Projects


PanArctica

Project Leader: Richard Dorrell

Work in the HEAL group is supported by an ANR JCJC, “PanArctica” (Projet-ANR-21-CE02-0014), awarded 2021-2025.The Arctic Ocean is set apart from all other oceans due to being encircled by land, its extreme environment, and its distinct ecosystem, characterised by strong seasonal succession. Anthropogenic climate change is rapidly changing the Arctic Ocean into a warmer, fresher habitat, and understanding the biological communities that support the Arctic is urgent for projecting its future robustness.The data obtained from this project will provide in-depth insights into the functional biology of an important and rapidly changing oceanic habitat. In the long term, these may allow more refined understanding of which species will proliferate in the future Arctic Ocean. In addition, proteins identified that confer temperature, salinity and photo-tolerance in Arctic native species may be explored as candidates for improving the productivity and robustness of biofuels and other cultivable crop species. 

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Project Leader: Richard Dorrell

The Haptophyte Pan-Genome

Project Leader: Richard Dorrell

Work in the HEAL Group is supported by a JGI Community Sequencing Programme grant, "the Haptophyte Pan-Genome", awarded 2022."The Haptophyte Genome Project" aims to expand the phylogenetic breadth of sequenced Haptophyte genomes, particularly freshwater samples. The Haptophytes are an ancient and complex lineage of eukaryotic algae of immense ecological importance, forming the second most significant contribution to planetary eukaryotic photosynthesis after diatoms [1, 2]. Sequencing genomes and transcriptomes of phylogenetically diverse haptophytes and relevant outgroups will address long-standing questions pertaining to: 1) the phylogenetic framework and genomic diversity of species selected from freshwater, salty continental and marine environments, 2) the transition of haptophytes between marine and freshwater systems, 3) the phylogenetic composition of the haptophyte genome with particular regard to its chloroplast, 4) key components involved in biomineralization, alkenone biosynthesis, and toxin production, 5) cellular machinery associated with mixotrophy, and 6) prevalence of pan-genomes, relevant to a heating ocean. 

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Project Leader: Richard Dorrell

ChloroMosaic

Project Leader: Richard Dorrell

Work in the HEAL Group is supported by an ERC Starting Grant, “ChloroMosaic” (grant number 101039760: https://cordis.europa.eu/project/id/101039760/fr), awarded 2023-2028.Ocean photosynthesis is performed by cyanobacteria and eukaryotic algae. These eukaryotic algae originate via the endosymbiotic acquisition of chloroplasts, and many of the most prominent marine algal groups possess chloroplasts derived from the secondary or higher endosymbiotic uptake of eukaryotic red algae. The EU-funded ChloroMosaic programme aims to understand the fundamentals of the evolution and future ecology of the planet, explaining the success of the secondary red chloroplasts in the modern ocean. The secondary red chloroplasts are evolutionary mosaics and supported by nucleus-encoded proteins of the symbiont. ChloroMosaic will perform proteomic analysis of the dinoflagellate chloroplasts to identify proteins, enabling the dominant contribution of secondary red chloroplasts to marine production and defining potential biomarkers of the resilience of algal communities to anthropogenic climate change 

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Project Leader: Richard Dorrell

Environmental Stress Responses

Project Leader: Antoine Danon

We use Chlamydomonas to try to understand how a unicellular organism adapts to survive in a hostile environment. If it has already been shown that in the face of a strong stress Chlamydomonas can trigger programmed cell death (PCD), we have discovered in our team that in response to more moderate stresses, cells aggregate forming impressive multicellular structures in which algae can be protected from the toxic environment. We are trying to uncover the mechanisms that control both PCD and aggregation in Chlamydomonas.Chlamydomonas reinhardtii is the most prominent model organism in the green algae lineage for both basic research and biotechnological applications. We use Chlamydomonas to try to understand how a unicellular organism adapts to survive in a hostile environment. Although some experiments indicate the existence of programmed cell death (PCD) in response to severe stresses in Chlamydomonas, the mechanisms controlling this process and the signaling pathways involved, have yet to be…

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Redox Signaling Network

Project Leader: Christophe Marchand

Responses to fluctuating environmental conditions are based on sophisticated signaling and metabolic regulation networks where reactive oxygen, nitrogen and sulfur species play a key role. They act mainly on specific protein cysteines by a set of redox post-translational modifications (disulfide bridges, nitrosylation, glutathionylation, persulfidation...). These modifications are controlled by the small oxidoreductases thioredoxins and glutaredoxins. We are developing, mainly in Chlamydomonas reinhardtii, innovative approaches combining chemobiology, synthetic biology and systems biology to 1/ understand the dynamics and plasticity of these redox modification networks and 2/ understand at the molecular level how reactive species, redox modifications and redox proteins act together to rapidly modulate cellular processes and metabolic pathways in order to allow adaptation and survival.

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Structure and Interactions of Calvin-Benson Enzymes

Project Leader: Julien Henri

The experimental determination of the structure of the twelve proteins of the Calvin-Benson pathway of photosynthetic carbon fixation revealed the biochemical mechanisms by which enzymes catalyze these essential reactions for the biosphere. We more specifically study how post-translational modifications (oxido-reductions and phosphorylations) modulate enzyme activities, and to which extent protein-protein interactions connect enzymes together or with their thioredoxin regulators. The full description of allosteric mechanisms and channeling shortcuts of the Calvin-Benson system is further explored by the design-building-testing of artificial multiprotein complexes. Photosynthesis is the main energy and carbon source for the biosphere. The Calvin-Benson cycle fixes atmospheric CO2 into organic trioses in the stroma of chloroplasts. While the 11 enzymes individually catalyzing the chemical steps of the cycle are known, little has been reported about their supra-molecular organization. Hence, the CALVINTERACT project ambitions to redefine the molecular basis for Calvin-Benson photosynthetic carbon fixation, in the light of the regulatory interactions that…

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