Lysine Decarboxylase Catalyzes the First Step of Quinolizidine Alkaloid Biosynthesis and Coevolved with Alkaloid Production in Leguminosae
Lysine Decarboxylase Catalyzes the First Step of Quinolizidine Alkaloid Biosynthesis and Coevolved with Alkaloid Production in Leguminosae
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DOI：
10.1105/tpc.112.095885
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发表时间：
2012-03-01
期刊：
影响因子：
11.6
通讯作者：
Yamazaki, Mami
中科院分区：
文献类型：
--
作者：
Bunsupa, Somnuk;Katayama, Kae;Yamazaki, Mami
喹啉嗪类生物碱是一类独特的植物生物碱，赖氨酸脱羧酶（LDC）是喹啉嗪类生物碱生物合成的第一步催化酶。利用差异转录筛选技术，从狭叶羽扇豆（Lupinus angustifolius）中分离到赖氨酸/鸟氨酸脱羧酶（L/ODC）的cDNA。我们还获得了L/ODC的cDNA从其他四个QA生产的植物，苦参，朝鲜松果菊，华，和洗礼。这些L/ODC在植物鸟氨酸脱羧酶家族中形成遗传学上不同的亚支。来自QA产生植物的重组L/ODC优先或同等地催化L-赖氨酸和L-鸟氨酸的脱羧。L.通过在拟南芥中瞬时表达与绿色荧光蛋白N端融合的La-L/ODC融合蛋白，发现La-L/ODC（La-L/ODC）定位于叶绿体中。转基因烟草（烟草）悬浮细胞和毛状根产生增强水平的尸胺衍生的生物碱，和转基因拟南芥植物表达（La-L/ODC）产生增强水平的尸胺，表明这种酶参与赖氨酸脱羧形成尸胺。定点突变和蛋白质建模研究揭示了优先LDC活性的结构基础，表明L/ODC在QA生产植物中的进化意义。
Lysine decarboxylase (LDC) catalyzes the first-step in the biosynthetic pathway of quinolizidine alkaloids (QAs), which form a distinct, large family of plant alkaloids. A cDNA of lysine/ornithine decarboxylase (L/ODC) was isolated by differential transcript screening in QA-producing and nonproducing cultivars of Lupinus angustifolius. We also obtained L/ODC cDNAs from four other QA-producing plants, Sophora flavescens, Echinosophora koreensis, Thermopsis chinensis, and Baptisia australis. These L/ODCs form a phylogenetically distinct subclade in the family of plant ornithine decarboxylases. Recombinant L/ODCs from QA-producing plants preferentially or equally catalyzed the decarboxylation of L-lysine and L-ornithine. L. angustifolius L/ODC (La-L/ODC) was found to be localized in chloroplasts, as suggested by the transient expression of a fusion protein of La-L/ODC fused to the N terminus of green fluorescent protein in Arabidopsis thaliana. Transgenic tobacco (Nicotiana tabacum) suspension cells and hairy roots produced enhanced levels of cadaverine-derived alkaloids, and transgenic Arabidopsis plants expressing (La-L/ODC) produced enhanced levels of cadaverine, indicating the involvement of this enzyme in lysine decarboxylation to form cadaverine. Site-directed mutagenesis and protein modeling studies revealed a structural basis for preferential LDC activity, suggesting an evolutionary implication of L/ODC in the QA-producing plants.