Supercharging Sustainability: Harnessing Hyperactive Carbon-Fixing Enzymes for Food Security and Green Industry

We have developed a hyperactive carbon-fixing enzyme to tackle the dual challenges of food security and sustainable industry. We will produce new fast-growing plants and photosynthetic bacteria for a step change in sustainability research. In the face of a changing climate, the world faces a growing sustainability crisis and an urgent need to adapt industry to reduce greenhouse emissions and environmental impact. A growing population, climate change, and soil desertification mean many people are already food insecure, and millions face the same prospect in coming decades. Food security is underpinned directly or indirectly via plant-based agriculture for food and feed. A significant change is also needed in how chemicals are made to reduce fossil fuel requirements and thus make their production more sustainable. Photosynthetic carbon fixation underpins all life on Earth. The enzyme Rubisco is central to carbon fixation by photosynthesis. It is the gatekeeper of carbon entry into the biosphere, the most abundant protein on the planet, and an essential yet imperfect catalyst. Rubisco often limits photosynthetic carbon assimilation and growth. Therefore, improving Rubisco catalytic efficiency is an economically high-value strategic research goal to increase yields in agriculture and the sustainability benefits and efficiency gains through green biotechnology using photosynthetic prokaryotes. A poorly understood aspect of Rubisco biochemistry is the role of post-translational modifications (PTMs) to the primary structure that could regulate its activity in vivo. We have identified a previously unknown carbon dioxide binding site on Rubisco. We have demonstrated that ablating this binding site gives a remarkable increase in Rubisco’s carbon-fixing activity. Further, we have shown that eliminating this binding site from the chromosome of a photosynthetic prokaryote gives a new, fast-growing strain. Therefore, we have an exciting and exploitable tool for tackling sustainability challenges, and contributing toward priority efforts to use biosciences research to advance sustainable agriculture, and produce renewable resources to power clean growth. The proposal builds on these findings through three experimental streams. We will fully characterise the impact of this PTM on the biochemistry of both plant cyanobacterial Rubiscos. This will be important to understand the mechanistic basis behind changes in catalysis, and how broadly transferable this discovery will be. We will exploit our fast-growing strain as a green bio-factory for industrial biotechnology by examining the impact on the yield of high-value bio-alcohols. This objective will have a near-term impact on research in pursuit of alternative chemical synthesis routes that reduce global reliance on fossil fuels. We will generate tobacco plants with mutated Rubisco large subunits to characterise the effect of this PTM on plant-level photosynthesis and growth. This objective will establish the physiological impacts of this mutation in tobacco as a proof-of-concept for future larger scale trials and engineering of improved crop plants. Together, the objectives will develop our preliminary findings to a technology readiness level for future exploitation with industry.