Petroutsos lab

We are investigating how CO2 acts as substrate for photosynthesis and as signaling molecule in conjunction with light to control cellular homeostasis in microalgae. We are combining genetic, molecular, biochemical, physiological and mathematical modelling approaches to identify factors regulating CO2 capture and partitioning.

Our vision

Carbon is the backbone of Life on Earth, due to its ability to form complex molecules such as DNA or proteins. Most of Earth’s carbon is stored in rocks and sediments, the rest is in the ocean, atmosphere, and in living organisms, constantly being cycled between each reservoir via the biogeochemical process called carbon cycle. The unprecedented levels of energy consumption, mainly via fossil fuel combustion, are disrupting the carbon cycle and are leading to accumulation of CO2 in the atmosphere. This poses a severe threat to our planet, destabilizing climate.


Photosynthetic microalgae are crucial to the carbon cycle by fixing CO2 into organic carbon and this is why they are key players of the planetary metabolism drawing down carbon. Our vision is that by mastering the regulatory mechanisms controlling photosynthetic CO2 metabolism we can empower the biosphere to respond more effectively to regulate atmospheric CO2 concentration and we advance towards a sustainable low carbon economy. For this we are investigating how CO2 acts as substrate for photosynthesis and as signalling molecule in conjunction with light to control cellular homeostasis in microalgae.

Highlights from our research activities

The blue light photoreceptor PHOTOTROPIN transcriptionally controls photoprotection

The view in the field has long been that induction of photoprotection in high light is a response regulated by stress perception in the chloroplast. This work challenges this view and show that the plasma membrane associated blue light photoreceptor phototropin controls photoprotection by regulating nuclear gene expression the photoprotective gene LHCSR3.

Link to article

Light-independent regulation of algal photoprotection by CO2 availability

This work represents a very new perspective on the regulation of genes involved in photoprotection, i.e. conferring protection against photooxidative stress under excess light. We demonstrate here that changes in CO2 availability regulate photoprotection, and this regulation can happen even in the complete absence of light, which was so far believed to be indispensable for the activation of this process.

Link to article

Systems biology approach unveils novel shared regulators of photoprotection and of CO2 concentration mechanism

We reconstructed a genome-scale gene regulatory network and used it to identify novel components of the transcriptional regulation of photoprotection and of the CO2-concentration mechanism. Along with demonstrating the existence of regulatory hubs that channel light- and CO2-mediated signals into a common response, this work provides a unique resource to dissect gene expression regulation in Chlamydomonas.

Link to article

Blue light perception via PHOTOTROPIN controls photosynthetic carbon partitioning

We describe the molecular mechanism by which blue light, via the photoreceptor phototropin and a newly discovered downstream protein kinase, inhibits starch accumulation in the model green microalga Chlamydomonas reinhardtii. As a result, we resolved a decades-old question as to why light quality impacts starch accumulation in green algae.

Link to abstract

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