Several Boraginaceae plants produce biologically active red naphthoquinone pigments, derivatives of the enantiomers shikonin and alkannin, which vary in acyl groups on their side chains. Compositions of shikonin/alkannin derivatives vary in plant species, but the mechanisms generating the diversity of shikonin/alkannin derivatives are largely unknown. This study describes the identification and characterization of two BAHD acyltransferases, shikonin O-acyltransferase (LeSAT1) and alkannin O-acyltransferase (LeAAT1), from Lithospermum erythrorhizon, a medicinal plant in the family Boraginaceae that primarily produces the shikonin/alkannin derivatives acetylshikonin and β-hydroxyisovalerylshikonin. Enzyme assays using Escherichia coli showed that the acylation activity of LeSAT1 was specific to shikonin, whereas the acylation activity of LeAAT1 was specific to alkannin. Both enzymes recognized acetyl-CoA, isobutyryl-CoA, and isovaleryl-CoA as acyl donors to produce their corresponding shikonin/alkannin derivatives, with both enzymes showing the highest activity for acetyl-CoA. These findings were consistent with the composition of shikonin/alkannin derivatives in intact L. erythrorhizon plants and cell cultures. Genes encoding both enzymes were preferentially expressed in the roots and cell cultures in the dark in pigment production medium M9, conditions associated with shikonin/alkannin production. These results indicated that LeSAT1 and LeAAT1 are enantiomer-specific acyltransferases that generate various shikonin/alkannin derivatives.

几种紫草科植物产生具有生物活性的红色萘醌颜料，这是对映体紫草素和紫草素的衍生物，其侧链上的酰基有所不同。紫草素/紫草素衍生物的组成因植物种类而异，但产生紫草素/紫草素衍生物多样性的机制很大程度上未知。本研究描述了两种 BAHD 酰基转移酶的鉴定和表征，即紫草素 O-酰基转移酶 (LeSAT1) 和紫草素 O-酰基转移酶 (LeAAT1)，它们来自紫草，紫草科药用植物，主要​​产生紫草素/紫草素衍生物乙酰紫草素和β -羟基异戊酰紫草素。使用大肠杆菌的酶测定表明，LeSAT1 的酰化活性对紫草素具有特异性，而 LeAAT1 的酰化活性对紫草素具有特异性。两种酶均将乙酰辅酶 A、异丁酰辅酶 A 和异戊酰辅酶 A 识别为酰基供体，以产生相应的紫草素/紫草素衍生物，两种酶对乙酰辅酶 A 表现出最高的活性。这些发现与完整紫草中紫草素/紫草素衍生物的组成一致。红根植物和细胞培养物。编码这两种酶的基因优先在黑暗的色素生产培养基 M9（与紫草素/紫草素生产相关的条件）中的根和细胞培养物中表达。这些结果表明LeSAT1和LeAAT1是对映体特异性酰基转移酶，可产生各种紫草素/紫草素衍生物。