INSPirAUTOR · Understanding how Inositol Polyphosphates regulate autophagy and lipid body formation in photosynthetic organisms: crosstalk with TOR signaling.

Understanding how Inositol Polyphosphates regulate autophagy and lipid body formation in photosynthetic organisms: crosstalk with TOR signaling.

Increasing concentrations of CO2 are accumulating in the atmosphere in the latest century causing the global warming effect in the planet. Mitigation of CO2 is one of the most important problems that governments are facing in the last decade. In fact, European Union is proposing a 40% reduction of emissions by the end of 2030 in the latest Climate and Energy framework (https://ec.europa.eu/clima/policies/strategies). In this sense, biological CO2 capturing, photosynthesis and its molecular regulation is an ancient process that needs to be revisited in order to help in the reduction of this greenhouse gas. In this sense, microalgae are considered the most efficient organisms to perform this process due to their high growth rate, robust photosynthetic activity and carbon storage capacity. In green algae, fixed CO2 is normally redirected to two different fates, cell growth (proteins) and carbon storage, mainly lipids and carbohydrates in the form of starch. In this sense, the use of these microorganisms for the production of biofuels is a good alternative to land crops because it lacks the main ethical implications on food or feed market and land use. Thus, the understanding of the intracellular regulation of CO2 capturing and partitioning in green cells is fundamental in order to optimize them. In this sense, we have previously found an intersection between two signaling pathways that govern these aspects in these microorganisms. The well-conserved Target of Rapamycin (TOR) and the signaling molecules Inositol polyphosphates (InsPs) coordinate to integrate external signals within photosynthetic cells and target carbon metabolism and storage. However the molecular mechanisms that they use to communicate with each other and their common targets are still unclear. During this action, we used the unicellular green alga Chlamydomonas reinhardtii to elucidate the molecular interaction between these two pathways. First, we evaluated InsPs fluctuations after TOR inhibition and the impact of autophagy activation and lipid body formation. Second, we identified novel targets of this interaction by using proteomics approaches. Finally, we monitored InsPs levels and TOR activity under different nutrient stress conditions. Overall, our data add a new level of complexity in the understanding of carbon assimilation in green organisms that goes beyond PTMs and most likely includes protein-molecule interactions that has not been reported so far.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз