Towards Engineering a Carboxysome Based CCM into C3 Crops

Improving the efficiency of photosynthesis is widely recognized as a promising strategy for increasing the yield of biomass and food crops. Most of the research aimed at improving photosynthesis is focused on overcoming the limitations of the primary CO2 fixing enzyme Rubisco. In cyanobacteria, bacterial microcompartments, called carboxysomes, improve the efficiency of photosynthesis by acting as a carbon concentrating mechanism (CCM) to concentrate CO2 near Rubisco. Cyanobacteria also make use of Rubiscos that are faster than those of crop plants, although they have lower specificity toward CO2 than the land plant enzyme, which increases resource use efficiency. Replacement of land plant Rubisco by faster bacterial variants with lower CO2 specificity will improve photosynthesis and resource use efficiency if installed in a microcompartment capable of concentrating CO2. Here we will report our recent progress on introducing components of the cyanobacterial CCM into plants.