Light-Driven Carbon Fixation Using Photosynthetic Organelles in Artificial Photosynthetic Cells

Building an artificial photosynthetic cell from scratch helps to understand the working mechanisms of chloroplasts. It is a challenge to achieve carbon fixation triggered by photosynthetic organelles in an artificial cell. ATP synthase and photosystem II (PSII) are purified and reconstituted onto the phospholipid membrane to fabricate photosynthetic organelles. With the integration of phycocyanin, the ATP production yield increases by 2.51-fold due to the enhanced light harvesting capability. The carbon fixation pathway is established by converting α-oxoglutarate to acetyl-CoA and oxaloacetate with cascade enzyme reactions including the isocitrate dehydrogenase (IDH), aconitase (ACO), and ATP citrate lyase (ACL). The photosynthetic organelles, phycocyanin, and carbon fixation pathway are encapsulated into giant unilamellar vesicles to obtain artificial photosynthetic cells, which convert α-oxoglutarate to acetyl-CoA and oxaloacetate inside artificial cells upon light irradiation. The acetyl-CoA is the most important intermediate product in the cellular metabolic networks for the synthesis of cholesterol and fatty acids. Our results provide a way for efficient light energy conversion to produce ATP and fix CO₂, and pave the path to build autonomous artificial cells with more complicated metabolic networks.