Fig. 2.

OA formation requires the presence of the DABB protein, olivetolic acid cyclase (OAC). (A) TKS produces the by-products PDAL, HTAL, and olivetol, but crude protein from hemp trichomes catalyzes OA formation. Assays of TKS together with polyketide cyclase candidate proteins shows OA is produced by the DABB protein OAC but not by Betv1-like and CHI-like proteins. (B) Comparison of polyketide product profiles in TKS assays performed with and without OAC (mean ± SD, n = 3). Reaction products in polyketide synthesis assays were analyzed by HPLC and identified by comparison with authentic standards (Fig. S6).