Muangphrom Paskorn, Seki Hikaru, Suzuki Munenori, Komori Aya, Nishiwaki Mika, Mikawa Ryota, Fukushima Ery Odette, Muranaka Toshiya
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871 Japan.
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871 Japan KNC Laboratories Co., Ltd., 3-2-34 Takatsukadai, Nishi-ku, Kobe, Hyogo, 651-2271 Japan.
Plant Cell Physiol. 2016 Aug;57(8):1678-88. doi: 10.1093/pcp/pcw094. Epub 2016 Jun 7.
The production of artemisinin, the most effective antimalarial compound, is limited to Artemisia annua. Enzymes involved in artemisinin biosynthesis include amorpha-4,11-diene synthase (ADS), amorpha-4,11-diene 12-monooxygenase (CYP71AV1) and artemisinic aldehyde Δ(11)13 reductase (DBR2). Although artemisinin and its specific intermediates are not detected in other Artemisia species, we reported previously that CYP71AV1 and DBR2 homologs were expressed in some non-artemisinin-producing Artemisia plants. These homologous enzymes showed similar functions to their counterparts in A. annua and can convert fed intermediates into the following products along the artemisinin biosynthesis in planta These findings suggested a partial artemisinin-producing ability in those species. In this study, we examined genes highly homologous to ADS, the first committed gene in the pathway, in 13 Artemisia species. We detected ADS homologs in A. absinthium, A. kurramensis and A. maritima. We analyzed the enzymatic functions of all of the ADS homologs after obtaining their cDNA. We found that the ADS homolog from A. absinthium exhibited novel activity in the cyclization of farnesyl pyrophosphate (FPP) to koidzumiol, a rare natural sesquiterpenoid. Those from A. kurramensis and A. maritima showed similar, but novel, activities in the cyclization of FPP to (+)-α-bisabolol. The unique functions of the novel sesquiterpene synthases highly homologous to ADS found in this study could provide insight into the molecular basis of the exceptional artemisinin-producing ability in A. annua.
青蒿素是最有效的抗疟化合物，其生产仅限于黄花蒿。参与青蒿素生物合成的酶包括紫穗槐-4,11-二烯合酶（ADS）、紫穗槐-4,11-二烯12-单加氧酶（CYP71AV1）和青蒿醛Δ(11)13还原酶（DBR2）。虽然在其他蒿属植物中未检测到青蒿素及其特定中间体，但我们之前报道过CYP71AV1和DBR2同源物在一些不产青蒿素的蒿属植物中表达。这些同源酶与其在黄花蒿中的对应物具有相似功能，并且可以在植物中将添加的中间体沿着青蒿素生物合成途径转化为后续产物。这些发现表明这些物种具有部分青蒿素生产能力。在本研究中，我们检测了13种蒿属植物中与该途径中第一个关键基因ADS高度同源的基因。我们在苦艾、库拉索蒿和滨海蒿中检测到了ADS同源物。在获得它们的cDNA后，我们分析了所有ADS同源物的酶功能。我们发现苦艾中的ADS同源物在将法尼基焦磷酸（FPP）环化生成罕见的天然倍半萜类化合物小泉醇方面表现出新颖的活性。库拉索蒿和滨海蒿中的ADS同源物在将FPP环化生成(+)-α-红没药醇方面表现出相似但新颖的活性。本研究中发现的与ADS高度同源的新型倍半萜合酶的独特功能，可为深入了解黄花蒿独特的青蒿素生产能力的分子基础提供线索。
