Ribulose -1,5- Bisphosphate Carboxylase Oxygenase (Rubisco) is one of the most important enzymes on the planet. Responsible for the carbon fixation step of photosynthesis, it underpins all of life. Despite its crucial role, Rubisco is still an incredibly inefficient and poorly selective enzyme, often confusing its CO2 substrate with O2, leading to the energy-intensive and wasteful photorespiration pathway. Autotrophic organisms have developed numerous mechanisms to overcome Rubisco’s limitations including carbon-concentrating mechanisms (CCMs) such as pyrenoids and carboxysomes1. However, critical C3 plants such as rice and soybean simply over-produce Rubisco to the point that it represents up to 50% of soluble leaf protein2. This comes with a significant energy cost to the plant and results in a bottleneck in the growth of important food crops.
In this presentation, I will outline our work designing a novel synthetic carbon-fixing organelle based on encapsulin protein cages. I discuss our results packaging Rubiscos from plants and prokaryotes into the encapsulin from Q. thermotolerans3 while retaining catalytic activity. I will go on to discuss the kinetics of encapsulated Rubiscos, protection conferred from being sequestered in an encapsulin shell and outline our next steps toward engineering a complete novel CCM compatible with C3 plants.