Remodeling of the Photosynthetic Chain Promotes Direct CO2 Conversion into Valuable Aromatic Compounds.

Directing CO2 conversion using photosynthetic microorganisms offers a promising route to couple CO2 sequestration with petrochemical replacement. However, the low-flux shikimate pathway remains largely unexploited for the synthesis of valuable aromatics. In addition, it is unclear how an enhanced low-flux pathway would influence the photosynthetic chain. We created a powerful metabolic sink by introducing the 2-phenylethanol pathway and an artificial feedback-inhibition-resistant cassette to Synechococcus elongatus. More than 30 % of the fixed carbon was redirected to the shikimate pathway for aromatic synthesis, and carbon fixation and O2 evolution increased significantly. A "self-remodeling" mechanism of the photosynthetic chain was discovered, which accelerates electron transport and reduces energy waste. This study represents a significant step toward the industrial viability of CO2 conversion into aromatic compounds and provides design guidance for improving photosynthetic efficiency.