Rubisco proton production can drive the elevation of CO <sub>2</sub> within condensates and carboxysomes
Benedict M. Long, Britta Förster, Sacha B. Pulsford, G. Dean Price, Murray R. Badger
Abstract
Significance Rubisco is arguably the most abundant protein on Earth, and its catalytic action is responsible for the bulk of organic carbon in the biosphere. Its function has been the focus of study for many decades, but recent discoveries highlight that in a broad array of organisms, it undergoes liquid–liquid phase separation to form membraneless organelles, known as pyrenoids and carboxysomes, that enhance CO 2 acquisition. We assess the benefit of these condensate compartments to Rubisco function using a mathematical model. Our model shows that proton production via Rubisco reactions, and those carried by protonated reaction species, can enable the elevation of condensate CO 2 to enhance carboxylation. Application of this theory provides insights into pyrenoid and carboxysome evolution.