Department of Chemical and Biomolecular Engineering, and #Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095.
J Am Chem Soc. 2014 Mar 19;136(11):4426-36. doi: 10.1021/ja500881e. Epub 2014 Mar 11.
Fumagillin (1), a meroterpenoid from Aspergillus fumigatus, is known for its antiangiogenic activity due to binding to human methionine aminopeptidase 2. 1 has a highly oxygenated structure containing a penta-substituted cyclohexane that is generated by oxidative cleavage of the bicyclic sesquiterpene β-trans-bergamotene. The chemical nature, order, and biochemical mechanism of all the oxygenative tailoring reactions has remained enigmatic despite the identification of the biosynthetic gene cluster and the use of targeted-gene deletion experiments. Here, we report the identification and characterization of three oxygenases from the fumagillin biosynthetic pathway, including a multifunctional cytochrome P450 monooxygenase, a hydroxylating nonheme-iron-dependent dioxygenase, and an ABM family monooxygenase for oxidative cleavage of the polyketide moiety. Most significantly, the P450 monooxygenase is shown to catalyze successive hydroxylation, bicyclic ring-opening, and two epoxidations that generate the sesquiterpenoid core skeleton of 1. We also characterized a truncated polyketide synthase with a ketoreductase function that controls the configuration at C-5 of hydroxylated intermediates.
来自烟曲霉的呋喃并[2,3-b]色烯（1）是一种生源杂萜，由于与人甲硫氨酸氨肽酶 2 结合而具有抗血管生成活性。1 具有高度氧化的结构，包含一个通过双环倍半萜 β-反式佛手柑烯的氧化裂解生成的五取代环己烷。尽管已经鉴定了生物合成基因簇并使用了靶向基因缺失实验，但所有氧化修饰反应的化学性质、顺序和生化机制仍然是个谜。在这里，我们报告了三种来自呋喃并[2,3-b]色烯生物合成途径的加氧酶的鉴定和表征，包括多功能细胞色素 P450 单加氧酶、羟化非血红素依赖性双加氧酶和用于氧化裂解聚酮部分的 ABM 家族单加氧酶。最重要的是，细胞色素 P450 单加氧酶被证明能够催化连续的羟化、双环开环和两个环氧化反应，从而生成 1 的倍半萜核心骨架。我们还表征了一种具有酮还原酶功能的截断聚酮合酶，它控制羟化中间体 C-5 的构型。
