biostudies-literatureAroeti LEuropean Research CouncilIsrael Academy of Sciences and Humanities3834https://www.ebi.ac.uk/biostudies/studies/S-EPMC12019536biostudies-literatureUnknown16(1)The RNA-binding protein CsrA regulates the expression of hundreds of genes in several bacterial species, thus controlling virulence and other processes. However, the outcome of the CsrA-mRNA interactions is modulated by competing small RNAs and other factors through mechanisms that are only partially understood. Here, we show that CsrA accumulates in a dynamic membraneless compartment in cells of E. coli and other pathogenic species. In addition to CsrA, the compartment contains components of the RNA-degrading complex (degradosome), regulatory small RNAs, and selected mRNAs. Formation of the compartment is associated with a switch between promoting and repressing virulence gene expression by CsrA. We suggest that similar CsrA switches may be widespread in diverse bacteria.Nature communicationsFormation of a membraneless compartment regulates bacterial virulence.PMC12019536810186833598743/18Argaman LRavins MMargalit HYakovian OAltuvia YFaigenbaum-Romm RKatsowich NBen-Yehuda SAroeti LRosenshine IBejerano-Sagie MElbaz NfalseFormation of a membraneless compartment regulates bacterial virulence.The RNA-binding protein CsrA regulates the expression of hundreds of genes in several bacterial species, thus controlling virulence and other processes. However, the outcome of the CsrA-mRNA interactions is modulated by competing small RNAs and other factors through mechanisms that are only partially understood. Here, we show that CsrA accumulates in a dynamic membraneless compartment in cells of E. coli and other pathogenic species. In addition to CsrA, the compartment contains components of the RNA-degrading complex (degradosome), regulatory small RNAs, and selected mRNAs. Formation of the compartment is associated with a switch between promoting and repressing virulence gene expression by CsrA. We suggest that similar CsrA switches may be widespread in diverse bacteria.2025-01-01T00:00:00Z2025 Apr2026-06-02T10:14:50.258Z2025-07-11T03:05:55.053ZS-EPMC120195364026893510.1038/s41467-025-58829-9