Key Laboratories of Plant Design and Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2024 Mar 15;15(1):2339. doi: 10.1038/s41467-024-46583-3.
Taxol is a widely-applied anticancer drug that inhibits microtubule dynamics in actively replicating cells. Although a minimum 19-step biosynthetic pathway has been proposed and 16 enzymes likely involved have been characterized, stepwise biosynthetic reactions from the well-characterized di-oxygenated taxoids to Taxol tetracyclic core skeleton are yet to be elucidated. Here, we uncover the biosynthetic pathways for a few tri-oxygenated taxoids via confirming the critical reaction order of the second and third hydroxylation steps, unearth a taxoid 9α-hydroxylase catalyzing the fourth hydroxylation, and identify CYP725A55 catalyzing the oxetane ester formation via a cascade oxidation-concerted acyl rearrangement mechanism. After identifying a acetyltransferase catalyzing the formation of C7-OAc, the pathway producing the highly-oxygenated 1β-dehydroxybaccatin VI with the Taxol tetracyclic core skeleton is elucidated and its complete biosynthesis from taxa-4(20),11(12)-diene-5α-ol is achieved in an engineered yeast. These systematic studies lay the foundation for the complete elucidation of the biosynthetic pathway of Taxol.
紫杉醇是一种广泛应用的抗癌药物，能够抑制活跃复制细胞中的微管动态。虽然已经提出了一个最少 19 步的生物合成途径，并且已经鉴定了 16 种可能涉及的酶，但从结构明确的双氧化紫杉烷到紫杉醇四环核心骨架的逐步生物合成反应尚未阐明。在这里，我们通过确认第二和第三步羟化反应的关键反应顺序，揭示了一些三氧化紫杉烷的生物合成途径，发现了一种催化第四步羟化的紫杉烷 9α-羟化酶，并通过级联氧化协同酰基重排机制鉴定了 CYP725A55 催化氧杂环丁烷酯形成。在鉴定出催化 C7-OAc 形成的乙酰基转移酶后，阐明了具有紫杉醇四环核心骨架的高氧化 1β-去羟基巴卡丁 VI 的生成途径，并在工程酵母中实现了从紫杉烷-4(20),11(12)-二烯-5α-醇到该化合物的完全生物合成。这些系统研究为紫杉醇生物合成途径的完全阐明奠定了基础。
