Biosynthesis of dillapiole/apiole in dill (Anethum graveolens): characterization of regioselective phenylpropene O-methyltransferase
Biosynthesis of dillapiole/apiole in dill (Anethum graveolens): characterization of regioselective phenylpropene O-methyltransferase
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莳萝 (Anethumgravolens) 中 dillapiole/apiole 的生物合成：区域选择性苯丙烯 O-甲基转移酶的表征
DOI：
10.1111/tpj.16068
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Shin-ichi Ozaki
中科院分区：
文献类型：
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作者：
Takao Koeduka;Bunta Watanabe;Konomi Shirahama;Masaru Nakayasu;Shiro Suzuki;Takumi Furuta;Hideyuki Suzuki;Kenji Matsui;Tomoyuki Kosaka;Shin-ichi Ozaki
苯丙烯挥发物dillapiole和apiole赋予莳萝（Anethum graveolens）杂草的特征香气之一。然而，很少有研究已经进行了调查的挥发性化合物的化学组成，从不同的发展阶段和植物部分的A。graveolens。在这项研究中，我们研究了挥发性苯丙烯，包括莳萝，在莳萝植物的不同发育阶段的分布。我们观察到，年轻的莳萝幼苗积累高水平的莳萝和芹菜，而一个可以忽略不计的比例被发现在开花植物和干种子。基于转录组学和与苯丙烯生物合成基因的共表达方法，我们鉴定了编码S-腺苷-L-甲硫氨酸依赖性O-甲基转移酶1（AgOMT 1）的dill cDNA，该酶可以通过邻羟基的甲基化将6-和2-羟基肉豆蔻酸分别转化为dillapiole和apiole。AgOMT 1蛋白对6-羟基肉豆蔻酸的表观Km值为3.5 μ m，与茴香O-甲基转移酶（PaAIMT 1）有75%的相同性，PaAIMT 1可以通过苯环对位羟基的甲基化将异丁香酚转化为甲基异丁香酚。AgOMT 1对6-hydroxymyristicin有较强的选择性，而PaAIMT 1对异丁香酚有较强的选择性。体外诱变实验表明，仅取代几个残基就能显著影响这些酶的底物特异性。属于伞形科的其他植物含有与AgOMT 1高度相似的同源O-甲基转移酶（OMT）蛋白，将6-羟基肉豆蔻酸转化为dillapiole。我们的研究结果表明，具有邻位甲基化活性的蜜蜂苯丙烯OMT独立于其他植物的苯丙烯OMT进化，并且AgOMT 1和PaAIMT 1的酶功能最近出现分歧。
The phenylpropene volatiles dillapiole and apiole impart one of the characteristic aromas of dill (Anethum graveolens) weeds. However, very few studies have been conducted to investigate the chemical composition of volatile compounds from different developmental stages and plant parts ofA. graveolens. In this study, we examined the distribution of volatile phenylpropenes, including dillapiole, in dill plants at various developmental stages. We observed that young dill seedlings accumulate high levels of dillapiole and apiole, whereas a negligible proportion was found in the flowering plants and dry seeds. Based on transcriptomics and co‐expression approaches with phenylpropene biosynthesis genes, we identified dill cDNA encodingS‐adenosyl‐L‐methionine‐dependentO‐methyltransferase 1 (AgOMT1), an enzyme that can convert 6‐ and 2‐hydroxymyristicin to dillapiole and apiole, respectively, via the methylation of theortho‐hydroxy group. The AgOMT1 protein shows an apparentKmvalue of 3.5 μmfor 6‐hydroxymyristicin and is 75% identical to the anise (Pimpinella anisum)O‐methyltransferase (PaAIMT1) that can convert isoeugenol to methylisoeugenol via methylation of the hydroxy group at thepara‐position of the benzene ring. AgOMT1 showed a preference for 6‐hydroxymyristicin, whereas PaAIMT1 displayed a large preference for isoeugenol.In vitromutagenesis experiments demonstrated that substituting only a few residues can substantially affect the substrate specificity of these enzymes. Other plants belonging to the Apiaceae family contained homologousO‐methyltransferase (OMT) proteins highly similar to AgOMT1, converting 6‐hydroxymyristicin to dillapiole. Our results indicate that apiaceous phenylpropene OMTs withortho‐methylating activity evolved independently of phenylpropene OMTs of other plants and the enzymatic function of AgOMT1 and PaAIMT1 diverged recently.