The initial charge separation step in oxygenic photosynthesis

Yusuke Yoneda; Eric A Arsenault; Shiun-Jr Yang; Kaydren Orcutt; Masakazu Iwai; Graham R Fleming

doi:10.1038/s41467-022-29983-1

The initial charge separation step in oxygenic photosynthesis

Nat Commun. 2022 Apr 27;13(1):2275. doi: 10.1038/s41467-022-29983-1.

Authors

Yusuke Yoneda^{1

2

3}, Eric A Arsenault^{1

2

4}, Shiun-Jr Yang^{1

2}, Kaydren Orcutt^{1

2}, Masakazu Iwai^{2

5}, Graham R Fleming^{6

7

8}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, CA, 94720, United States.
² Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, United States.
³ Research Center of Integrative Molecular Systems, Institute for Molecular Science, National Institute of Natural Sciences, Okazaki, Aichi, 444-8585, Japan.
⁴ Kavli Energy Nanoscience Institute at Berkeley, Berkeley, CA, 94720, United States.
⁵ Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, United States.
⁶ Department of Chemistry, University of California, Berkeley, CA, 94720, United States. grfleming@lbl.gov.
⁷ Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, United States. grfleming@lbl.gov.
⁸ Kavli Energy Nanoscience Institute at Berkeley, Berkeley, CA, 94720, United States. grfleming@lbl.gov.

Abstract

Photosystem II is crucial for life on Earth as it provides oxygen as a result of photoinduced electron transfer and water splitting reactions. The excited state dynamics of the photosystem II-reaction center (PSII-RC) has been a matter of vivid debate because the absorption spectra of the embedded chromophores significantly overlap and hence it is extremely difficult to distinguish transients. Here, we report the two-dimensional electronic-vibrational spectroscopic study of the PSII-RC. The simultaneous resolution along both the visible excitation and infrared detection axis is crucial in allowing for the character of the excitonic states and interplay between them to be clearly distinguished. In particular, this work demonstrates that the mixed exciton-charge transfer state, previously proposed to be responsible for the far-red light operation of photosynthesis, is characterized by the Chl_D1⁺Phe radical pair and can be directly prepared upon photoexcitation. Further, we find that the initial electron acceptor in the PSII-RC is Phe, rather than P_D1, regardless of excitation wavelength.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Electron Transport
Light
Oxygen*
Photosynthesis
Photosystem II Protein Complex* / metabolism

Substances

Photosystem II Protein Complex
Oxygen