Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA.
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
mSphere. 2018 Oct 24;3(5):e00423-18. doi: 10.1128/mSphere.00423-18.
The intracellular signaling molecule cyclic diguanylate (c-di-GMP) regulates many processes in bacteria, with a central role in controlling the switch between motile and nonmotile lifestyles. Recent work has shown that in (also called ), c-di-GMP regulates swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we determined the transcriptional regulon of c-di-GMP in employing overexpression of a diguanylate cyclase gene to artificially manipulate intracellular c-di-GMP. Consistent with prior work, c-di-GMP regulated the expression of genes involved in swimming and surface motility. c-di-GMP also affected the expression of multiple genes encoding cell envelope proteins, several of which affected biofilm formation A substantial proportion of the c-di-GMP regulon appears to be controlled either directly or indirectly via riboswitches. We confirmed the functionality of 11 c-di-GMP riboswitches, demonstrating their effects on downstream gene expression independent of the upstream promoters. The class I riboswitches uniformly functioned as "off" switches in response to c-di-GMP, while class II riboswitches acted as "on" switches. Transcriptional analyses of genes 3' of c-di-GMP riboswitches over a broad range of c-di-GMP levels showed that relatively modest changes in c-di-GMP levels are capable of altering gene transcription, with concomitant effects on microbial behavior. This work expands the known c-di-GMP signaling network in and emphasizes the role of the riboswitches in controlling known and putative virulence factors in In , the signaling molecule c-di-GMP regulates multiple processes affecting its ability to cause disease, including swimming and surface motility, biofilm formation, toxin production, and intestinal colonization. In this study, we used RNA-seq to define the transcriptional regulon of c-di-GMP in Many new targets of c-di-GMP regulation were identified, including multiple putative colonization factors. Transcriptional analyses revealed a prominent role for riboswitches in c-di-GMP signaling. Only a subset of the 16 previously predicted c-di-GMP riboswitches were functional and displayed potential variability in their response kinetics to c-di-GMP. This work underscores the importance of studying c-di-GMP riboswitches in a relevant biological context and highlights the role of the riboswitches in controlling gene expression in .
细胞内信号分子环二鸟苷酸（c-di-GMP）调节细菌中的许多过程，在控制运动和非运动生活方式之间的转换中起核心作用。最近的工作表明，在 （也称为）中，c-di-GMP 调节游泳和表面运动、生物膜形成、毒素产生和肠道定植。在这项研究中，我们通过过表达二鸟苷酸环化酶基因来人为操纵细胞内 c-di-GMP，从而确定 c-di-GMP 在 中的转录调控物。与先前的工作一致，c-di-GMP 调节参与游泳和表面运动的基因的表达。c-di-GMP 还影响编码细胞包膜蛋白的多个基因的表达，其中几个基因影响生物膜形成。c-di-GMP 调控物的很大一部分似乎直接或间接通过核糖体开关控制。我们证实了 11 个 c-di-GMP 核糖体开关的功能，证明了它们对下游基因表达的影响独立于上游启动子。类 I 核糖体开关在响应 c-di-GMP 时均作为“关闭”开关起作用，而类 II 核糖体开关作为“开启”开关起作用。在广泛的 c-di-GMP 水平范围内对 c-di-GMP 核糖体开关 3' 处的基因进行转录分析表明，c-di-GMP 水平的相对较小变化能够改变基因转录，并对微生物行为产生相应影响。这项工作扩展了 中已知的 c-di-GMP 信号网络，并强调了核糖体开关在控制 中已知和潜在的毒力因子中的作用。在 中，信号分子 c-di-GMP 调节多个影响其致病能力的过程，包括游泳和表面运动、生物膜形成、毒素产生和肠道定植。在这项研究中，我们使用 RNA-seq 来定义 c-di-GMP 在 中的转录调控物。确定了多个 c-di-GMP 调节的新靶点，包括多个假定的定植因子。转录分析揭示了核糖体开关在 c-di-GMP 信号中的重要作用。只有先前预测的 16 个 c-di-GMP 核糖体开关中的一部分具有功能，并且对 c-di-GMP 的响应动力学表现出潜在的可变性。这项工作强调了在相关生物学背景下研究 c-di-GMP 核糖体开关的重要性，并突出了核糖体开关在控制 中基因表达的作用。
