Shinozaki Junichi, Shibuya Masaaki, Masuda Kazuo, Ebizuka Yutaka
Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
FEBS Lett. 2008 Jan 23;582(2):310-8. doi: 10.1016/j.febslet.2007.12.023. Epub 2007 Dec 26.
Ferns are the most primitive vascular plants. The phytosterols of ferns are the same as those of higher plants, but they produce characteristic triterpenes. The most distinct feature is the lack of oxygen functionality at C-3, suggesting that the triterpenes of ferns may be biosynthesized by direct cyclization of squalene. To obtain some insights into the molecular bases for the biosynthesis of triterpenes in ferns, we cloned ACX, an oxidosqualene cyclase homologue, encoding a cycloartenol synthase (CAS) and ACH, a squalene cyclase homologue, encoding a 22-hydroxyhopane synthase from Adiantum capillus-veneris. Phylogenetic analysis revealed that ACH is located in the cluster of bacterial SCs, while ACX is in the cluster of higher plant CASs.
蕨类植物是最原始的维管植物。蕨类植物的植物甾醇与高等植物的相同，但它们会产生特征性的三萜类化合物。最显著的特征是C-3位缺乏氧官能团，这表明蕨类植物的三萜类化合物可能是由角鲨烯直接环化生物合成的。为了深入了解蕨类植物中三萜类化合物生物合成的分子基础，我们克隆了ACX（一种氧化角鲨烯环化酶同源物，编码环阿屯醇合酶（CAS））和ACH（一种角鲨烯环化酶同源物，编码来自铁线蕨的22-羟基藿烷合酶）。系统发育分析表明，ACH位于细菌鲨烯环化酶的聚类中，而ACX则位于高等植物CAS的聚类中。
