The Genetic Basis of Constitutive and Herbivore-Induced ESP-Independent Nitrile Formation in Arabidopsis
The Genetic Basis of Constitutive and Herbivore-Induced ESP-Independent Nitrile Formation in Arabidopsis
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DOI：
10.1104/pp.108.130732
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发表时间：
2009-01-01
期刊：
影响因子：
7.4
通讯作者：
Wittstock, Ute
中科院分区：
文献类型：
--
作者：
Burow, Meike;Losansky, Anja;Wittstock, Ute
硫代葡萄糖苷是一组硫代葡萄糖苷，是在紫茎泽兰目中发现的活化化学防御的组分。植物组织损伤导致芥子油苷被称为黑芥子酶的内源性硫代葡萄糖苷酶水解。糖苷配基的自发重排产生对许多生物有毒的活性异硫氰酸酯。在指定蛋白质的存在下，替代产品，即epithionitriles，简单的腈，和具有不同的生物活性的硫氰酸酯，形成在异硫氰酸酯的费用。最近，简单腈被认为在植物-昆虫相互作用中具有独特的功能。在这里，我们表明，简单的腈形成在拟南芥（拟南芥）生态型哥伦比亚-0莲座叶增加，响应草食动物，这种增加是独立的已知epithiopspecifier蛋白（ESP）。我们结合系统发育分析，筛选拟南芥突变体，重组蛋白的表征，和表达的数量性状位点定位，以确定一个基因编码的腈特异蛋白（NSP）负责组成和草食动物诱导的简单腈形成哥伦比亚-0莲座叶。AtNSP 1是五个拟南芥ESP同源物之一，促进简单的腈，但不是epithionitrile或硫氰酸盐，形成。这些同源物中的四个具有一个或两个凝集素样jacalin结构域，其与推定的拟南芥黑芥子酶结合蛋白MBP 1和MBP 2的jacalin结构域共享共同的祖先。第六个ESP同源物缺乏特异性活性，可能代表具有不同生化功能的基因家族的祖先。通过阐明简单腈形成的遗传和生化基础，我们的研究为复杂植物防御系统中代谢多样性的进化提供了新的见解。
Glucosinolates are a group of thioglucosides that are components of an activated chemical defense found in the Brassicales. Plant tissue damage results in hydrolysis of glucosinolates by endogenous thioglucosidases known as myrosinases. Spontaneous rearrangement of the aglucone yields reactive isothiocyanates that are toxic to many organisms. In the presence of specifier proteins, alternative products, namely epithionitriles, simple nitriles, and thiocyanates with different biological activities, are formed at the expense of isothiocyanates. Recently, simple nitriles were recognized to serve distinct functions in plant-insect interactions. Here, we show that simple nitrile formation in Arabidopsis (Arabidopsis thaliana) ecotype Columbia-0 rosette leaves increases in response to herbivory and that this increase is independent of the known epithiospecifier protein (ESP). We combined phylogenetic analysis, a screen of Arabidopsis mutants, recombinant protein characterization, and expression quantitative trait locus mapping to identify a gene encoding a nitrile-specifier protein (NSP) responsible for constitutive and herbivore-induced simple nitrile formation in Columbia-0 rosette leaves. AtNSP1 is one of five Arabidopsis ESP homologues that promote simple nitrile, but not epithionitrile or thiocyanate, formation. Four of these homologues possess one or two lectin-like jacalin domains, which share a common ancestry with the jacalin domains of the putative Arabidopsis myrosinase-binding proteins MBP1 and MBP2. A sixth ESP homologue lacked specifier activity and likely represents the ancestor of the gene family with a different biochemical function. By illuminating the genetic and biochemical bases of simple nitrile formation, our study provides new insights into the evolution of metabolic diversity in a complex plant defense system.