A cluster of genes encodes the two types of chalcone isomerase involved in the biosynthesis of general flavonoids and legume-specific 5-deoxy(iso)flavonoids in Lotus japonicus
A cluster of genes encodes the two types of chalcone isomerase involved in the biosynthesis of general flavonoids and legume-specific 5-deoxy(iso)flavonoids in Lotus japonicus
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DOI：
10.1104/pp.004820
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发表时间：
2003-03-01
期刊：
影响因子：
7.4
通讯作者：
Ayabe, S
中科院分区：
文献类型：
--
作者：
Shimada, N;Aoki, T;Ayabe, S
豆科植物产生的5-脱氧黄酮和5-脱氧甘草酸在豆科植物与微生物的相互作用中发挥重要作用。与查尔酮聚酮还原酶和细胞色素P450 2-羟基异黄烷酮合酶一起，豆科植物的查尔酮异构酶（CHI）在这些具有生理生态活性的黄酮类化合物的构建中是基本的。尽管非豆科植物的CHI仅将6 ′-羟基查耳酮异构化为5-羟基黄烷酮（具有此功能的CHI称为I型），但豆科植物的CHI将6 ′-脱氧查耳酮和6 ′-羟基查耳酮分别转化为5-脱氧黄烷酮和5-羟基黄烷酮（称为II型）。在这项研究中，我们从模式豆科植物百脉根中分离出多个CHI cDNA（cCHI 1-cCHI 3）。与以前的观察结果相反，CHI 2的氨基酸序列与非豆科CHIs高度同源，而CHI 1和CHI 3是常规豆科类型。此外，基因组序列分析表明，四个CHI基因（CHI 1 -3和一个推定的基因，CHI 4）形成一个串联簇内15 kb。用在大肠杆菌中表达的重组CHI进行的生化分析证实，CHI 1和CHI 3是II型CHI，并且CHI 2是I型CHI。这两种类型的CHI的发生可能是常见的豆科植物，它被认为是从祖先CHI进化的基因复制和II型CHI开始产生5-脱氧（异）黄酮沿着成立的豆科植物。
Leguminous plants produce 5-deoxyflavonoids and 5-deoxyisoflavonoids that play essential roles in legume-microbe interactions. Together with chalcone polyketide reductase and cytochrome P450 2-hydroxyisoflavanone synthase, the chalcone isomerase (CHI) of leguminous plants is fundamental in the construction of these ecophysiologically active flavonoids. Although CHIs of nonleguminous plants isomerize only 6'-hydroxychalcone to 5-hydroxyflavanone (CHIs with this function are referred to as type I), leguminous CHIs convert both 6'-deoxychalcone and 6'-hydroxychalcone to 5-deoxyflavanone and 5-hydroxyflavanone, respectively (referred to as type II). In this study, we isolated multiple CHI cDNAs (cCHI1-cCHI3) from a model legume, Lotus japonicus. In contrast to previous observations, the amino acid sequence of CHI2 was highly homologous to nonleguminous CHIs, whereas CHI1 and CHI3 were the conventional leguminous type. Furthermore, genome sequence analysis revealed that four CHI genes (CHI1-3 and a putative gene, CHI4) form a tandem cluster within 15 kb. Biochemical analysis with recombinant CHIs expressed in Escherichia coli confirmed that CHI1 and CHI3 are type II CHIs and that CHI2 is a type I CHI. The occurrence of both types of CHIs is probably common in leguminous plants, and it was suggested that type II CHIs evolved from an ancestral CHI by gene duplication and began to produce 5-deoxy(iso)flavonoids along with the establishment of the Fabaceae.