Crops & Soil - Regulation of Rubisco in a synthetic pyrenoid-like condensate expressed in rice

Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the driving force behind CO2 assimilation in plants. Despite its importance, Rubisco is a slow and error-prone enzyme, and thus a key limiting factor for growth. This limitation is particularly evident in staple C3 crops, such as rice. To compensate, some organisms have evolved CO2-concentrating mechanisms (CCMs) that increases the efficiency of Rubisco. In algae, Rubisco is condensed within a liquid-like, phase separated microcompartment called the pyrenoid, in association with a CCM that enhance photosynthetic efficiencies. Introducing an algal CCM into a C3 crop could improve the performance of Rubisco and significantly increase yields and the efficiency of food production.

Three recent developments have opened up exciting new avenues to engineer Rubisco and build an algal CCM into a crop plant: i) pyrenoid-like condensates can now be generated in plants by modification of the small subunit of Rubisco (SSU) and introduction of algal components1, ii) CRISPR/Cas approaches are able to replace the SSU family in crop plants (e.g. in rice2), iii) plant Rubiscos can be assembled in vitro (i.e. in E. coli3). This project will aim to assemble a pyrenoid in rice and characterise the performance and regulation of Rubisco within the liquid-like condensate.