State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China.
Appl Environ Microbiol. 2019 Jul 1;85(14). doi: 10.1128/AEM.00234-19. Print 2019 Jul 15.
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 Our previous investigation indicated that the transcript level of the gene significantly decreased in an RpoE mutant. Here, we found that 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. 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 The alternative sigma factor RpoE is essential for the virulence of 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 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 These findings illuminated the RpoE-RpoX-centered regulatory cascades and their distinct and overlapping regulatory roles in , 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.
是海洋环境中最丰富的微生物之一，也是一种机会性病原体，介导海洋动物中高死亡率的弧菌病。替代σ因子在细菌病原体中在感染过程中适应环境变化和适应各种生态位方面发挥着重要作用，但对它们的了解甚少。我们之前的研究表明，基因的转录水平在 RpoE 突变体中显著降低。在这里，我们发现对高温和低渗透压胁迫有高表达，并受替代σ因子 RpoE 和其自身产物 RpoX 的直接控制。此外，转录组测序 (RNA-seq) 结果表明，RpoE 和 RpoX 具有不同的调控基因，尽管它们在高温 (42°C) 时共同调控 105 个基因，包括与生物膜形成、运动性、毒力、调节因子和应激反应相关的基因。RNA-seq 和染色质免疫沉淀测序 (ChIP-seq) 分析以及电泳迁移率变动分析 (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。RpoX 的缺失似乎不会削弱正常温度下对模式鱼类的毒力。总的来说，这项研究的数据表明，RpoE 和替代σ因子 RpoX 对热和渗透压应激的反应中的调节级联及其在海洋细菌中的致病性和应激反应中的独特和重叠作用。替代σ因子 RpoE 是对海洋鱼类、珊瑚和其他动物的毒力所必需的，以响应海面温度升高。在这项研究中，我们描述了另一个替代σ因子 RpoX，它在高温和低渗透压胁迫条件下被诱导。的表达受到 RpoE 和 RpoX 的严格控制。尽管 RpoE 和 RpoX 共同调控 105 个基因，但它们在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 为中心的调节级联及其在 中的独特和重叠的调节作用，这有助于揭示该细菌在各种海洋动物中因温度波动而引起疾病的机制，并制定应对该细菌感染的适当策略。
