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Nat Commun. 2017 May 3;8:15274. doi: 10.1038/ncomms15274.

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

Author information

1
Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste, UMR 7141, Institut de Biologie Physico-Chimique, CNRS/Université Pierre et Marie Curie, Paris 75005, France.
2
Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, UMR 7099, Institut de Biologie Physico-Chimique, CNRS/Université Paris Diderot, Paris 7, Paris 75005, France.
3
Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités, UPMC Univ. Paris 06, CNRS UMR 8640 PASTEUR, 24, rue Lhomond, Paris 75005, France.

Abstract

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.

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