Vibrio alginolyticus is an important fish pathogen causing pandemic diseases in marine animals. Small noncoding RNAs (sRNAs) are important posttranscriptional modulators of gene expression and involved in the pathogenesis of bacterial pathogens. Thus far, no cell density-dependent sRNA has been reported in V. alginolyticus. In this study, a cell density-dependent sRNA, Qrr, predicted based on the previous RNA-Seq analysis of V. alginolyticus cultured at low cell density (LCD) and high cell density (HCD), was characterized. The Qrr mutant showed significantly impaired growth and decreased swimming and swarming ability, and increased biofilm formation, extracellular polysaccharide content, serine protease production, and LD50 values during zebrafish infection in contrast to the wild-type strain. Qrr modulates the master regulators LuxR and AphA in quorum sensing (QS) pathways possibly at the posttranscriptional level by base pairing with the 5'-untranslated regions (5'-UTRs). Meanwhile, both LuxR and AphA could directly bind to the promoter of qrr to activate or repress its transcription, respectively. Moreover, our unbiased metabolic approaches revealed that Qrr modulates a large quantity of metabolic and lipidomic pathways, including amino acids, purine and pyrimidine derivatives, tricarboxylic acid cycle (TCA cycle) intermediates, and lipids. Collectively, this work contributes to a systematic understanding of regulatory roles of the cell density-dependent sRNA, Qrr, in V. alginolyticus.

中文翻译：

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细胞密度依赖性sRNA，Qrr的特征及其在溶藻弧菌中群体感应和代谢调控中的作用。

溶藻弧菌是导致海洋动物大流行疾病的重要鱼类病原体。小型非编码RNA（sRNA）是基因表达的重要转录后调节剂，并参与细菌病原体的发病机理。迄今为止，尚未在溶藻弧菌中报道细胞密度依赖性sRNA。在这项研究中，对基于细胞密度的sRNA Qrr（基于先前在低细胞密度（LCD）和高细胞密度（HCD）下培养的溶藻弧菌的RNA-Seq分析进行了预测）进行了表征。与野生型菌株相比，在斑马鱼感染期间，Qrr突变体显示出显着受损的生长并降低了游泳和成群的能力，并增加了生物膜形成，胞外多糖含量，丝氨酸蛋白酶产生和LD50值。Qrr通过与5'-非翻译区（5'-UTR）碱基配对，在转录后水平上调节群体感应（QS）途径中的主调节子LuxR和AphA。同时，LuxR和AphA都可以直接与qrr启动子结合，分别激活或抑制其转录。此外，我们无偏见的代谢方法表明，Qrr可调节大量的代谢和脂质组学途径，包括氨基酸，嘌呤和嘧啶衍生物，三羧酸循环（TCA循环）中间体和脂质。总的来说，这项工作有助于系统地了解溶藻弧菌中依赖细胞密度的sRNA Qrr的调控作用。同时，LuxR和AphA都可以直接与qrr启动子结合，分别激活或抑制其转录。此外，我们无偏见的代谢方法表明，Qrr可调节大量的代谢和脂质组学途径，包括氨基酸，嘌呤和嘧啶衍生物，三羧酸循环（TCA循环）中间体和脂质。总的来说，这项工作有助于系统地了解溶藻弧菌中依赖细胞密度的sRNA Qrr的调控作用。同时，LuxR和AphA都可以直接与qrr启动子结合，分别激活或抑制其转录。此外，我们无偏见的代谢方法表明，Qrr可调节大量的代谢和脂质组学途径，包括氨基酸，嘌呤和嘧啶衍生物，三羧酸循环（TCA循环）中间体和脂质。总的来说，这项工作有助于系统地了解溶藻弧菌中依赖细胞密度的sRNA Qrr的调控作用。三羧酸循环（TCA循环）的中间体和脂质。总的来说，这项工作有助于系统地了解溶藻弧菌中依赖细胞密度的sRNA Qrr的调控作用。三羧酸循环（TCA循环）的中间体和脂质。总的来说，这项工作有助于系统地了解溶藻弧菌中依赖细胞密度的sRNA Qrr的调控作用。