Department of Plant Biology, University of California - Davis, Davis, California, 95616, USA.
Genome Center, University of California - Davis, Davis, California, 95616, USA.
Plant J. 2021 Nov;108(4):1053-1068. doi: 10.1111/tpj.15492. Epub 2021 Sep 24.
Specialized diterpenoid metabolites are important mediators of plant-environment interactions in monocot crops. To understand metabolite functions in plant environmental adaptation that ultimately can enable crop improvement strategies, a deeper knowledge of the underlying species-specific biosynthetic pathways is required. Here, we report the genomics-enabled discovery of five cytochrome P450 monooxygenases (CYP71Z25-CYP71Z29) that form previously unknown furanoditerpenoids in the monocot bioenergy crop Panicum virgatum (switchgrass). Combinatorial pathway reconstruction showed that CYP71Z25-CYP71Z29 catalyze furan ring addition directly to primary diterpene alcohol intermediates derived from distinct class II diterpene synthase products. Transcriptional co-expression patterns and the presence of select diterpenoids in switchgrass roots support the occurrence of P450-derived furanoditerpenoids in planta. Integrating molecular dynamics, structural analysis and targeted mutagenesis identified active site determinants that contribute to the distinct catalytic specificities underlying the broad substrate promiscuity of CYP71Z25-CYP71Z29 for native and non-native diterpenoids.
特种二萜类代谢物是单子叶作物中植物与环境相互作用的重要介质。为了了解代谢物在植物环境适应中的功能，最终实现作物改良策略，需要更深入地了解特定于物种的潜在生物合成途径。在这里，我们报告了基于基因组学的发现，即五个细胞色素 P450 单加氧酶（CYP71Z25-CYP71Z29）在单子叶生物能源作物柳枝稷（芒草）中形成以前未知的呋喃二萜类化合物。组合途径重建表明，CYP71Z25-CYP71Z29 直接催化呋喃环添加到源自不同类 II 二萜合酶产物的主要二萜醇中间体。转录共表达模式和柳枝稷根中选择的二萜类化合物的存在支持 P450 衍生的呋喃二萜类化合物在体内的发生。整合分子动力学、结构分析和靶向诱变鉴定出活性位点决定因素，这些因素有助于 CYP71Z25-CYP71Z29 对天然和非天然二萜类化合物具有广泛底物混杂性的独特催化特异性。
