Going around the Kok cycle of the water oxidation reaction with femtosecond X-ray crystallography. Bhowmick, A., Simon, P. S., Bogacz, I., Hussein, R., Zhang, M., Makita, H., Ibrahim, M., Chatterjee, R., Doyle, M. D., Cheah, M. H., Chernev, P., Fuller, F. D., Fransson, T., Alonso-Mori, R., Brewster, A. S., Sauter, N. K., Bergmann, U., Dobbek, H., Zouni, A., Messinger, J., Kern, J., Yachandra, V. K., & Yano, J. IUCrJ, 10(6):642–655, November, 2023. Number: 6 Publisher: International Union of Crystallography
Going around the Kok cycle of the water oxidation reaction with femtosecond X-ray crystallography [link]Paper  doi  abstract   bibtex   
The water oxidation reaction in photosystem II (PS II) produces most of the molecular oxygen in the atmosphere, which sustains life on Earth, and in this process releases four electrons and four protons that drive the downstream process of CO2 fixation in the photosynthetic apparatus. The catalytic center of PS II is an oxygen-bridged Mn4Ca complex (Mn4CaO5) which is progressively oxidized upon the absorption of light by the chloro­phyll of the PS II reaction center, and the accumulation of four oxidative equivalents in the catalytic center results in the oxidation of two waters to di­oxy­gen in the last step. The recent emergence of X-ray free-electron lasers (XFELs) with intense femtosecond X-ray pulses has opened up opportunities to visualize this reaction in PS II as it proceeds through the catalytic cycle. In this review, we summarize our recent studies of the catalytic reaction in PS II by following the structural changes along the reaction pathway via room-temperature X-ray crystallography using XFELs. The evolution of the electron density changes at the Mn complex reveals notable structural changes, including the insertion of OX from a new water molecule, which disappears on completion of the reaction, implicating it in the O—O bond formation reaction. We were also able to follow the structural dynamics of the protein coordinating with the catalytic complex and of channels within the protein that are important for substrate and product transport, revealing well orchestrated conformational changes in response to the electronic changes at the Mn4Ca cluster.
@article{bhowmick_going_2023,
	title = {Going around the {Kok} cycle of the water oxidation reaction with femtosecond {X}-ray crystallography},
	volume = {10},
	copyright = {https://creativecommons.org/licenses/by/4.0/},
	issn = {2052-2525},
	url = {https://journals.iucr.org/m/issues/2023/06/00/it5029/},
	doi = {10.1107/S2052252523008928},
	abstract = {The water oxidation reaction in photosystem II (PS II) produces most of the molecular oxygen in the atmosphere, which sustains life on Earth, and in this process releases four electrons and four protons that drive the downstream process of CO2 fixation in the photosynthetic apparatus. The catalytic center of PS II is an oxygen-bridged Mn4Ca complex (Mn4CaO5) which is progressively oxidized upon the absorption of light by the chloro­phyll of the PS II reaction center, and the accumulation of four oxidative equivalents in the catalytic center results in the oxidation of two waters to di­oxy­gen in the last step. The recent emergence of X-ray free-electron lasers (XFELs) with intense femtosecond X-ray pulses has opened up opportunities to visualize this reaction in PS II as it proceeds through the catalytic cycle. In this review, we summarize our recent studies of the catalytic reaction in PS II by following the structural changes along the reaction pathway via room-temperature X-ray crystallography using XFELs. The evolution of the electron density changes at the Mn complex reveals notable structural changes, including the insertion of OX from a new water molecule, which disappears on completion of the reaction, implicating it in the O—O bond formation reaction. We were also able to follow the structural dynamics of the protein coordinating with the catalytic complex and of channels within the protein that are important for substrate and product transport, revealing well orchestrated conformational changes in response to the electronic changes at the Mn4Ca cluster.},
	language = {en},
	number = {6},
	urldate = {2024-10-16},
	journal = {IUCrJ},
	author = {Bhowmick, A. and Simon, P. S. and Bogacz, I. and Hussein, R. and Zhang, M. and Makita, H. and Ibrahim, M. and Chatterjee, R. and Doyle, M. D. and Cheah, M. H. and Chernev, P. and Fuller, F. D. and Fransson, T. and Alonso-Mori, R. and Brewster, A. S. and Sauter, N. K. and Bergmann, U. and Dobbek, H. and Zouni, A. and Messinger, J. and Kern, J. and Yachandra, V. K. and Yano, J.},
	month = nov,
	year = {2023},
	note = {Number: 6
Publisher: International Union of Crystallography},
	pages = {642--655},
}

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