Study of photosynthetic and stress-related enzymes: from functional characterization to physiological roles

As we all know, climate change poses new challenges, particularly concerning our ability to cultivate plants for food, feed, and energy in adverse environmental circumstances. In this context, a major issue regards the productivity of agricultural crops. On the one hand, plant productivity depends on plant capacity to accumulate biomass, and on the other hand, it relies on their ability to cope with both biotic and abiotic stress conditions. The thorough understanding of the molecular mechanisms underlying plant physiology is a key step in laying the foundation for future improvement. This thesis work focuses on the study of five enzymes involved in carbon metabolism. Three of them, namely glyceraldehyde 3-phosphate dehydrogenase (GAPDH), ribulose-5-phosphate-3-epimerase (RPE) and phosphoribulokinase (PRK) participate in the Calvin-Benson-Bassham cycle, the metabolic pathway ensuring the major input of carbon into the organic world and closely influencing the planet's primary productivity. The other two enzymes, namely alcohol dehydrogenase (ADH) and nitrosoglutathione reductase (GSNOR) are involved in plant adaptation to stress conditions. Specifically, ADH is directly implicated in acclimation to oxygen deficiency, while GSNOR serves as a key regulator of intracellular levels of nitrosoglutathione, a critical signalling molecule involved in stress response. The approach here employed integrates multidisciplinary analyses focused on the structural and biochemical characterization of recombinant enzymes, with a special emphasis on the investigation of potential cysteine-based regulatory mechanisms. Alongside, in vivo and ex vivo analyses have offered insights into the elucidation of the role of these enzymes in their physiological context.