PsyR, a transcriptional regulator in quorum sensing system, binds lux box-like sequence in psyI promoter without AHL quorum sensing molecule and activates psyI transcription with AHL in Pseudomonas syringae pv. tabaci 6605
PsyR, a transcriptional regulator in quorum sensing system, binds lux box-like sequence in psyI promoter without AHL quorum sensing molecule and activates psyI transcription with AHL in Pseudomonas syringae pv. tabaci 6605
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DOI：
10.1007/s10327-019-00893-3
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发表时间：
2019-11-11
影响因子：
1.2
通讯作者：
Matsui, Hidenori
中科院分区：
文献类型：
--
作者：
Ichinose, Yuki;Tasaka, Yousuke;Matsui, Hidenori
群体感应（Quorum sensing，QS）是细菌利用QS信号进行细胞间通讯的一种机制。N-酰基高丝氨酸内酯（AHLs），QS信号在假单胞菌pv. tabaci（Pta）6605由阿勒合酶（PsyI）合成并由同源转录因子PsyR识别。为了揭示PsyR在致病性中的作用，我们产生了一个psyR突变体，并补充了Pta 6605菌株，发现psyR突变体在阿勒产生和致病能力以及在寄主烟草叶片中的繁殖能力显着降低。补充菌株的表型恢复到野生型（WT）的表型。由于psyR突变体几乎失去了所有的阿勒生产，我们研究了PsyR在psyI转录和阿勒生产中的功能。电泳迁移率变动分析表明，重组PsyR蛋白结合psyI的启动子区，但没有阿勒的psyR。添加阿勒并不显著影响这种结合。该区域的结合核心序列被鉴定为20-bp的lux盒样序列。为了揭示PsyR和阿勒在psyI转录中的功能，我们构建了psyI启动子：：lacZYA嵌合报告基因，并将其插入Pta 6605的WT和psyI突变体中。β-半乳糖苷酶活性在WT中以细菌密度依赖性方式增加，并且在加入外源性阿勒后的psyI突变体中也是如此。这些结果表明，单独的PsyR结合psyI启动子中的lux盒，并在阿勒的伴随存在下激活转录。
Quorum sensing (QS) is a mechanism for bacterial cell-cell communication using QS signals. N-acyl-homoserine lactones (AHLs), QS signals in Pseudomonas syringae pv. tabaci (Pta) 6605, are synthesized by an AHL synthase (PsyI) and recognized by the cognate transcription factor PsyR. To reveal the role of PsyR in virulence, we generated a psyR mutant and complemented strains of Pta 6605 and found that the psyR mutant is remarkably reduced in AHL production and ability to cause disease and propagate in host tobacco leaves. The phenotypes of complemented strains were restored to that of the wild type (WT). Because the psyR mutant lost nearly all AHL production, we investigated the function of PsyR in the transcription of psyI and production of AHL. Electrophoretic mobility shift assays suggested that the recombinant PsyR protein binds the promoter region of psyI but not psyR without AHL. The addition of AHL did not significantly affect this binding. The binding core sequence of this region was identified as a 20-bp lux box-like sequence. To reveal the function of PsyR and AHL on psyI transcription, we constructed a psyI promoter::lacZYA chimeric reporter gene, and inserted it into the WT and psyI mutant of Pta 6605. beta-galactosidase activity increased in a bacterial density-dependent manner in the WT and also in a psyI mutant after the addition of exogenous AHL. These results indicate that the solo PsyR binds the lux box in the psyI promoter and activates transcription in the concomitant presence of AHL.