    4.2.3.17 | X-ray crystal structure of a truncation variant lacking the transit sequence and an additional 27 residues at the N-terminus, complexed with 13-aza-13,14-dihydrocopalyl diphosphate, at 1.82 A resolution, and 2-fluorogeranylgeranyl diphosphate, at 2.25 A resolution. The structure reveals a modular assembly of three alpha-helical domains. The C-terminal catalytic domain is a class I terpenoid cyclase, which binds and activates substrate GGPP with a three-metal ion cluster. The N-terminal domain and a third insertion domain together adopt the fold of a vestigial class II terpenoid cyclase |
