Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.
mSphere. 2020 Mar 18;5(2):e00119-20. doi: 10.1128/mSphere.00119-20.
The hierarchical quorum sensing (QS) systems of , consisting of , , and , coordinate the expression of bacterial virulence genes. Previous studies showed that under phosphate deficiency conditions, two-component regulatory system PhoRB could activate various genes involved in cytotoxicity through modulation of QS systems, but the mechanism by which PhoR/PhoB influences QS remains largely unknown. Here, we provide evidence that among the key QS regulatory genes in , , , , and were activated by the response regulator PhoB under phosphate-depleted conditions. We show that PhoB is a strong competitor against LasR and RsaL for binding to the promoter of and induces significant expression of , , and However, expression of , encoding the signal 3-oxo-C12-HSL, was increased only marginally under the same phosphate-depleted conditions. This seeming inconsistency was attributed to the induction of , which encodes an enzyme for degradation of 3-oxo-C12-HSL signal molecules. Taken together, the results from this study demonstrate that through the two-component regulatory system PhoR/PhoB, phosphate depletion stress could influence the QS network by modulating several key regulators, including , , , and The findings highlight not only the potency of the PhoR/PhoB-mediated bacterial stress response mechanism but also the plasticity of the QS systems in coping with the changed environmental conditions. It is not fully understood how phosphate deficiency could influence the virulence of through modulation of the bacterial QS systems. This report presents a systemic investigation on the impact of phosphate depletion on the hierarchy of quorum sensing systems of The results showed that phosphate stress could have an extensive impact on the QS networks of this bacterial pathogen. Among the 7 QS regulatory genes representing the 3 sets of QS systems tested, 4 were significantly upregulated by phosphate depletion stress through the PhoR/PhoB two-component regulatory system, especially the upstream QS regulatory gene We also present evidence that the response regulator PhoB was a strong competitor against the regulators LasR and RsaL for the promoter, unveiling the mechanistic basis of the process by which phosphate stress could modulate the bacterial QS systems.
该层级式群体感应（QS）系统由、、和组成，协调细菌毒力基因的表达。先前的研究表明，在磷酸盐缺乏的条件下，双组分调控系统 PhoRB 可以通过调控 QS 系统激活各种参与细胞毒性的基因，但 PhoR/PhoB 影响 QS 的机制在很大程度上仍然未知。在这里，我们提供的证据表明，在磷酸盐耗尽条件下，PhoRB 可以激活中的关键 QS 调控基因中的、、、和。我们表明，PhoB 是 LasR 和 RsaL 与 启动子结合的强有力竞争者，并诱导显著表达、和。然而，在相同的磷酸盐耗尽条件下，编码信号 3-oxo-C12-HSL 的基因的表达仅略有增加。这种看似不一致的情况归因于诱导的表达，该基因编码 3-oxo-C12-HSL 信号分子的降解酶。总的来说，这项研究的结果表明，通过双组分调控系统 PhoR/PhoB，磷酸盐耗竭应激可以通过调节包括、、、和等几个关键调控因子来影响 QS 网络。研究结果不仅突出了 PhoR/PhoB 介导的细菌应激反应机制的强大，而且还强调了 QS 系统在应对变化的环境条件时的可塑性。目前还不完全清楚磷酸盐缺乏如何通过调节细菌 QS 系统来影响 的毒力。本报告对磷酸盐缺乏对 QS 系统层次结构的影响进行了系统研究。结果表明，磷酸盐胁迫通过 PhoR/PhoB 双组分调控系统对该细菌病原体的 QS 网络可能产生广泛影响。在所测试的 3 组 QS 系统的 7 个 QS 调控基因中，有 4 个通过磷酸盐胁迫显著上调，特别是上游 QS 调控基因。我们还提供了证据表明，响应调节剂 PhoB 是 LasR 和 RsaL 竞争 启动子的强有力竞争者，揭示了磷酸盐胁迫调节细菌 QS 系统的过程的机制基础。
