Towards an enzyme cascade synthesis of the bulk chemical acrylic acid

Acrylic acid is a bulk chemical predominantly produced via fossil-based processes. Here, we repurpose and engineer a thiamine diphosphate (ThDP)-dependent enzyme to catalyze direct H₂PO₄⁻ elimination from dihydroxyacetone phosphate (DHAP) for acrylic acid synthesis. Quantum chemical calculations reveal the catalytic mechanism involving isomerization, enol-ThDP intermediate formation, H₂PO₄⁻ elimination, and hydrolysis. Using an automated high-throughput screening platform, we perform directed evolution and obtain a 13.6-fold improved variant, designated acrylic acid synthase (AAS). We establish an enzymatic methanol-to-acrylic acid (MAAP) pathway, achieving a titer of 4.3 g L−1, a productivity of 268.9 mg L−1 h−1, and 99.5% conversion. This work establishes a high-efficiency biomanufacturing paradigm for bulk acrylic acid, and expands the catalytic repertoire of ThDP-dependent enzymes for sustainable one-carbon conversion. Acrylic acid is a bulk chemical produced via fossil-based processes. Here the authors repurpose a thiamine diphosphate (ThDP)-dependent enzyme to catalyze H₂PO₄⁻ elimination from dihydroxyacetone phosphate for acrylic acid synthesis and establish a methanol-to-acrylic acid pathway.