Faculty of Science
Faculty of Science
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Structural Biology and Biophysics (Engel)

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Cryo-Electron Tomography for the Ocean (cryOcean): Molecular Architecture and Photosynthetic Adaptation of Marine Algae

Research Project  | 1 Project Members

Chloroplasts in marine algae perform 25% of the Earth's photosynthesis, sustaining vast food webs and powering the global carbon cycle. However, the molecular organization of these vital photosynthetic organelles remains uncharted. Moreover, marine algae have diverse evolutionary lineages, so the mechanisms that regulate light harvesting and carbon fixation cannot be generalized from model land plants and freshwater algae. As climate change dramatically reshapes our world, it is of timely importance to understand how chloroplast architecture in marine algae responds to the ocean's rapidly fluctuating environmental conditions. To define conserved and divergent strategies of photosynthesis, we will chart the molecular architecture of chloroplasts in diverse and globally important marine algae by combining genetic manipulation and environmental conditioning with our pioneering cryo-electron tomography approach, which resolves the structures and organization of molecular complexes within the native chloroplast. We will reveal the light-harvesting thylakoid membranes and carbon-fixing pyrenoids with molecular detail, dissecting the events of organelle biogenesis, environmental remodeling, and repair from stress-induced damage. We will begin with mechanistic in vivo and in vitro studies of diatoms, the most globally productive marine algae. Then, we will make evolution-spanning comparisons to coccolithophores, which sequester gigatons of CO 2 each year, and Symbiodinium , which bring life to coral reefs. Finally, we will explore the ecological relevance of this chloroplast architecture by comparing to diverse algae sampled directly from the ocean. The cryOcean project will yield fundamental insights into how chloroplast architecture directs light harvesting and carbon fixation in marine algae, and will reveal how this architecture adapts to environmental stress. These discoveries will expand the molecular toolbox for engineering photosynthesis to resist climate change.