TY - JOUR A1 - Svensson, Sarah L. A1 - Sharma, Cynthia M. T1 - Small RNAs that target G-rich sequences are generated by diverse biogenesis pathways in Epsilonproteobacteria JF - Molecular Microbiology N2 - Bacterial small RNAs (sRNAs) are widespread post-transcriptional regulators that control bacterial stress responses and virulence. Nevertheless, little is known about how they arise and evolve. Homologs can be difficult to identify beyond the strain level using sequence-based approaches, and similar functionalities can arise by convergent evolution. Here, we found that the virulence-associated CJnc190 sRNA of the foodborne pathogen Campylobacter jejuni resembles the RepG sRNA from the gastric pathogen Helicobacter pylori. However, while both sRNAs bind G-rich sites in their target mRNAs using a C/U-rich loop, they largely differ in their biogenesis. RepG is transcribed from a stand-alone gene and does not require processing, whereas CJnc190 is transcribed from two promoters as precursors that are processed by RNase III and also has a cis-encoded antagonist, CJnc180. By comparing CJnc190 homologs in diverse Campylobacter species, we show that RNase III-dependent processing of CJnc190 appears to be a conserved feature even outside of C. jejuni. We also demonstrate the CJnc180 antisense partner is expressed in C. coli, yet here might be derived from the 3’UTR (untranslated region) of an upstream flagella-related gene. Our analysis of G-tract targeting sRNAs in Epsilonproteobacteria demonstrates that similar sRNAs can have markedly different biogenesis pathways. KW - sRNA biogenesis KW - Campylobacter jejuni KW - Helicobacter pylori KW - pathogenesis KW - RNase III Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259602 VL - 117 ER - TY - JOUR A1 - Dugar, Gaurav A1 - Svensson, Sarah L. A1 - Bischler, Thorsten A1 - Waldchen, Sina A1 - Reinhardt, Richard A1 - Sauer, Markus A1 - Sharma, Cynthia M. T1 - The CsrA-FliW network controls polar localization of the dual-function flagellin mRNA in Campylobacter jejuni JF - Nature Communications N2 - The widespread CsrA/RsmA protein regulators repress translation by binding GGA motifs in bacterial mRNAs. CsrA activity is primarily controlled through sequestration by multiple small regulatory RNAs. Here we investigate CsrA activity control in the absence of antagonizing small RNAs by examining the CsrA regulon in the human pathogen Campylobacter jejuni. We use genome-wide co-immunoprecipitation combined with RNA sequencing to show that CsrA primarily binds flagellar mRNAs and identify the major flagellin mRNA (flaA) as the main CsrA target. The flaA mRNA is translationally repressed by CsrA, but it can also titrate CsrA activity. Together with the main C. jejuni CsrA antagonist, the FliW protein, flaA mRNA controls CsrA-mediated post-transcriptional regulation of other flagellar genes. RNA-FISH reveals that flaA mRNA is expressed and localized at the poles of elongating cells. Polar flaA mRNA localization is translation dependent and is post-transcriptionally regulated by the CsrA-FliW network. Overall, our results suggest a role for CsrA-FliW in spatiotemporal control of flagella assembly and localization of a dual-function mRNA. KW - bacterial genetics KW - cell signalling KW - translation KW - Campylobacter jejuni Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173201 VL - 7 ER - TY - JOUR A1 - Alzheimer, Mona A1 - Svensson, Sarah L. A1 - König, Fabian A1 - Schweinlin, Matthias A1 - Metzger, Marco A1 - Walles, Heike A1 - Sharma, Cynthia M. T1 - A three-dimensional intestinal tissue model reveals factors and small regulatory RNAs important for colonization with Campylobacter jejuni JF - PLoS Pathogens N2 - The Gram-negative Epsilonproteobacterium Campylobacter jejuni is currently the most prevalent bacterial foodborne pathogen. Like for many other human pathogens, infection studies with C. jejuni mainly employ artificial animal or cell culture models that can be limited in their ability to reflect the in-vivo environment within the human host. Here, we report the development and application of a human three-dimensional (3D) infection model based on tissue engineering to study host-pathogen interactions. Our intestinal 3D tissue model is built on a decellularized extracellular matrix scaffold, which is reseeded with human Caco-2 cells. Dynamic culture conditions enable the formation of a polarized mucosal epithelial barrier reminiscent of the 3D microarchitecture of the human small intestine. Infection with C. jejuni demonstrates that the 3D tissue model can reveal isolate-dependent colonization and barrier disruption phenotypes accompanied by perturbed localization of cell-cell junctions. Pathogenesis-related phenotypes of C. jejuni mutant strains in the 3D model deviated from those obtained with 2D-monolayers, but recapitulated phenotypes previously observed in animal models. Moreover, we demonstrate the involvement of a small regulatory RNA pair, CJnc180/190, during infections and observe different phenotypes of CJnc180/190 mutant strains in 2D vs. 3D infection models. Hereby, the CJnc190 sRNA exerts its pathogenic influence, at least in part, via repression of PtmG, which is involved in flagellin modification. Our results suggest that the Caco-2 cell-based 3D tissue model is a valuable and biologically relevant tool between in-vitro and in-vivo infection models to study virulence of C. jejuni and other gastrointestinal pathogens. KW - in vitro KW - stem cells KW - invasion KW - host KW - adhesion KW - epithelial cells KW - translocation KW - virulence KW - responses KW - microenvironment Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229454 VL - 16 IS - 2 ER -