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  • Bacteria
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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 25 August 2015, Vol.112(34), pp.E4772-81
    Description: Horizontal gene transfer via plasmid conjugation is a major driving force in microbial evolution but constitutes a complex process that requires synchronization with the physiological state of the host bacteria. Although several host transcription factors are known to regulate plasmid-borne transfer genes, RNA-based regulatory circuits for host-plasmid communication remain unknown. We describe a posttranscriptional mechanism whereby the Hfq-dependent small RNA, RprA, inhibits transfer of pSLT, the virulence plasmid of Salmonella enterica. RprA employs two separate seed-pairing domains to activate the mRNAs of both the sigma-factor σ(S) and the RicI protein, a previously uncharacterized membrane protein here shown to inhibit conjugation. Transcription of ricI requires σ(S) and, together, RprA and σ(S) orchestrate a coherent feedforward loop with AND-gate logic to tightly control the activation of RicI synthesis. RicI interacts with the conjugation apparatus protein TraV and limits plasmid transfer under membrane-damaging conditions. To our knowledge, this study reports the first small RNA-controlled feedforward loop relying on posttranscriptional activation of two independent targets and an unexpected role of the conserved RprA small RNA in controlling extrachromosomal DNA transfer.
    Keywords: Hfq ; Rpra ; Feedforward Control ; Plasmid Conjugation ; Srna ; Chromosomes, Bacterial ; DNA, Bacterial -- Genetics ; RNA, Bacterial -- Genetics ; Salmonella -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    In: Nature, 2011, Vol.471(7340), p.602
    Description: CRISPR/Cas systems constitute a widespread class of immunity systems that protect bacteria and archaea against phages and plasmids, and commonly use repeat/spacer-derived short crRNAs to silence foreign nucleic acids in a sequence-specific manner. Although the maturation of crRNAs represents a key event in CRISPR activation, the responsible endoribonucleases (CasE, Cas6, Csy4) are missing in many CRISPR/Cas subtypes. Here, differential RNA sequencing of the human pathogen Streptococcus pyogenes uncovered tracrRNA, a trans -encoded small RNA with 24 nucleotide complementarity to the repeat regions of crRNA precursor transcripts. We show that tracrRNA directs the maturation of crRNAs by the activities of the widely conserved endogenous RNase III and the CRISPR-associated Csn1 protein; all these components are essential to protect S. pyogenes against prophage-derived DNA. Our study reveals a novel pathway of small guide RNA maturation and the first example of a host factor (RNase III) required for bacterial RNA-mediated immunity against invaders.
    Keywords: Article;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 3
    In: EMBO Journal, 03 July 2013, Vol.32(13), pp.1802-1804
    Description: CRISPR systems not only defend bacteria from foreign DNA but also contribute to pathogenicity, by regulating endogenous gene expression to evade host innate immune responses.
    Keywords: Animals–Immunology ; Female–Pathogenicity ; Gammaproteobacteria–Immunology ; Gammaproteobacteria–Immunology ; Immune Evasion–Immunology ; Immunity, Innate–Immunology ; Germany ; Prokaryotes ; Gene Expression ; Eukaryotes ; Bacteria ; Molecular Biology;
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 4
    In: Molecular Microbiology, December 2010, Vol.78(6), pp.1327-1331
    Description: Although most bacterial small RNAs act to repress target mRNAs, some also activate messengers. The predominant mode of activation has been seen in ‘anti‐antisense’ regulation whereby a small RNA prevents the formation of an inhibitory 5′ mRNA structure that otherwise impairs translational initiation and protein synthesis. The translational activation might also stabilize the target yet this was considered a secondary effect in the examples known thus far. Two recent papers in investigate post‐transcriptional activation of collagenase mRNA by VR‐RNA, and streptokinase mRNA by FasX RNA, to suggest that small RNAs exert positive regulation of virulence genes primarily at the level of mRNA stabilization.
    Keywords: Protein Synthesis ; Messenger Rna;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 5
    Language: English
    In: PLoS ONE, 2011, Vol.6(3), p.e17296
    Description: P-bodies are dynamic aggregates of RNA and proteins involved in several post-transcriptional regulation processes. P-bodies have been shown to play important roles in regulating viral infection, whereas their interplay with bacterial pathogens, specifically intracellular bacteria that extensively manipulate host cell pathways, remains unknown. Here, we report that Salmonella infection induces P-body disassembly in a cell type-specific manner, and independently of previously characterized pathways such as inhibition of host cell RNA synthesis or microRNA-mediated gene silencing. We show that the Salmonella -induced P-body disassembly depends on the activation of the SPI-2 encoded type 3 secretion system, and that the secreted effector protein SpvB plays a major role in this process. P-body disruption is also induced by the related pathogen, Shigella flexneri , arguing that this might be a new mechanism by which intracellular bacterial pathogens subvert host cell function.
    Keywords: Research Article ; Biology ; Medicine ; Infectious Diseases ; Microbiology ; Molecular Biology ; Cell Biology
    E-ISSN: 1932-6203
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  • 6
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 10 September 2013, Vol.110(37), pp.E3487-96
    Description: Small RNAs (sRNAs) constitute a large and heterogeneous class of bacterial gene expression regulators. Much like eukaryotic microRNAs, these sRNAs typically target multiple mRNAs through short seed pairing, thereby acting as global posttranscriptional regulators. In some bacteria, evidence for hundreds to possibly more than 1,000 different sRNAs has been obtained by transcriptome sequencing. However, the experimental identification of possible targets and, therefore, their confirmation as functional regulators of gene expression has remained laborious. Here, we present a strategy that integrates phylogenetic information to predict sRNA targets at the genomic scale and reconstructs regulatory networks upon functional enrichment and network analysis (CopraRNA, for Comparative Prediction Algorithm for sRNA Targets). Furthermore, CopraRNA precisely predicts the sRNA domains for target recognition and interaction. When applied to several model sRNAs, CopraRNA revealed additional targets and functions for the sRNAs CyaR, FnrS, RybB, RyhB, SgrS, and Spot42. Moreover, the mRNAs gdhA, lrp, marA, nagZ, ptsI, sdhA, and yobF-cspC were suggested as regulatory hubs targeted by up to seven different sRNAs. The verification of many previously undetected targets by CopraRNA, even for extensively investigated sRNAs, demonstrates its advantages and shows that CopraRNA-based analyses can compete with experimental target prediction approaches. A Web interface allows high-confidence target prediction and efficient classification of bacterial sRNAs.
    Keywords: E. Coli ; RNA–RNA Interaction ; Regulatory RNA ; RNA, Bacterial -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 7
    Language: English
    In: Nature, 28 January 2016, Vol.529(7587), pp.496-501
    Description: Bacteria express many small RNAs for which the regulatory roles in pathogenesis have remained poorly understood due to a paucity of robust phenotypes in standard virulence assays. Here we use a generic 'dual RNA-seq' approach to profile RNA expression simultaneously in pathogen and host during Salmonella enterica serovar Typhimurium infection and reveal the molecular impact of bacterial riboregulators. We identify a PhoP-activated small RNA, PinT, which upon bacterial internalization temporally controls the expression of both invasion-associated effectors and virulence genes required for intracellular survival. This riboregulatory activity causes pervasive changes in coding and noncoding transcripts of the host. Interspecies correlation analysis links PinT to host cell JAK-STAT signalling, and we identify infection-specific alterations in multiple long noncoding RNAs. Our study provides a paradigm for a sensitive RNA-based analysis of intracellular bacterial pathogens and their hosts without physical separation, as well as a new discovery route for hidden functions of pathogen genes.
    Keywords: Gene Expression Regulation -- Genetics ; Host-Pathogen Interactions -- Genetics ; RNA, Bacterial -- Genetics ; RNA, Untranslated -- Genetics ; Salmonella Typhimurium -- Genetics
    ISSN: 00280836
    E-ISSN: 1476-4687
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  • 8
    Language: English
    In: Cell, 11 April 2013, Vol.153(2), pp.426-437
    Description: Glucose homeostasis is strictly controlled in all domains of life. Bacteria that are unable to balance intracellular sugar levels and deal with potentially toxic phosphosugars cease growth and risk being outcompeted. Here, we identify the conserved haloacid dehalogenase (HAD)-like enzyme YigL as the previously hypothesized phosphatase for detoxification of phosphosugars and reveal that its synthesis is activated by an Hfq-dependent small RNA in . We show that the glucose-6-P-responsive small RNA SgrS activates YigL synthesis in a translation-independent fashion by the selective stabilization of a decay intermediate of the dicistronic messenger RNA (mRNA). Intriguingly, the major endoribonuclease RNase E, previously known to function together with small RNAs to degrade mRNA targets, is also essential for this process of mRNA activation. The exploitation of and targeted interference with regular RNA turnover described here may constitute a general route for small RNAs to rapidly activate both coding and noncoding genes. ► The bacterial small RNA SgrS posttranscriptionally activates the synthesis of YigL ► YigL is the previously hypothesized phosphatase that prevents phosphosugar toxicity ► SgrS activates yigL by a translation-independent mRNA-stabilization mechanism ► SgrS stabilizes an intermediate in the yigL mRNA decay pathway YigL, a long-sought bacterial phosphatase, regulates glucose-6-phosphate levels. A small regulatory RNA upregulates YigL synthesis by base pairing with the coding sequence of the preceding gene to interfere with endonucleolytic yigL mRNA decay.
    Keywords: Biology
    ISSN: 0092-8674
    E-ISSN: 1097-4172
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  • 9
    Language: English
    In: Science (New York, N.Y.), 30 May 2014, Vol.344(6187), pp.972-3
    Description: Argonaute proteins have emerged as the key effectors in virtually all eukaryotic small RNA-mediated gene silencing pathways (1). Central to all their activities is their association with the small guide RNAs that allow them to recognize through sequence complementarity, and in some cases also cleave, cellular transcripts.
    Keywords: DNA Cleavage ; Gene Silencing ; Argonaute Proteins -- Metabolism ; DNA -- Metabolism ; DNA, Bacterial -- Genetics ; Plasmids -- Genetics ; Prokaryotic Cells -- Metabolism ; Rhodobacter Sphaeroides -- Genetics ; Thermus Thermophilus -- Genetics
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 10
    In: Molecular Microbiology, November 2011, Vol.82(4), pp.797-806
    Description: Founded on ground‐breaking discoveries such as the operon model by Jacob and Monod more than 50 years ago, molecular microbiology is now one of the most vibrant disciplines of the life sciences. The first Mol Micro Meeting Würzburg (‘M3W’) hosted more than 160 scientists from 14 countries to exchange their latest ideas in this field of research. Divided into the four main sessions Gene Regulation, Pathogenesis, Microbial Cell Biology and Signalling, the conference provided insight into current advances and future goals and challenges.
    Keywords: Biology;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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