Major exopolysaccharide, EPS I, is associated with the feedback loop in the quorum sensing of Ralstonia solanacearum strain OE1-1
Major exopolysaccharide, EPS I, is associated with the feedback loop in the quorum sensing of Ralstonia solanacearum strain OE1-1
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DOI：
10.1111/mpp.12870
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发表时间：
2019-09-27
影响因子：
4.9
通讯作者：
Hikichi, Yasufumi
中科院分区：
文献类型：
--
作者：
Hayashi, Kazusa;Senuma, Wakana;Hikichi, Yasufumi
革兰氏阴性土传细菌青枯雷尔斯顿菌首先感染寄主植物的根部，然后侵入木质部导管。在木质部导管中，细菌旺盛生长并产生胞外多糖（EPS），导致寄主植物出现枯萎症状。因此，EPS 是青枯菌的主要毒力因子。青枯菌的菌株 OE1-1 产生 3-羟基肉豆蔻酸甲酯作为群体感应 (QS) 信号，并感应该 QS 信号，激活 QS。 QS 激活的 LysR 型转录调节因子 PhcA 诱导毒力相关代谢物的产生，包括拉呋喃酮和主要 EPS，EPS I。为了阐明 EPS I 的功能，使用 RNA 测序技术分析了青枯菌菌株的转录组。在 epsB 缺失突变体 Delta epsB 中，97.2% 的 QS 正向调节基因的表达下调，从而丧失了 EPS I 生产力。此外，98.0% 的 QS 负调控基因的表达在 Delta epsB 中上调。 EPS I 缺乏会导致拉呋喃酮生产力显着下降，游动能力显着增强，这会被 QS 抑制，但不会影响 phcA 和 phcB 的表达水平，phcA 和 phcB 编码 3-羟基肉豆蔻酸甲酯生产所需的甲基转移酶。总体而言，QS 依赖性产生的 EPS I 可能与 QS 的反馈回路相关。
The Gram-negative soil-borne bacterium Ralstonia solanacearum first infects roots of host plants and then invades xylem vessels. In xylem vessels, the bacteria grow vigorously and produce exopolysaccharides (EPSs) to cause a wilt symptom on host plants. The EPSs are thus the main virulence factors of R. solanacearum. The strain OE1-1 of R. solanacearum produces methyl 3-hydroxymyristate as a quorum-sensing (QS) signal, and senses this QS signal, activating QS. The QS-activated LysR-type transcriptional regulator PhcA induces the production of virulence-related metabolites including ralfuranone and the major EPS, EPS I. To elucidate the function of EPS I, the transcriptomes of R. solanacearum strains were analysed using RNA sequencing technology. The expression of 97.2% of the positively QS-regulated genes was down-regulated in the epsB-deleted mutant Delta epsB, which lost its EPS I productivity. Furthermore, expression of 98.0% of the negatively QS-regulated genes was up-regulated in Delta epsB. The deficiency to produce EPS I led to a significantly suppressed ralfuranone productivity and significantly enhanced swimming motility, which are suppressed by QS, but did not affect the expression levels of phcA and phcB, which encode a methyltransferase required for methyl 3-hydroxymyristate production. Overall, QS-dependently produced EPS I may be associated with the feedback loop of QS.