Amrein Hans, Makart Stefan, Granado José, Shakya Roshani, Schneider-Pokorny Jana, Dudler Robert
Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
Mol Plant Microbe Interact. 2004 Jan;17(1):90-7. doi: 10.1094/MPMI.2004.17.1.90.
Strains of the phytopathogenic bacterium Pseudomonas syringae pv. syringae secrete a family of structurally closely related peptide derivatives dubbed syringolins, of which syringolin A is the major variant. The function of syringolins in the interaction of P. syringae pv. syringae with their host plants presently is unknown. It is hypothesized that they may constitute virulence factors. However, syringolins are determinants recognized and reacted to by nonhost plant species, and syringolin A has been shown to induce hypersensitive death of cells colonized by powdery mildew in wheat and, thus, to reprogram a compatible interaction into an incompatible one. Syringolin A is an unusual derivative of a tripeptide that contains a 12-membered ring consisting of the amino acids 5-methyl-4-amino-2-hexenoic acid and 3,4-dehydrolysine, two nonproteinogenic amino acids. Here we report the cloning, sequencing, and analysis of genes involved in the biosynthesis of syringolin A. The genes encode proteins consisting of modules typical for nonribosomal peptide synthetases and type I polyketide synthetases, as well as proteins likely involved in the transcriptional regulation of syringolin A biosynthesis and in syringolin A export. The structure and arrangement of the modules lead to the formulation of a model explaining the synthesis of the tripeptide, including the formation of the two nonproteinogenic amino acids in the ring structure of syringolin A.
植物致病细菌丁香假单胞菌丁香致病变种（Pseudomonas syringae pv. syringae）的菌株分泌一族结构密切相关的肽衍生物，称为丁香菌素，其中丁香菌素A是主要变体。目前尚不清楚丁香菌素在丁香假单胞菌丁香致病变种与其寄主植物相互作用中的功能。据推测，它们可能构成致病因子。然而，丁香菌素是被非寄主植物物种识别并产生反应的决定因素，并且已证明丁香菌素A可诱导小麦白粉菌定殖的细胞发生超敏死亡，从而将亲和性相互作用重编程为非亲和性相互作用。丁香菌素A是一种三肽的特殊衍生物，其含有一个由5-甲基-4-氨基-2-己烯酸和3,4-脱氢赖氨酸这两种非蛋白质氨基酸组成的12元环。在此，我们报道了参与丁香菌素A生物合成的基因的克隆、测序及分析。这些基因编码的蛋白质包含非核糖体肽合成酶和I型聚酮化合物合成酶典型的模块，以及可能参与丁香菌素A生物合成转录调控和丁香菌素A输出的蛋白质。这些模块的结构和排列导致形成了一个解释三肽合成的模型，包括丁香菌素A环结构中两种非蛋白质氨基酸的形成。
