Fig. 1.

Overview of formolase pathway reactions. (A) Benzaldehyde lyase couples two benzaldehydes into benzoin through an acyloin addition reaction. (B) Acetyl-CoA synthase (ACS) catalyzes the ATP-dependent conversion of acetate into acyl-CoA. (C) Acetaldehyde dehydrogenase (ACDH) catalyzes the NADH-dependent reduction of acetyl-CoA to acetaldehyde. (D) Conversion of formate to dihydroxyacetone phosphate (DHAP) by the formolase pathway. To generate reducing equivalents in the cell, formate is oxidized by formate dehydrogenase (FDH) to produce CO₂ and NADH (stage 1). To use formate as a carbon source, activation (stage 2) and carbon-carbon coupling (stage 3) to form dihydroxyacetone (DHA) are carried out by the enzymes ACS, ACDH, and formolase (FLS). DHA is phosphorylated to DHAP, a glycotic intermediate by a dihydroxyacetone kinase (DHAK) (stage 4). The novel enzyme functions identified here are underlined.