Project description:Complex in vivo RNA-seq analysis reveal reprogramming of Yersinia from virulent to persistent mode during infection [microarray II]
Project description:Expression of the virulence regulator RovA of Yersinia pseudotuberculosis, is controlled by the ncRNAs CsrB and CsrC through CsrA and RovM. In this study, we show that the regulator YmoA of the Hha family of nucleoid-associated proteins controls expression of the counterregulated Csr-type RNAs and the Csr-RovM-RovA signalling cascade through alterations of the CsrC RNA stability. YmoA-mediated stabilization of CsrC depends on CsrA and H-NS, but not on the RNA chaperone Hfq and involves a stabilizing stem-loop structure within the 5’-region of CsrC. YmoA influence on CsrC stability is complex as YmoA was found to control numerous factors known to affect RNA structures and stability. In addition, YmoA controls temperature-dependent early and later stage virulence genes in an opposite manner and coregulates their expression with bacterial stress responses and metabolic functions. Following oral infections in a mouse model, we demonstrate that a ymoA mutant is strongly reduced in its ability to disseminate to the Peyer’s patches, mesenteric lymph nodes, liver and spleen and exhibits a reduced mortality. We propose a model in which YmoA controls switching from a RovA-dependent early colonization phase towards a virulence plasmid (pYV)-dependent infection phase important for host defense and persistence.
Project description:Expression of the virulence regulator RovA of Yersinia pseudotuberculosis, is controlled by the ncRNAs CsrB and CsrC through CsrA and RovM. In this study, we show that the regulator YmoA of the Hha family of nucleoid-associated proteins controls expression of the counterregulated Csr-type RNAs and the Csr-RovM-RovA signalling cascade through alterations of the CsrC RNA stability. YmoA-mediated stabilization of CsrC depends on CsrA and H-NS, but not on the RNA chaperone Hfq and involves a stabilizing stem-loop structure within the 5M-bM-^@M-^Y-region of CsrC. YmoA influence on CsrC stability is complex as YmoA was found to control numerous factors known to affect RNA structures and stability. In addition, YmoA controls temperature-dependent early and later stage virulence genes in an opposite manner and coregulates their expression with bacterial stress responses and metabolic functions. Following oral infections in a mouse model, we demonstrate that a ymoA mutant is strongly reduced in its ability to disseminate to the PeyerM-bM-^@M-^Ys patches, mesenteric lymph nodes, liver and spleen and exhibits a reduced mortality. We propose a model in which YmoA controls switching from a RovA-dependent early colonization phase towards a virulence plasmid (pYV)-dependent infection phase important for host defense and persistence. For each microarray, 300ng of each Cy3- and Cy5-labelled RNA were mixed, fragmented and hybridized to the microarray at 65M-BM-0C for 17 hours using the Agilent Hybridization Chamber according to the Agilent instructions. Four replicates were performed. Sequences used for the design of the microarray (Agilent, 8 x 15K format) include three different 60-nt oligonucleotides for all 4172 chromosomal genes (ORFs > 30 codons) of the Y. pseudotuberculosis YPIII genome and six probes for the 92 genes of the virulence plasmid pYV of Y. pseudotuberculosis strain IP32953.
Project description:We previously suggested that increased expression of the gene encoding transcriptional antiterminator RfaH during Yersinia pseudotuberculosis transcriptional reprogramming is necessary for adapting to persistent infection. In this study, we examined the role of RfaH in virulence and bacterial physiology under infection-relevant stress conditions, and identified genes differentially regulated in the absence of RfaH in Y. pseudotuberculosis. We employed a mouse infection model and phenotypic assays to test RfaH's role in virulence and physiology, as well as RNA sequencing, including O-antigen biosynthesis-deficient strains. Our findings demonstrate that loss of RfaH significantly attenuates virulence, reducing the capacity of Y. pseudotuberculosis to establish persistent infection. RfaH expression is increased during the stationary growth phase and under various stress conditions, such as high osmolarity and bile salts, which are known to induce envelope stress. Functional assays revealed that the ΔrfaH strain displayed defects in motility and increased clumping, indicating altered surface properties affecting motility. Moreover, transcriptomic profiling of the ΔrfaH strain revealed a specific RfaH-dependent gene set after filtering out genes affected by O-antigen-related mutations, thereby minimizing confounding effects from surface structure alterations. These results suggest that RfaH influences a broader set of virulence and adaptation pathways beyond O-antigen regulation. Collectively, our findings suggest that RfaH is essential for the virulence and adaptive capacity of Y. pseudotuberculosis to colonize the host. This study provides insights into regulatory mechanisms that facilitate bacterial survival in hostile environments and highlights the importance of RfaH and its regulatory targets in the pathogenesis of Y. pseudotuberculosis.