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…

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.

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…

Synthetic biology is the forward engineering of biological systems using an ever-expanding list of biological functional modules. It aims at understanding by building biological systems through rational design. We use its concepts and tools to study photosynthesis in the model green alga Chlamydomonas reinhardtii to better understand the regulation and limitations of photosynthetic carbon fixation. Our first approach is the redesign of pathways to control in vivo the amount of each enzyme. The second project (paleo-biochemistry) aims at using Evolution as a resource (ancestral sequences inference and resurrection, directed evolution) to explore novel evolutionary paths of carbon fixation. We also aim at implementing in vivo new metabolic pathways (de novo design) to expand photosynthetic capacities. Finally, we develop the standardized tools (MoClo, logic gates) necessary to build these designs.

The storage of digital data is a major challenge in our modern societies. Current digital media stored in data centers are fragile, bulky and energy-intensive. The ongoing digital transformation of our societies requires a major disruption of our digital storage technologies. DNA data storage is an emerging technology that has the advantage of being stable for thousands of years, extremely compact and energy-efficient. Our team is developing innovative concepts of DNA data storage based on domestication of biological systems