Alternative Sigma Factor RpoX Is a Part of the RpoE Regulon and Plays Distinct Roles in Stress Responses, Motility, Biofilm Formation, and Hemolytic Activities in the Marine Pathogen Vibrio alginolyticus
Alternative Sigma Factor RpoX Is a Part of the RpoE Regulon and Plays Distinct Roles in Stress Responses, Motility, Biofilm Formation, and Hemolytic Activities in the Marine Pathogen Vibrio alginolyticus
复制标题
替代 Sigma 因子 RpoX 是 RpoE 调节子的一部分，在海洋病原体溶藻弧菌的应激反应、运动、生物膜形成和溶血活动中发挥独特作用
DOI：
10.1128/aem.00234-19
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发表时间：
2019-07-01
影响因子：
4.4
通讯作者：
Wang, Qiyao
中科院分区：
文献类型：
--
作者：
Gu, Dan;Zhang, Jun;Wang, Qiyao
备选西格玛因子RpoE对于溶藻弧菌对海洋鱼类、珊瑚和其他动物的毒力是至关重要的，以响应海面温度的升高。在这项研究中，我们表征了另一种可替代的sigma因子RpoX，它是在高温和低渗透胁迫条件下诱导的。rpoX的表达受RpoE和rpoX的严格控制。虽然RpoE和RpoX共调控105个基因，但它们在溶藻弧菌的应激反应和毒力中具有不同的调控功能。这些发现阐明了以rpoe - rpox为中心的调控级联及其在溶藻弧菌中独特和重叠的调控作用，有助于揭示细菌在各种海洋动物中引起疾病的机制，以响应温度波动，并制定适当的策略来应对这种细菌的感染。摘要溶藻弧菌是海洋环境中最丰富的微生物之一，也是一种介导海洋动物高死亡率弧菌病的条件致病菌。其他sigma因子在细菌病原菌感染过程中对环境变化的适应和对各种生态位的适应中发挥着重要作用，但对溶藻弧菌的了解甚少。我们之前的研究表明，rpoX基因的转录水平在RpoE突变体中显著降低。本研究发现，rpoX在高温低渗透胁迫下高表达，并受替代sigma因子RpoE及其自身产物rpoX的直接控制。此外，转录组测序（RNA-seq）结果显示，尽管RpoE和RpoX在高温（42°C）下共同调控105个基因，包括与生物膜形成、运动性、毒力、调控因子和应激反应相关的基因，但它们具有不同的调控机制。RNA-seq和染色质免疫沉淀测序（ChIP-seq）分析以及电泳迁移迁移分析（emsa）揭示了RpoE和RpoX蛋白的不同结合基序。此外，定量实时逆转录pcr （qRT-PCR）分析也证实，RpoX可以在较高温度下上调与鞭毛、生物膜形成和溶血活性相关的基因。在正常温度下，废除rpoX似乎不会减弱对模型鱼的毒力。总的来说，本研究的数据证明了RpoE和另一个sigma因子RpoX在海洋细菌V. alginolyticus中对热胁迫和渗透胁迫的调控级联反应，以及它们在发病和胁迫反应中的独特和重叠作用。重要意义替代sigma因子RpoE对于溶藻弧菌对海洋鱼类、珊瑚和其他动物的毒力是至关重要的，以响应海面温度的升高。在这项研究中，我们表征了另一种可替代的sigma因子RpoX，它是在高温和低渗透胁迫条件下诱导的。rpoX的表达受RpoE和rpoX的严格控制。虽然RpoE和RpoX共调控105个基因，但它们在溶藻弧菌的应激反应和毒力中具有不同的调控功能。这些发现阐明了以rpoe - rpox为中心的调控级联及其在溶藻弧菌中独特和重叠的调控作用，有助于揭示细菌在各种海洋动物中引起疾病的机制，以响应温度波动，并制定适当的策略来应对这种细菌的感染。
The alternative sigma factor RpoE is essential for the virulence of Vibrio alginolyticus toward marine fish, coral, and other animals in response to sea surface temperature increases. In this study, we characterized another alternative sigma factor, RpoX, which is induced at high temperatures and under low-osmotic-stress conditions. The expression of rpoX is under the tight control of RpoE and RpoX. Although RpoE and RpoX coregulate 105 genes, they are programming different regulatory functions in stress responses and virulence in V. alginolyticus. These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in V. alginolyticus, which facilitates unraveling of the mechanisms by which the bacterium causes diseases in various sea animals in response to temperature fluctuations as well as the development of appropriate strategies to tackle infections by this bacterium. ABSTRACT Vibrio alginolyticus is one of the most abundant microorganisms in marine environments and is also an opportunistic pathogen mediating high-mortality vibriosis in marine animals. Alternative sigma factors play essential roles in bacterial pathogens in the adaptation to environmental changes during infection and the adaptation to various niches, but little is known about them for V. alginolyticus. Our previous investigation indicated that the transcript level of the gene rpoX significantly decreased in an RpoE mutant. Here, we found that rpoX was highly expressed in response to high temperature and low osmotic stress and was under the direct control of the alternative sigma factor RpoE and its own product RpoX. Moreover, transcriptome sequencing (RNA-seq) results showed that RpoE and RpoX had different regulons, although they coregulated 105 genes at high temperature (42°C), including genes associated with biofilm formation, motility, virulence, regulatory factors, and the stress response. RNA-seq and chromatin immunoprecipitation sequencing (ChIP-seq) analyses as well as electrophoretic mobility shift assays (EMSAs) revealed the distinct binding motifs of RpoE and RpoX proteins. Furthermore, quantitative real-time reverse transcription-PCR (qRT-PCR) analysis also confirmed that RpoX can upregulate genes associated with flagella, biofilm formation, and hemolytic activities at higher temperatures. rpoX abrogation does not appear to attenuate virulence toward model fish at normal temperature. Collectively, data from this study demonstrated the regulatory cascades of RpoE and an alternative sigma factor, RpoX, in response to heat and osmotic stresses and their distinct and overlapping roles in pathogenesis and stress responses in the marine bacterium V. alginolyticus. IMPORTANCE The alternative sigma factor RpoE is essential for the virulence of Vibrio alginolyticus toward marine fish, coral, and other animals in response to sea surface temperature increases. In this study, we characterized another alternative sigma factor, RpoX, which is induced at high temperatures and under low-osmotic-stress conditions. The expression of rpoX is under the tight control of RpoE and RpoX. Although RpoE and RpoX coregulate 105 genes, they are programming different regulatory functions in stress responses and virulence in V. alginolyticus. These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in V. alginolyticus, which facilitates unraveling of the mechanisms by which the bacterium causes diseases in various sea animals in response to temperature fluctuations as well as the development of appropriate strategies to tackle infections by this bacterium.