Identification of O-Methyltransferases Potentially Contributing to the Structural Diversity of 2-(2-Phenylethyl)chromones in Agarwood,Journal of Agricultural and Food Chemistry

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Identification of O-Methyltransferases Potentially Contributing to the Structural Diversity of 2-(2-Phenylethyl)chromones in Agarwood
Journal of Agricultural and Food Chemistry ( IF 5.7 ) Pub Date : 2024-06-03 , DOI: 10.1021/acs.jafc.4c02440
Bingbing Wang ₁ , Yan Hai ₁ , Le Zhang ₁ , Mingliang Zhang ₁ , Ning Ding ₁ , Jiangping Fan ₁ , Beibei Zhang ₁ , Zekun Zhang ₁ , Juan Wang ₁ , Xiaohui Wang ₁ , Jun Li ₁ , Pengfei Tu _{1,

2} , Xiao Liu ₁ , She-Po Shi ₁

Affiliation

2-(2-Phenylethyl)chromones (PECs) are the primary constituents responsible for the promising pharmacological activities and unique fragrance of agarwood. However, the O-methyltransferases (OMTs) involved in the formation of diverse methylated PECs have not been reported. In this study, we identified one Mg²⁺-dependent caffeoyl-CoA-OMT subfamily enzyme (AsOMT1) and three caffeic acid-OMT subfamily enzymes (AsOMT2–4) from NaCl-treated Aquilaria sinensis calli. AsOMT1 not only converts caffeoyl-CoA to feruloyl-CoA but also performs nonregioselective methylation at either the 6-OH or 7-OH position of 6,7-dihydroxy-PEC. On the other hand, AsOMT2–4 preferentially utilizes PECs as substrates to produce structurally diverse methylated PECs. Additionally, AsOMT2–4 also accepts nonPEC-type substrates such as caffeic acid and apigenin to generate methylated products. Protein structure prediction and site-directed mutagenesis revealed that residues of L313 and I318 in AsOMT3, as well as S292 and F313 in AsOMT4 determine the distinct regioselectivity of these two OMTs toward apigenin. These findings provide important biochemical evidence of the remarkable structural diversity of PECs in agarwood.

中文翻译：

沉香中可能有助于 2-(2-苯乙基)色酮结构多样性的 O-甲基转移酶的鉴定

2-(2-苯乙基)色酮 (PEC) 是沉香具有良好药理活性和独特香味的主要成分。然而， O-甲基转移酶（OMT）参与多种甲基化PEC的形成尚未见报道。在本研究中，我们从 NaCl 处理的沉香愈伤组织中鉴定出一种 Mg ²⁺依赖的咖啡酰辅酶 A-OMT 亚家族酶 (AsOMT1) 和三种咖啡酸-OMT 亚家族酶 (AsOMT2–4)。 AsOMT1 不仅将咖啡酰辅酶 A 转化为阿魏酰辅酶 A，而且还在 6,7-二羟基 -PEC 的 6-OH 或 7-OH 位置进行非区域选择性甲基化。另一方面，AsOMT2-4 优先利用 PEC 作为底物来产生结构多样的甲基化 PEC。此外，AsOMT2-4 还接受非 PEC 型底物（例如咖啡酸和芹菜素）以生成甲基化产物。蛋白质结构预测和定点诱变表明，AsOMT3 中的 L313 和 I318 残基以及 AsOMT4 中的 S292 和 F313 残基决定了这两种 OMT 对芹菜素的不同区域选择性。这些发现为沉香中 PEC 的显着结构多样性提供了重要的生化证据。

更新日期：2024-06-03

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