Strategies to improve photosynthesis by modifying the RuBisCO system and its limitations

RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the primary enzyme responsible for carbon fixation in the Calvin-Benson-Bassham cycle, yet it remains one of the most inefficient enzymes in nature. Its slow catalytic rate, low specificity for CO₂ over O₂, and susceptibility to inhibition and heat stress limit photosynthetic efficiency and crop productivity, particularly under fluctuating environmental conditions. This review highlights current strategies to enhance RuBisCO performance. These include direct mutagenesis, ancestral protein reconstruction, and the incorporation of chimeric or heterologous RuBisCO subunits to improve kinetics and stability. Enhancing the expression of native or foreign RuBisCO subunits, as well as engineering thermostable RuBisCO activase, further supports improved photosynthetic capacity. Additionally, the integration of carbon-concentrating mechanisms such as cyanobacterial carboxysomes and algal pyrenoids offers promising avenues to increase CO₂ availability around RuBisCO. Emerging synthetic biology approaches, including artificial carbon fixation pathways, aim to bypass the limitations of natural photosynthesis altogether. We have also discussed the limitations of each method. Complementing these advances, artificial intelligence and machine learning are being increasingly used to predict beneficial mutations, model enzyme behaviour, and guide protein engineering. Together, these multidisciplinary strategies hold great potential to optimize RuBisCO, improve crop yields, and enhance resilience in a changing climate.