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SFB Publication in Proc. Natl. Acad. Sci. USA

SFB 1078 Project A5 PIs Athina Zouni and Holger Dobbek and coworkers together with an international consortium of scientists published their results of time-resolved XFEL experiments on electronic transitions in photosystem II in the journal PNAS. Their study reveals a key step of photosynthetic water splitting in PS II, which could be a pillar for next generation artificial photosynthetic systems for clean-energy production.

News from Jul 16, 2020

Untangling the sequence of events during the S2 → S3 transition in photosystem II and implications for the water oxidation mechanism:

A new bridging oxygen ligand is incorporated between one ofthe Mn atoms and Ca in the Mn4Ca cluster during the transitionfrom the one-photon induced S2 intermediate state to the two-photon induced S3 state in the catalytic water oxidation re-action in photosystem II. However, the sequence of events leadingto this change is not known. In this paper, the authors report an X-ray crystallog-raphy and spectroscopy study at room temperature using an X-ray free electron laser to collect a "molecular movie" of the structuraland oxidation state change steps leading to the insertion of thisnew oxygen bridge, in the 50 μs to 200 ms time scales afterphoton absorption, which triggers the S2 → S3 state transition.

Ibrahim, M., Fransson, T., Chatterjee, R., Cheah, M. H., Hussein, R., Lassalle, L., Sutherlin, K. D., Young, I. D., Fuller, F. D., Gul, S., Kim, I.-S., Simon, P. S., de Lichtenberg, C., Chernev, P., Bogacz, I., Pham, C. C., Orville, A. M., Saichek, N., Northen, T., Batyuk, A., Carbajo, S., Alonso-Mori, R., Tono, K., Owada, S., Bhowmick, A., Bolotovsky, R., Mendez, D., Moriarty, N. W., Holton, J. M., Dobbek, H., Brewster, A. S., Adams, P. D., Sauter, N. K., Bergmann, U., Zouni, A., Messinger, J., Kern, J., Yachandra, V. K., and Yano, J. (2020).
PNAS 117, 12624-12635. doi: 10.1073/pnas.2000529117

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