Hon, Gul, Sheraz, de Lichtenberg, Casper, Chernev, Petko, Pham, Cindy C., Young, Iris D., Carbajo, Sergio, Fuller, Franklin D., Alonso-Mori, Roberto, ... Yano, Junko (2021). Structural dynamics in the water and proton channels of photosystem II during the S2 to S3 transition. Nature Communications, 12(1). https://doi.org/10.1038/s41467-021-26781-z
Hussein, Rana, Ibrahim, Mohamed, Bhowmick, Asmit, et al., "Structural dynamics in the water and proton channels of photosystem II during the S2 to S3 transition," Nature Communications 12, no. 1 (2021), https://doi.org/10.1038/s41467-021-26781-z
@article{osti_1829937,
author = {Hussein, Rana and Ibrahim, Mohamed and Bhowmick, Asmit and Simon, Philipp S. and Chatterjee, Ruchira and Lassalle, Louise and Doyle, Margaret and Bogacz, Isabel and Kim, In-Sik and Cheah, Mun Hon and others},
title = {Structural dynamics in the water and proton channels of photosystem II during the S2 to S3 transition},
annote = {Abstract Light-driven oxidation of water to molecular oxygen is catalyzed by the oxygen-evolving complex (OEC) in Photosystem II (PS II). This multi-electron, multi-proton catalysis requires the transport of two water molecules to and four protons from the OEC. A high-resolution 1.89 Å structure obtained by averaging all the S states and refining the data of various time points during the S 2 to S 3 transition has provided better visualization of the potential pathways for substrate water insertion and proton release. Our results indicate that the O1 channel is the likely water intake pathway, and the Cl1 channel is the likely proton release pathway based on the structural rearrangements of water molecules and amino acid side chains along these channels. In particular in the Cl1 channel, we suggest that residue D1-E65 serves as a gate for proton transport by minimizing the back reaction. The results show that the water oxidation reaction at the OEC is well coordinated with the amino acid side chains and the H-bonding network over the entire length of the channels, which is essential in shuttling substrate waters and protons. },
doi = {10.1038/s41467-021-26781-z},
url = {https://www.osti.gov/biblio/1829937},
journal = {Nature Communications},
issn = {ISSN 2041-1723},
number = {1},
volume = {12},
place = {United Kingdom},
publisher = {Nature Publishing Group},
year = {2021},
month = {11}}
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
Caroline von Humboldt Stipendium; Exascale Computing Project; German Research Foundation (DFG); National Institutes of Health (NIH); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division