Furanocoumarins are defense molecules mainly described in four plant families that are phylogenetically distant. Molecular characterization of the biosynthetic pathway has been started for many years in Apiaceae and Rutaceae. The results obtained thus far in Apiaceae indicated a major role of cytochromes P450 (P450s) in the CYP71 family. In the present work, we describe the importance of another subfamily of P450s, CYP82D, identified by using a deep analysis of the citrus (Rutaceae) genome and microarray database. CYP82D64 is able to hydroxylate xanthotoxin to generate 5-OH-xanthotoxin. Minor and limited amino acid changes in the CYP82D64 coding sequence between Citrus paradisi and Citrus hystrix provide the enzyme in the latter with the ability to hydroxylate herniarin, but with low efficiency. The kinetic constants of the enzyme are consistent with those of other enzymes of this type in plants and indicate that it may be the physiological substrate. The activity of the enzyme is identical to that of CYP71AZ6 identified in parsnip, showing possible evolutionary convergence between these two families of plants. It is highly possible that these molecules are derived from the synthesis of ubiquitous coumarins throughout the plant kingdom.

中文翻译：

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趋同进化导致柑橘类植物中呋喃香豆素的出现

呋喃香豆素是防御分子，主要存在于系统发育相距较远的四个植物科中。在伞形科和芸香科中，生物合成途径的分子表征已经开始多年。迄今为止在伞形科中获得的结果表明细胞色素 P450 (P450s) 在 CYP71 家族中的主要作用。在目前的工作中，我们描述了另一个 P450 亚家族 CYP82D 的重要性，该亚家族是通过对柑橘（芸香科）基因组和微阵列数据库的深入分析来确定的。CYP82D64 能够羟基化黄酮生成 5-OH-黄酮。Citrus paradisi 和 Citrus hystrix 之间的 CYP82D64 编码序列中的微小和有限的氨基酸变化为后者中的酶提供了羟基化herniarin 的能力，但效率低下。该酶的动力学常数与植物中其他此类酶的动力学常数一致，表明它可能是生理底物。该酶的活性与欧洲防风草中鉴定的 CYP71AZ6 的活性相同，表明这两个植物科之间可能存在进化趋同。这些分子极有可能来自整个植物界普遍存在的香豆素的合成。