Small RNAs, Large Networks: Posttranscriptional Regulons in Gram-Negative Bacteria

• Published in: Annual review of microbiology Vol. 77; no. 1; pp. 23 - 43
• Main Authors: Papenfort, Kai, Melamed, Sahar
• Format: Journal Article
• Language: English
• Published: United States Annual Reviews 15-09-2023; Annual Reviews, Inc
• Subjects: Bacteria; Gene expression; gene networks; Gram-negative bacteria; Hfq; Networks; Post-transcription; regulatory motifs; Ribonucleic acid; RNA; RNA-binding protein; small RNA; sponge RNA; Transcription factors
• ISSN: 0066-4227; 1545-3251; 1545-3251
• DOI: 10.1146/annurev-micro-041320-025836

Small regulatory RNA (sRNAs) are key mediators of posttranscriptional gene control in bacteria. Assisted by RNA-binding proteins, a single sRNA often modulates the expression of dozens of genes, and thus sRNAs frequently adopt central roles in regulatory networks. Posttranscriptional regulation by sRNAs comes with several unique features that cannot be achieved by transcriptional regulators. However, for optimal network performance, transcriptional and posttranscriptional control mechanisms typically go hand-in-hand. This view is reflected by the ever-growing class of mixed network motifs involving sRNAs and transcription factors, which are ubiquitous in biology and whose regulatory properties we are beginning to understand. In addition, sRNA activity can be antagonized by base-pairing with sponge RNAs, adding yet another layer of complexity to these networks. In this article, we summarize the regulatory concepts underlying sRNA-mediated gene control in bacteria and discuss how sRNAs shape the output of a network, focusing on several key examples.