Femtosecond visible transient absorption spectroscopy of chlorophyll- f -containing photosystem II

Noura Zamzam (1) , Rafal Rakowski (1) , Marius Kaucikas (1) , Gabriel Dorlhiac (1) , Sefania Viola (1) , Dennis Nürnberg (1) , Andrea Fantuzzi (1) , A. William Rutherford (1) , Jasper van Thor (1)

1 Imperial College London

Significance Far-red photosystem II (FR-PSII) contains a small number of FR-chlorophylls (- f or - d ) with the rest (∼85%) being chlorophyll- a molecules. Here ultrafast studies on FR-PSII support a model in which the primary electron donor is a FR-chlorophyll (P 720 , likely in the Chl D1 position), while the second electron donor is chlorophyll- a at the P D1 position, forming P D1 +• . Excitation energy transfer from chlorophyll- a to the FR-chlorophylls is ultrafast. The excited state of FR-chlorophyll remains highly localized, i.e., P 720 * does not share the excitation with the chlorophyll- a pigments. This is markedly different from both the conventional, chlorophyll- a PSII, and the chlorophyll- d PSII of Acaryochloris marina . The entropic and site-energy differences result in efficient but apparently slower stabilization of the charge-separated state.

Domaines: Sciences du Vivant [q-bio]

Noura Zamzam, Rafal Rakowski, Marius Kaucikas, Gabriel Dorlhiac, Sefania Viola, et al.. Femtosecond visible transient absorption spectroscopy of chlorophyll- f -containing photosystem II. Proceedings of the National Academy of Sciences of the United States of America, 2020, 117 (37), pp.23158-23164. ⟨10.1073/pnas.2006016117⟩. ⟨hal-04004130⟩