A Spotlight on the Compatibility between XFEL and Ab Initio Structures of the Oxygen Evolving Complex in Photosystem II.
The Mn4CaO5cluster of photosystem II promotes a crucial step in the oxygenic photosynthesis, namely, the water-splitting reaction. The structure of such cluster in the S1state of the Kok-Joliot's cycle has been recently resolved by femtosecond X-ray free-electron laser (XFEL) measurements. However, the XFEL results are characterized by appreciable discrepancies with previous X-ray diffraction (XRD), as well as with S1models based on ab initio calculations. We provide here a unifying picture based on a combined set of DFT-based structures and molecular dynamics simulations of the S0and S1states. Our findings indicate that the XFEL results cannot be interpreted on the grounds of a single structure. A combination of two S1stable isomers together with a minority contribution of the S0state is necessary to reproduce XFEL results within 0.16 Å.
Institute of Chemical Sciences and Engineering, École polytechnique fédérale de Lausanne, Av. F.-A. Forel 2, 1015, Lausanne, Switzerland.
Daniele
D
Narzi
<Istituto di Struttura della Materia del Consiglio Nazionale delle Ricerche, Via Salaria, Km. 29.300, 00016, Monterotondo (RM), Italy.
Giuseppe
http://orcid.org/0000-0001-6331-198X
G
Mattioli
Pangea Formazione s.r.l., via Gaspare Gozzi, 55, 00145, Rome, Italy.|Dipartimento di Scienze Fisiche e Chimiche, Università degli studi dell'Aquila, Via Vetoio (Coppito), 67100, L'Aquila, Italy.
Daniele
D
Bovi
Dipartimento di Scienze Fisiche e Chimiche, Università degli studi dell'Aquila, Via Vetoio (Coppito), 67100, L'Aquila, Italy.
Leonardo
http://orcid.org/0000-0002-2497-9482
L
Guidoni
X-ray free-electron laser; density functional calculations; molecular dynamics; photosystem II; water splitting