Engineering α-carboxysomes into plant chloroplasts to support autotrophic photosynthesis
Taiyu Chen, Marta Hojka, Philip Davey, Yaqi Sun, Gregory F. Dykes, Fei Zhou, Tracy Lawson, Peter J. Nixon, Yongjun Lin, Lu‐Ning Liu
Abstract
Abstract The growth in world population, climate change, and resource scarcity necessitate a sustainable increase in crop productivity. Photosynthesis in major crops is limited by the inefficiency of the key CO 2 -fixing enzyme Rubisco, owing to its low carboxylation rate and poor ability to discriminate between CO 2 and O 2 . In cyanobacteria and proteobacteria, carboxysomes function as the central CO 2 -fixing organelles that elevate CO 2 levels around encapsulated Rubisco to enhance carboxylation. There is growing interest in engineering carboxysomes into crop chloroplasts as a potential route for improving photosynthesis and crop yields. Here, we generate morphologically correct carboxysomes in tobacco chloroplasts by transforming nine carboxysome genetic components derived from a proteobacterium. The chloroplast-expressed carboxysomes display a structural and functional integrity comparable to native carboxysomes and support autotrophic growth and photosynthesis of the transplastomic plants at elevated CO 2 . Our study provides proof-of-concept for a route to engineering fully functional CO 2 -fixing modules and entire CO 2 -concentrating mechanisms into chloroplasts to improve crop photosynthesis and productivity.