Functional Characterization of Three Diterpene Synthases Responsible for Tetracyclic Diterpene Biosynthesis in <i>Scoparia dulcis</i>
2022
Jung-Bum Lee | Tomoya Ohmura | Yoshimi Yamamura
<i>Scoparia dulcis</i> produces unique biologically active diterpenoids such as scopadulcic acid B (SDB). They are biosynthesized from geranylgeranyl diphosphate (GGPP) via <i>syn</i>-copalyl diphosphate (<i>syn</i>-CPP) and scopadulanol as an important key intermediate. In this paper, we functionally characterized three diterpene synthases, SdCPS2, SdKSL1 and SdKSL2, from <i>S. dulcis.</i> The SdCPS2 catalyzed a cyclization reaction from GGPP to <i>syn-</i>CPP, and SdKSL1 did from <i>syn-</i>CPP to scopadulan-13α-ol. On the other hand, SdKSL2 was found to incorporate a non-sense mutation at 682. Therefore, we mutated the nucleotide residue from A to G in SdKSL2 to produce SdKSL2mut, and it was able to recover the catalytic function from <i>syn</i>-CPP to <i>syn</i>-aphidicol-16-ene, the precursor to scopadulin. From our results, SdCPS2 and SdKSL1 might be important key players for SDB biosynthesis in <i>S. dulcis</i>.
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