An Alternative Pathway for Formononetin Biosynthesis in Pueraria lobata.
An Alternative Pathway for Formononetin Biosynthesis in Pueraria lobata.
复制标题
葛根芒柄花素生物合成的替代途径
DOI：
10.3389/fpls.2016.00861
复制
发表时间：
2016
影响因子：
5.6
通讯作者：
Zhang Y
中科院分区：
文献类型：
--
作者：
Li J;Li C;Gou J;Wang X;Fan R;Zhang Y
O-甲基化是葛根异黄酮代谢的重要拖尾过程，但其分子机制尚不清楚。这篇手稿描述了这一过程中涉及的关键O-甲基转移酶(OMTs)的挖掘。利用我们先前构建的P.lobata转录组，对OMT候选基因进行了搜索和广泛的分析，并通过在酵母、大肠杆菌或大豆毛状根中的表达来研究它们的功能。在这里，我们报告了在P.lobata(命名为PlOMT9)中负责芒柄花素产生的关键OMT基因的鉴定。PlOMT9主要作为异黄酮特异性的4‘-O-甲基转移酶发挥作用，尽管它与异黄酮7-O-甲基转移酶有很高的序列同源性。此外，与以前报道的在异黄酮期催化芒柄花素生物合成的4‘-O-甲基化反应不同，PlOMT9在异黄酮级水平上执行这一修饰步骤，使用大豆苷元而不是2，7，4’-三羟基-异黄酮作底物。基因表达分析和代谢物图谱支持其在P.lobata中的作用。利用转基因毛状根系统，在体内进一步证实了PlOMT9在芒柄花素生物合成中的作用。
The O-methylation is an important tailing process in Pueraria lobata isoflavone metabolism, but the molecular mechanism governing it remains not elucidated. This manuscript describes the mining of key O-methyltransferases (OMTs) involved in the process. Using our previously constructed P. lobata transcriptome, the OMT candidates were searched, extensively analyzed, and their functions were investigated by expression in yeast, Escherichia coli, or Glycine max hairy roots. Here, we report the identification of the key OMT gene responsible for formononetin production in P. lobata (designated as PlOMT9). PlOMT9 primarily functions as an isoflavone-specific 4′-O-methyltransferase, although it shows high sequence identities with isoflavone 7-O-methyltransferases. Moreover, unlike the previously reported OMTs that catalyze the 4′-O-methylation for formononetin biosynthesis at the isoflavanone stage, PlOMT9 performs this modifying step at the isoflavone level, using daidzein rather than 2,7,4′-trihydroxy-isoflavanone as the substrate. Gene expression analyses and metabolite profiling supported its proposed roles in P. lobata. Using the system of transgenic G. max hairy roots, the role of PlOMT9 in the biosynthesis of formononetin was further demonstrated in vivo.