Fig. 3

The structure and plasticity regions of plant MTPSs. The structure and plasticity regions of plant monoterpene synthases are based on the limonene synthases from Mentha spicata with substrate analog FGPP (PDB: 2ong) [45]. The N-terminal and C-terminal domains are shown in green and purple, respectively. The metal cofactors (Mn²⁺) are indicated in magenta, while the two metal-binding motifs (DDXXD and NSE/DTE motifs) are highlighted in red. The RR(X₈)W motif on the N-terminal domain is distinguished in lemon. The four plasticity regions (Reg1–4 corresponding to regions 1–4) are highlighted in orange, cyan, gray and yellow, respectively.