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

• Published in: Nature communications Vol. 8; no. 1; p. 15274
• Main Authors: Fu, Han-Yi, Picot, Daniel, Choquet, Yves, Longatte, Guillaume, Sayegh, Adnan, Delacotte, Jérôme, Guille-Collignon, Manon, Lemaître, Frédéric, Rappaport, Fabrice, Wollman, Francis-André
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03-05-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 38/70; 38/77; 42/44; 631/449/1734; 631/57/1464; Binding sites; Biochemistry; Biochemistry, Molecular Biology; Chemical Sciences; Electrodes; Electrons; Humanities and Social Sciences; Life Sciences; multidisciplinary; Other; Peptides; Photosynthesis; Science; Science (multidisciplinary); France
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15274

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 Q
A
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 Q
A
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 Q
A
and DMBQ leads to sustained electron transfer to DMBQ, as confirmed by chronoamperometry, consistent with a bypass of the natural Q
A
°
−
to Q
B
pathway.
Devices that harness electron flow from photosynthetic organisms generally compromise host photosynthesis. Here, the authors show that, by redesigning the Q
A
site of Photosystem II, it is possible to reroute electrons to an exogenous quinone while maintaining endogenous photosynthetic electron transfer in a green alga.