A Homologue of the 3-Oxoacyl-(Acyl Carrier Protein) Synthase III Gene Located in the Glycosylation Island of Pseudomonas syringae pv. tabaci Regulates Virulence Factors via N-Acyl Homoserine Lactone and Fatty Acid Synthesis
A Homologue of the 3-Oxoacyl-(Acyl Carrier Protein) Synthase III Gene Located in the Glycosylation Island of Pseudomonas syringae pv. tabaci Regulates Virulence Factors via N-Acyl Homoserine Lactone and Fatty Acid Synthesis
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DOI：
10.1128/jb.00763-06
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发表时间：
2006-10
影响因子：
3.2
通讯作者：
F. Taguchi;Yujiro Ogawa;K. Takeuchi;Tomoko Suzuki;K. Toyoda;T. Shiraishi;Y. Ichinose
中科院分区：
文献类型：
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作者：
F. Taguchi;Yujiro Ogawa;K. Takeuchi;Tomoko Suzuki;K. Toyoda;T. Shiraishi;Y. Ichinose
丁香假单胞菌；烟草6605具有一个参与鞭毛蛋白糖基化的遗传区域。该区域由orf1、orf2和orf3三个开放读帧组成。我们之前的研究表明orf1和orf2编码糖基转移酶；另一方面，orf3在鞭毛蛋白的翻译后修饰中没有作用。虽然Orf3的功能尚不清楚，但Orf3缺失突变体（Δorf3突变体）降低了对烟草的毒力。Orf3在脂肪酸延伸循环中与3-氧酰-（酰基载体蛋白）合成酶III具有显著的同源性。Δorf3突变体形成酰基高丝氨酸内酯（AHL）的能力显著降低，AHL是群体感应分子，这表明Orf3是AHL合成所必需的。与野生型菌株相比，Δorf3突变体的蜂群能动性、生物表面活性剂的产生以及对H2O2和抗生素的耐受性都有所增强。接种菌在烟叶表面的扫描电镜显示，Δorf3突变体细胞周围几乎没有细胞外聚合物基质。Δorf3突变体和AHL合成（ΔpsyI）突变体的表型相似，尽管Δorf3突变体的突变特异性特征更为极端。Δorf3突变体的群体能动性大于ΔpsyI突变体。这归因于Δorf3突变体中过量产生生物表面活性剂和/或替代脂肪酸代谢的协同作用。此外，铁和生物表面活性剂的数量似乎参与了丁香花中群体感应调节的生物膜发育。6605年烟。
ABSTRACT Pseudomonas syringae pv. tabaci 6605 possesses a genetic region involved in flagellin glycosylation. This region is composed of three open reading frames: orf1, orf2, and orf3. Our previous study revealed that orf1 and orf2 encode glycosyltransferases; on the other hand, orf3 has no role in posttranslational modification of flagellin. Although the function of Orf3 remained unclear, an orf3 deletion mutant (Δorf3 mutant) had reduced virulence on tobacco plants. Orf3 shows significant homology to a 3-oxoacyl-(acyl carrier protein) synthase III in the fatty acid elongation cycle. The Δorf3 mutant had a significantly reduced ability to form acyl homoserine lactones (AHLs), which are quorum-sensing molecules, suggesting that Orf3 is required for AHL synthesis. In comparison with the wild-type strain, swarming motility, biosurfactant production, and tolerance to H2O2 and antibiotics were enhanced in the Δorf3 mutant. A scanning electron micrograph of inoculated bacteria on the tobacco leaf surface revealed that there is little extracellular polymeric substance matrix surrounding the cells in the Δorf3 mutant. The phenotypes of the Δorf3 mutant and an AHL synthesis (ΔpsyI) mutant were similar, although the mutant-specific characteristics were more extreme in the Δorf3 mutant. The swarming motility of the Δorf3 mutant was greater than that of the ΔpsyI mutant. This was attributed to the synergistic effects of the overproduction of biosurfactants and/or alternative fatty acid metabolism in the Δorf3 mutant. Furthermore, the amounts of iron and biosurfactant seem to be involved in biofilm development under quorum-sensing regulation in P. syringae pv. tabaci 6605.