The evolution of natural product biosynthetic pathways can be envisioned to occur via a number of mechanisms. In the present study we provide evidence that latent plasticity plays a role in such metabolic evolution. In particular, rice (Oryza sativa) produces both ent- and syn-CPP (copalyl diphosphate), which are substrates for downstream diterpene synthases. In the present paper we report that several members of this enzymatic family exhibit dual reactivity with some pairing of ent-, syn- or normal CPP stereochemistry. Evident plasticity was observed, as a previously reported ent-sandaracopimaradiene synthase also converts syn-CPP into syn-labda-8(17),12E,14-triene, which can be found in planta. Notably, normal CPP is not naturally found in rice. Thus the presence of diterpene synthases that react with this non-native metabolite reveals latent enzymatic/metabolic plasticity, providing biochemical capacity for utilization of such a novel substrate (i.e. normal CPP) which may arise during evolution, the implications of which are discussed.
天然产物生物合成途径的进化可通过多种机制实现。本研究提供的证据表明,潜在的可塑性在这种代谢进化中发挥了作用。特别是,水稻(Oryza sativa)同时产生ent-和syn-CPP(共聚二磷酸),它们是下游二萜合成酶的底物。在本文中,我们报告了该酶家族中的几个成员表现出了双重反应性,它们在ent-、syn-或正常 CPP 立体化学上有一些配对。我们观察到了明显的可塑性,因为之前报道的一种ent-sandaracopimaradiene合成酶也能将syn-CPP转化为syn-labda-8(17),12E,14-triene,这在植物体内也能发现。值得注意的是,水稻中并不天然存在正常的 CPP。因此,与这种非本地代谢物发生反应的二萜合成酶的存在揭示了潜在的酶/代谢可塑性,为利用这种可能在进化过程中产生的新型底物(即正常 CPP)提供了生化能力,其意义将在本文中讨论。