Biochemical characterization of Bnd4, structural elucidation of 2, and biosynthesis of 1. (A) Bnd4 and TSAa catalyze the cyclization of GGPP into 2. Enzyme reactions, including a no enzyme control (GGPP), were analyzed by HPLC by monitoring at 210 nm. (B) GCMS spectrum of pure 2. (C) Structure of 2 and key 2D NMR correlations supporting its structural assignment. (D) Biosynthetic gene cluster (bnd) and proposed biosynthetic pathway for 2. The formation of 2, a novel 6,10-bicyclic scaffold, by a unique TS, precedes oxidative tailoring affording 1.