Abstract

Labdane-related diterpenoids (LRDs) in fungi are a pharmaceutically important, but underexplored family of natural products. In the biosynthesis of fungal LRDs, bifunctional terpene cyclases (TCs) consisting of αβγ domains are generally used to synthesize the polycyclic skeletones of LRDs. Herein, we conducted genome mining of LRDs in our fungal genome database and identified a unique pair of TCs, AsPS and AsCPS, in the fungus Arthrinium sacchari. AsPS consists of catalytically active α and inactive β domains, whereas AsCPS contains βγ domains and a truncated α domain. Heterologous expression in Aspergillus oryzae and biochemical characterization of recombinant proteins demonstrated that AsCPS synthesized copalyl diphosphate and that AsPS then converted it to (−)-sandaracopimaradiene. Since AsPS and AsCPS have distinct domain organizations from those of known fungal TCs and are likely generated through fusion or loss of catalytic domains, our findings provide insight into the evolution of TCs in fungi.

Beilstein J. Org. Chem. 2024, 20, 714–720. doi:10.3762/bjoc.20.65

摘要

真菌中的拉丹丹相关二萜类化合物 (LRD) 是一类具有重要药学意义但尚未得到充分开发的天然产物家族。在真菌LRDs的生物合成中，通常使用由αβγ结构域组成的双功能萜烯环化酶（TCs）来合成LRDs的多环骨架。在此，我们对真菌基因组数据库中的 LRD 进行了基因组挖掘，并在真菌Arthrinium sacchari中鉴定了一对独特的 TC，AsPS 和 AsCPS 。 AsPS 由催化活性 α 和非活性 β 结构域组成，而 AsCPS 包含 βγ 结构域和截短的 α 结构域。米曲霉中的异源表达和重组蛋白的生化表征表明，AsCPS 合成二磷酸柯巴基，然后将其转化为 (-)-sandaracopimaradiene。由于 AsPS 和 AsCPS 具有与已知真菌 TC 不同的结构域组织，并且可能是通过催化结构域的融合或丢失而产生的，因此我们的研究结果提供了对真菌中 TC 进化的深入了解。

贝尔斯坦 J. 组织。化学。 2024, 20, 714–720。 doi:10.3762/bjoc.20.65