Harnessing the Sun: Structural elucidation of the photoprotective Photosystem II interactome

Splitting of water molecules by Photosystem II (PSII) in oxygenic photosynthetic organisms sustains oxygen evolution on Earth, making this complex central for life on this planet.

Sunlight is arguably the most variable source of energy in natural environments, with variations in quantity and quality occurring in the range of seconds to hours, and photosynthetic organisms evolved an ensemble of photosynthetic mechanisms to thrive in every ecosystem.

Consequently, the ecological success of photosynthesis relies on the interaction of a conserved PSII catalytic core with a plethora of interacting proteins - its interactome - to optimize light harvesting and drive the disassemble/repair cycle of excess light-damaged PSII.

The structural association of PSII with its interactome is inevitably transient and therefore recalcitrant to classic approaches for structural determination.

PHOTO-LINK will employ a novel multidisciplinary approach that combines structural proteomics, spectroscopy and cryo-electron microscopy (EM) to provide a complete picture of how photosynthetic organisms adapt their PSII interactome to ever-changing environmental conditions.

The methodological approach will be developed initially using two ecologically divergent model organisms, the vascular plant Arabidopsis thaliana (At) and marine phytoplanktonic diatom Phaeodactylum tricornutum (Pt).

The subsequent structural elucidation of the photoprotective mechanisms in the organism of choice will provide cutting-edge scientific knowledge, along with valuable directions for biotechnological improvement of light-use-efficiency in globally relevant crops to increase their productivity (thanks to data acquired in At) and/or to optimise CO2 sequestration and transformation in marine phytoplankton (thanks to data acquired in Pt).