Noda Institute for Scientific Research, 399 Noda, Noda, Chiba 278-0037, Japan.
Chemical Biology Research Group, RIKEN CSRS, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Sci Rep. 2016 Sep 15;6:32865. doi: 10.1038/srep32865.
Esterified drimane-type sesquiterpene lactones such as astellolides display various biological activities and are widely produced by plants and fungi. Given their low homology to known sesquiterpene cyclases, the genes responsible for their biosynthesis have not been uncovered yet. Here, we identified the astellolide gene cluster from Aspergillus oryzae and discovered a novel sesquiterpene biosynthetic machinery consisting of AstC, AstI, and AstK. All these enzymes are annotated as haloacid dehalogenase-like hydrolases, whereas AstC also contains a DxDTT motif conserved in class II diterpene cyclases. Based on enzyme reaction analyses, we found that AstC catalysed the protonation-initiated cyclisation of farnesyl pyrophosphate into drimanyl pyrophosphate. This was successively dephosphorylated by AstI and AstK to produce drim-8-ene-11-ol. Moreover, we also identified and characterised a unique non-ribosomal peptide synthetase, AstA, responsible for esterifying aryl acids to drimane-type sesquiterpene lactones. In this study, we highlight a new biosynthetic route for producing sesquiterpene and its esterified derivative. Our findings shed light on the identification of novel sesquiterpenes via genome mining.
酯化型大根香叶型倍半萜内酯如阿替洛尔具有多种生物活性，广泛存在于植物和真菌中。鉴于它们与已知的倍半萜环化酶的同源性较低，其生物合成的相关基因尚未被发现。在这里，我们从米曲霉中鉴定出了阿替洛尔基因簇，并发现了一种由 AstC、AstI 和 AstK 组成的新型倍半萜生物合成机制。所有这些酶都被注释为卤酸脱卤酶样水解酶，而 AstC 还含有一个在 II 类二萜环化酶中保守的 DxDTT 基序。基于酶反应分析，我们发现 AstC 催化法呢基焦磷酸质子化引发的环化反应生成大根香叶基焦磷酸。然后 AstI 和 AstK 使它去磷酸化生成大根香叶-8-烯-11-醇。此外，我们还鉴定并表征了一个独特的非核糖体肽合成酶 AstA，它负责将芳基酸酯化到大根香叶型倍半萜内酯上。在这项研究中，我们强调了一种产生倍半萜及其酯化衍生物的新生物合成途径。我们的研究结果为通过基因组挖掘鉴定新型倍半萜提供了依据。
