Preisig-Müller R, Gnau P, Kindl H
Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
Arch Biochem Biophys. 1995 Feb 20;317(1):201-7. doi: 10.1006/abbi.1995.1154.
Tricyclic 9,10-dihydrophenanthrenes originate from phenylpropane derivatives by chain elongation and cyclization according to the polyacetate rule. Bibenzyls are bicyclic intermediates, and O-methylation is a prerequisite for their conversion into dihydrophenanthrenes. cDNA clones encoding bibenzyl synthases and S-adenosylhomocysteine hydrolase of the orchid Phalaenopsis sp. were isolated from a cDNA library representing the stage of elicitor-induced plants. The deduced amino acid sequences of two clones, pBibSy811 and pBibSy212, indicated that we obtained two full-length sequences of bibenzyl synthases characterized by their homology to stilbene synthases previously investigated. That indeed bibenzyl synthase cDNAs rather than a homologous stilbene synthase cDNA or chalcone synthase cDNA have been isolated was demonstrated by expression of two enzymatically active bibenzyl synthase proteins in Escherichia coli. These proteins showed virtually the same selectivity towards m-hydroxyphenylpropionyl-CoA as substrate as the enzyme isolated from orchid plants. In young sterile Phalaenopsis plants, the formation of both bibenzyl synthase mRNAs and S-adenosylhomocysteine hydrolase mRNAs was increased upon elicitation more than 100-fold. The time courses of gene expression exhibited transient profiles, reaching maximum mRNA levels 20 h after onset of fungal infection followed by a rapid decline to 40 h.
三环9,10 - 二氢菲根据聚乙酸酯规则通过链延长和环化作用从苯丙烷衍生物衍生而来。联苄是双环中间体，O - 甲基化是它们转化为二氢菲的先决条件。从代表激发子诱导植物阶段的cDNA文库中分离出编码蝴蝶兰联苄合酶和S - 腺苷同型半胱氨酸水解酶的cDNA克隆。两个克隆pBibSy811和pBibSy212推导的氨基酸序列表明，我们获得了两个联苄合酶的全长序列，其特征是与先前研究的芪合酶具有同源性。在大肠杆菌中表达两种具有酶活性的联苄合酶蛋白证明，确实分离出了联苄合酶cDNA，而不是同源的芪合酶cDNA或查尔酮合酶cDNA。这些蛋白质对间羟基苯丙酰辅酶A作为底物的选择性与从兰花植物中分离的酶几乎相同。在幼小的无菌蝴蝶兰植物中，激发后联苄合酶mRNA和S - 腺苷同型半胱氨酸水解酶mRNA的形成增加了100多倍。基因表达的时间进程呈现出瞬时模式，在真菌感染开始后20小时达到最大mRNA水平，随后在40小时迅速下降。
