Redesigning the QA binding site of Photosystem II allows reduction of exogenous quinones

Han-Yi Fu (1) , Daniel Picot (2) , Yves Choquet (1) , Guillaume Longatte (3) , Adnan Sayegh (3) , Jérôme Delacotte (3) , Manon Guille-Collignon (3) , Frédéric Lemaître (3) , Fabrice Rappaport (1) , Francis-André Wollman (1)

1 PMMC - Physiologie membranaire et moléculaire du chloroplaste
2 LBPC-PM (UMR_7099) - Laboratoire de biologie physico-chimique des protéines membranaires
3 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)

Strategies to harness photosynthesis from living organisms to generate electrical power have long been considered, yet efficiency remains low. Here, we aimed to reroute photosynthetic electron flow in photosynthetic organisms without compromising their phototrophic properties. We show that 2,6-dimethyl-p-benzoquinone (DMBQ) can be used as an electron mediator to assess the efficiency of mutations designed to engineer a novel electron donation pathway downstream of the primary electron acceptor QA of Photosystem (PS) II in the green alga Chlamydomonas reinhardtii. Through the use of structural prediction studies and a screen of site-directed PSII mutants we show that modifying the environment of the QA site increases the reduction rate of DMBQ. Truncating the C-terminus of the PsbT subunit protruding in the stroma provides evidence that shortening the distance between QA and DMBQ leads to sustained electron transfer to DMBQ, as confirmed by chronoamperometry, consistent with a bypass of the natural QA°− to QB pathway.

Domaines: Autre; Biochimie [q-bio.BM]

Han-Yi Fu, Daniel Picot, Yves Choquet, Guillaume Longatte, Adnan Sayegh, et al.. Redesigning the QA binding site of Photosystem II allows reduction of exogenous quinones. Nature Communications, 2017, 8, pp.15274. ⟨10.1038/ncomms15274⟩. ⟨hal-01526458⟩