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Hurtado-Escobar GA, Grépinet O, Raymond P, Abed N, Velge P, Virlogeux-Payant I. H-NS is the major repressor of Salmonella Typhimurium Pef fimbriae expression. Virulence 2020; 10:849-867. [PMID: 31661351 PMCID: PMC6844306 DOI: 10.1080/21505594.2019.1682752] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Fimbriae play an important role in adhesion and are therefore essential for the interaction of bacteria with the environments they encounter. Most of them are expressed in vivo but not in vitro, thus making difficult the full characterization of these fimbriae. Here, we characterized the silencing of plasmid-encoded fimbriae (Pef) expression, encoded by the pef operon, in the worldwide pathogen Salmonella Typhimurium. We demonstrated that the nucleoid-associated proteins H-NS and Hha, and their respective paralogs StpA and YdgT, negatively regulate at pH 5.1 and pH 7.1 the transcription of the pef operon. Two promoters, PpefB and PpefA, direct the transcription of this operon. All the nucleoid-associated proteins silence the PpefB promoter and H-NS also targets the PpefA promoter. While Hha and YdgT are mainly considered as acting primarily through H-NS to modulate gene transcription, our results strongly suggest that Hha and YdgT silence pef transcription at acidic pH either by interacting with StpA or independently of H-NS and StpA. We also confirmed the previously described post-transcriptional repression of Pef fimbriae by CsrA titration via the fim mRNA and CsrB and CsrC sRNA. Finally, among all these regulators, H-NS clearly appeared as the major repressor of Pef expression. These results open new avenues of research to better characterize the regulation of these bacterial adhesive proteins and to clarify their role in the virulence of pathogens.
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Affiliation(s)
| | | | | | - Nadia Abed
- ISP, INRA, Université de Tours, Nouzilly, France
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152
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Prezza G, Heckel T, Dietrich S, Homberger C, Westermann AJ, Vogel J. Improved bacterial RNA-seq by Cas9-based depletion of ribosomal RNA reads. RNA (NEW YORK, N.Y.) 2020; 26:1069-1078. [PMID: 32345633 PMCID: PMC7373992 DOI: 10.1261/rna.075945.120] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 05/01/2020] [Indexed: 05/08/2023]
Abstract
A major challenge for RNA-seq analysis of gene expression is to achieve sufficient coverage of informative nonribosomal transcripts. In eukaryotic samples, this is typically achieved by selective oligo(dT)-priming of messenger RNAs to exclude ribosomal RNA (rRNA) during cDNA synthesis. However, this strategy is not compatible with prokaryotes in which functional transcripts are generally not polyadenylated. To overcome this, we adopted DASH (depletion of abundant sequences by hybridization), initially developed for eukaryotic cells, to improve both the sensitivity and depth of bacterial RNA-seq. DASH uses the Cas9 nuclease to remove unwanted cDNA sequences prior to library amplification. We report the design, evaluation, and optimization of DASH experiments for standard bacterial short-read sequencing approaches, including software for automated guide RNA (gRNA) design for Cas9-mediated cleavage in bacterial rDNA sequences. Using these gRNA pools, we effectively removed rRNA reads (56%-86%) in RNA-seq libraries from two different model bacteria, the Gram-negative pathogen Salmonella enterica and the anaerobic gut commensal Bacteroides thetaiotaomicron DASH works robustly, even with subnanogram amounts of input RNA. Its efficiency, high sensitivity, ease of implementation, and low cost (∼$5 per sample) render DASH an attractive alternative to rRNA removal protocols, in particular for material-constrained studies where conventional ribodepletion techniques fail.
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Affiliation(s)
- Gianluca Prezza
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, 97080, Germany
| | - Tobias Heckel
- Core Unit Systems Medicine, University of Würzburg, Würzburg, 97080, Germany
| | - Sascha Dietrich
- Core Unit Systems Medicine, University of Würzburg, Würzburg, 97080, Germany
| | - Christina Homberger
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, 97080, Germany
| | - Alexander J Westermann
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, 97080, Germany
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, 97080, Germany
| | - Jörg Vogel
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, 97080, Germany
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, 97080, Germany
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153
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Honeycutt JD, Wenner N, Li Y, Brewer SM, Massis LM, Brubaker SW, Chairatana P, Owen SV, Canals R, Hinton JCD, Monack DM. Genetic variation in the MacAB-TolC efflux pump influences pathogenesis of invasive Salmonella isolates from Africa. PLoS Pathog 2020; 16:e1008763. [PMID: 32834002 PMCID: PMC7446830 DOI: 10.1371/journal.ppat.1008763] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/30/2020] [Indexed: 01/23/2023] Open
Abstract
The various sub-species of Salmonella enterica cause a range of disease in human hosts. The human-adapted Salmonella enterica serovar Typhi enters the gastrointestinal tract and invades systemic sites to cause enteric (typhoid) fever. In contrast, most non-typhoidal serovars of Salmonella are primarily restricted to gut tissues. Across Africa, invasive non-typhoidal Salmonella (iNTS) have emerged with an ability to spread beyond the gastrointestinal tract and cause systemic bloodstream infections with increased morbidity and mortality. To investigate this evolution in pathogenesis, we compared the genomes of African iNTS isolates with other Salmonella enterica serovar Typhimurium and identified several macA and macB gene variants unique to African iNTS. MacAB forms a tripartite efflux pump with TolC and is implicated in Salmonella pathogenesis. We show that macAB transcription is upregulated during macrophage infection and after antimicrobial peptide exposure, with macAB transcription being supported by the PhoP/Q two-component system. Constitutive expression of macAB improves survival of Salmonella in the presence of the antimicrobial peptide C18G. Furthermore, these macAB variants affect replication in macrophages and influence fitness during colonization of the murine gastrointestinal tract. Importantly, the infection outcome resulting from these macAB variants depends upon both the Salmonella Typhimurium genetic background and the host gene Nramp1, an important determinant of innate resistance to intracellular bacterial infection. The variations we have identified in the MacAB-TolC efflux pump in African iNTS may reflect evolution within human host populations that are compromised in their ability to clear intracellular Salmonella infections.
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Affiliation(s)
- Jared D. Honeycutt
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Nicolas Wenner
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Yan Li
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Susan M. Brewer
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Liliana M. Massis
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Sky W. Brubaker
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Phoom Chairatana
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Siân V. Owen
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rocío Canals
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Jay C. D. Hinton
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Denise M. Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
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154
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A high-resolution transcriptome map identifies small RNA regulation of metabolism in the gut microbe Bacteroides thetaiotaomicron. Nat Commun 2020; 11:3557. [PMID: 32678091 PMCID: PMC7366714 DOI: 10.1038/s41467-020-17348-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/23/2020] [Indexed: 12/15/2022] Open
Abstract
Bacteria of the genus Bacteroides are common members of the human intestinal microbiota and important degraders of polysaccharides in the gut. Among them, the species Bacteroides thetaiotaomicron has emerged as the model organism for functional microbiota research. Here, we use differential RNA sequencing (dRNA-seq) to generate a single-nucleotide resolution transcriptome map of B. thetaiotaomicron grown under defined laboratory conditions. An online browser, called ‘Theta-Base’ (www.helmholtz-hiri.de/en/datasets/bacteroides), is launched to interrogate the obtained gene expression data and annotations of ~4500 transcription start sites, untranslated regions, operon structures, and 269 noncoding RNA elements. Among the latter is GibS, a conserved, 145 nt-long small RNA that is highly expressed in the presence of N-acetyl-D-glucosamine as sole carbon source. We use computational predictions and experimental data to determine the secondary structure of GibS and identify its target genes. Our results indicate that sensing of N-acetyl-D-glucosamine induces GibS expression, which in turn modifies the transcript levels of metabolic enzymes. Bacteroides thetaiotaomicron is a human gut microbe and an emergent model organism. Here, Ryan et al. generate single-nucleotide resolution RNA-seq data for this bacterium and map transcription start sites and noncoding RNAs, one of which modulates expression of metabolic enzymes.
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155
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Nguyen BD, Cuenca V M, Hartl J, Gül E, Bauer R, Meile S, Rüthi J, Margot C, Heeb L, Besser F, Escriva PP, Fetz C, Furter M, Laganenka L, Keller P, Fuchs L, Christen M, Porwollik S, McClelland M, Vorholt JA, Sauer U, Sunagawa S, Christen B, Hardt WD. Import of Aspartate and Malate by DcuABC Drives H 2/Fumarate Respiration to Promote Initial Salmonella Gut-Lumen Colonization in Mice. Cell Host Microbe 2020; 27:922-936.e6. [PMID: 32416061 PMCID: PMC7292772 DOI: 10.1016/j.chom.2020.04.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/16/2020] [Accepted: 04/14/2020] [Indexed: 12/13/2022]
Abstract
Initial enteropathogen growth in the microbiota-colonized gut is poorly understood. Salmonella Typhimurium is metabolically adaptable and can harvest energy by anaerobic respiration using microbiota-derived hydrogen (H2) as an electron donor and fumarate as an electron acceptor. As fumarate is scarce in the gut, the source of this electron acceptor is unclear. Here, transposon sequencing analysis along the colonization trajectory of S. Typhimurium implicates the C4-dicarboxylate antiporter DcuABC in early murine gut colonization. In competitive colonization assays, DcuABC and enzymes that convert the C4-dicarboxylates aspartate and malate into fumarate (AspA, FumABC), are required for fumarate/H2-dependent initial growth. Thus, S. Typhimurium obtains fumarate by DcuABC-mediated import and conversion of L-malate and L-aspartate. Fumarate reduction yields succinate, which is exported by DcuABC in exchange for L-aspartate and L-malate. This cycle allows S. Typhimurium to harvest energy by H2/fumarate respiration in the microbiota-colonized gut. This strategy may also be relevant for commensal E. coli diminishing the S. Typhimurium infection.
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Affiliation(s)
- Bidong D Nguyen
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | | | - Johannes Hartl
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Ersin Gül
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Rebekka Bauer
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Susanne Meile
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Joel Rüthi
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Céline Margot
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Laura Heeb
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Franziska Besser
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Pau Pérez Escriva
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Céline Fetz
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Markus Furter
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Leanid Laganenka
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Philipp Keller
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Lea Fuchs
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Matthias Christen
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA
| | - Julia A Vorholt
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Uwe Sauer
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland
| | - Shinichi Sunagawa
- Institute of Microbiology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland.
| | - Beat Christen
- Institute of Molecular Systems Biology, D-BIOL, ETH Zürich, 8093 Zürich, Switzerland.
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156
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Combining Whole-Genome Sequencing and Multimodel Phenotyping To Identify Genetic Predictors of Salmonella Virulence. mSphere 2020; 5:5/3/e00293-20. [PMID: 32522778 PMCID: PMC7289705 DOI: 10.1128/msphere.00293-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella comprises more than 2,600 serovars. Very few environmental and uncommon serovars have been characterized for their potential role in virulence and human infections. A complementary in vitro and in vivo systematic high-throughput analysis of virulence was used to elucidate the association between genetic and phenotypic variations across Salmonella isolates. The goal was to develop a strategy for the classification of isolates as a benchmark and predict virulence levels of isolates. Thirty-five phylogenetically distant strains of unknown virulence were selected from the Salmonella Foodborne Syst-OMICS (SalFoS) collection, representing 34 different serovars isolated from various sources. Isolates were evaluated for virulence in 4 complementary models of infection to compare virulence traits with the genomics data, including interactions with human intestinal epithelial cells, human macrophages, and amoeba. In vivo testing was conducted using the mouse model of Salmonella systemic infection. Significant correlations were identified between the different models. We identified a collection of novel hypothetical and conserved proteins associated with isolates that generate a high burden. We also showed that blind prediction of virulence of 33 additional strains based on the pan-genome was high in the mouse model of systemic infection (82% agreement) and in the human epithelial cell model (74% agreement). These complementary approaches enabled us to define virulence potential in different isolates and present a novel strategy for risk assessment of specific strains and for better monitoring and source tracking during outbreaks.IMPORTANCE Salmonella species are bacteria that are a major source of foodborne disease through contamination of a diversity of foods, including meat, eggs, fruits, nuts, and vegetables. More than 2,600 different Salmonella enterica serovars have been identified, and only a few of them are associated with illness in humans. Despite the fact that they are genetically closely related, there is enormous variation in the virulence of different isolates of Salmonella enterica Identification of foodborne pathogens is a lengthy process based on microbiological, biochemical, and immunological methods. Here, we worked toward new ways of integrating whole-genome sequencing (WGS) approaches into food safety practices. We used WGS to build associations between virulence and genetic diversity within 83 Salmonella isolates representing 77 different Salmonella serovars. Our work demonstrates the potential of combining a genomics approach and virulence tests to improve the diagnostics and assess risk of human illness associated with specific Salmonella isolates.
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157
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Plugging Small RNAs into the Network. mSystems 2020; 5:5/3/e00422-20. [PMID: 32487744 PMCID: PMC8534730 DOI: 10.1128/msystems.00422-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Small RNAs (sRNAs) have been discovered in every bacterium examined and have been shown to play important roles in the regulation of a diverse range of behaviors, from metabolism to infection. However, despite a wide range of available techniques for discovering and validating sRNA regulatory interactions, only a minority of these molecules have been well characterized. In part, this is due to the nature of posttranscriptional regulation: the activity of an sRNA depends on the state of the transcriptome as a whole, so characterization is best carried out under the conditions in which it is naturally active. In this issue of mSystems, Arrieta-Ortiz and colleagues (M. L. Arrieta-Ortiz, C. Hafemeister, B. Shuster, N. S. Baliga, et al., mSystems 5:e00057-20, 2020, https://doi.org/10.1128/mSystems.00057-20) present a network inference approach based on estimating sRNA activity across transcriptomic compendia. This shows promise not only for identifying new sRNA regulatory interactions but also for pinpointing the conditions in which these interactions occur, providing a new avenue toward functional characterization of sRNAs.
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158
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Ferrand A, Vergalli J, Pagès JM, Davin-Regli A. An Intertwined Network of Regulation Controls Membrane Permeability Including Drug Influx and Efflux in Enterobacteriaceae. Microorganisms 2020; 8:E833. [PMID: 32492979 PMCID: PMC7355843 DOI: 10.3390/microorganisms8060833] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 12/19/2022] Open
Abstract
The transport of small molecules across membranes is a pivotal step for controlling the drug concentration into the bacterial cell and it efficiently contributes to the antibiotic susceptibility in Enterobacteriaceae. Two types of membrane transports, passive and active, usually represented by porins and efflux pumps, are involved in this process. Importantly, the expression of these transporters and channels are modulated by an armamentarium of tangled regulatory systems. Among them, Helix-turn-Helix (HTH) family regulators (including the AraC/XylS family) and the two-component systems (TCS) play a key role in bacterial adaptation to environmental stresses and can manage a decrease of porin expression associated with an increase of efflux transporters expression. In the present review, we highlight some recent genetic and functional studies that have substantially contributed to our better understanding of the sophisticated mechanisms controlling the transport of small solutes (antibiotics) across the membrane of Enterobacteriaceae. This information is discussed, taking into account the worrying context of clinical antibiotic resistance and fitness of bacterial pathogens. The localization and relevance of mutations identified in the respective regulation cascades in clinical resistant strains are discussed. The possible way to bypass the membrane/transport barriers is described in the perspective of developing new therapeutic targets to combat bacterial resistance.
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Affiliation(s)
| | | | | | - Anne Davin-Regli
- UMR_MD1, U-1261, Aix-Marseille University, INSERM, SSA, IRBA, MCT, Faculté de Pharmacie, 27 Bd Jean Moulin, 13385 Marseille CEDEX 05, France; (A.F.); (J.V.); (J.-M.P.)
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159
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Salvail H, Groisman EA. The phosphorelay BarA/SirA activates the non-cognate regulator RcsB in Salmonella enterica. PLoS Genet 2020; 16:e1008722. [PMID: 32392214 PMCID: PMC7241856 DOI: 10.1371/journal.pgen.1008722] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/21/2020] [Accepted: 03/18/2020] [Indexed: 11/18/2022] Open
Abstract
To survive an environmental stress, organisms must detect the stress and mount an appropriate response. One way that bacteria do so is by phosphorelay systems that respond to a stress by activating a regulator that modifies gene expression. To ensure an appropriate response, a given regulator is typically activated solely by its cognate phosphorelay protein(s). However, we now report that the regulator RcsB is activated by both cognate and non-cognate phosphorelay proteins, depending on the condition experienced by the bacterium Salmonella enterica serovar Typhimurium. The RcsC and RcsD proteins form a phosphorelay that activates their cognate regulator RcsB in response to outer membrane stress and cell wall perturbations, conditions Salmonella experiences during infection. Surprisingly, the non-cognate phosphorelay protein BarA activates RcsB during logarithmic growth in Luria-Bertani medium in three ways. That is, BarA’s cognate regulator SirA promotes transcription of the rcsDB operon; the SirA-dependent regulatory RNAs CsrB and CsrC further increase RcsB-activated gene transcription; and BarA activates RcsB independently of the RcsC, RcsD, and SirA proteins. Activation of a regulator by multiple sensors broadens the spectrum of environments in which a set of genes is expressed without evolving binding sites for different regulators at each of these genes. The phosphorelay is a form of signal transduction used by organisms in all three domains of life. Typically, a phosphorelay consists of sensor proteins that respond to specific signals by activating a cognate regulatory protein that alters gene expression. Phosphorelays exhibit specificity towards their cognate regulators, thereby ensuring that any changes in gene expression help an organism cope with the experienced stress (and not with an unrelated stress). However, we now report that the regulator RcsB is activated by both cognate and non-cognate phosphorelay proteins in the bacterium Salmonella enterica serovar Typhimurium. The phosphorelay proteins RcsC and RcsD activate RcsB upon cell envelope perturbations, whereas the non-cognate phosphorelay protein BarA activates RcsB during rapid growth in Luria-Bertani medium. Our findings establish that BarA controls gene expression via both its cognate regulator SirA and the non-cognate regulator RcsB. In addition, they demonstrate that RcsB controls gene expression in response to multiple signals detected by the RcsC, RcsD, and BarA proteins.
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Affiliation(s)
- Hubert Salvail
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
- * E-mail:
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160
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161
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Decoding the stoichiometric composition and organisation of bacterial metabolosomes. Nat Commun 2020; 11:1976. [PMID: 32332738 PMCID: PMC7181861 DOI: 10.1038/s41467-020-15888-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 03/31/2020] [Indexed: 01/08/2023] Open
Abstract
Some enteric bacteria including Salmonella have evolved the propanediol-utilising microcompartment (Pdu MCP), a specialised proteinaceous organelle that is essential for 1,2-propanediol degradation and enteric pathogenesis. Pdu MCPs are a family of bacterial microcompartments that are self-assembled from hundreds of proteins within the bacterial cytosol. Here, we seek a comprehensive understanding of the stoichiometric composition and organisation of Pdu MCPs. We obtain accurate stoichiometry of shell proteins and internal enzymes of the natural Pdu MCP by QconCAT-driven quantitative mass spectrometry. Genetic deletion of the major shell protein and absolute quantification reveal the stoichiometric and structural remodelling of metabolically functional Pdu MCPs. Decoding the precise protein stoichiometry allows us to develop an organisational model of the Pdu metabolosome. The structural insights into the Pdu MCP are critical for both delineating the general principles underlying bacterial organelle formation, structural robustness and function, and repurposing natural microcompartments using synthetic biology for biotechnological applications. Enteric pathogens such as Salmonella depend on propanediol-utilising microcompartments (Pdu MCP), which self-assemble from cytosolic proteins. Using mass spectrometry-based absolute quantification, the authors here define the protein stoichiometry and propose an organizational model of a Salmonella Pdu MCP.
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162
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Lerminiaux NA, MacKenzie KD, Cameron ADS. Salmonella Pathogenicity Island 1 (SPI-1): The Evolution and Stabilization of a Core Genomic Type Three Secretion System. Microorganisms 2020; 8:microorganisms8040576. [PMID: 32316180 PMCID: PMC7232297 DOI: 10.3390/microorganisms8040576] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 11/16/2022] Open
Abstract
Salmonella Pathogenicity Island 1 (SPI-1) encodes a type three secretion system (T3SS), effector proteins, and associated transcription factors that together enable invasion of epithelial cells in animal intestines. The horizontal acquisition of SPI-1 by the common ancestor of all Salmonella is considered a prime example of how gene islands potentiate the emergence of new pathogens with expanded niche ranges. However, the evolutionary history of SPI-1 has attracted little attention. Here, we apply phylogenetic comparisons across the family Enterobacteriaceae to examine the history of SPI-1, improving the resolution of its boundaries and unique architecture by identifying its composite gene modules. SPI-1 is located between the core genes fhlA and mutS, a hotspot for the gain and loss of horizontally acquired genes. Despite the plasticity of this locus, SPI-1 demonstrates stable residency of many tens of millions of years in a host genome, unlike short-lived homologous T3SS and effector islands including Escherichia ETT2, Yersinia YSA, Pantoea PSI-2, Sodalis SSR2, and Chromobacterium CPI-1. SPI-1 employs a unique series of regulatory switches, starting with the dedicated transcription factors HilC and HilD, and flowing through the central SPI-1 regulator HilA. HilA is shared with other T3SS, but HilC and HilD may have their evolutionary origins in Salmonella. The hilA, hilC, and hilD gene promoters are the most AT-rich DNA in SPI-1, placing them under tight control by the transcriptional repressor H-NS. In all Salmonella lineages, these three promoters resist amelioration towards the genomic average, ensuring strong repression by H-NS. Hence, early development of a robust and well-integrated regulatory network may explain the evolutionary stability of SPI-1 compared to T3SS gene islands in other species.
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Affiliation(s)
- Nicole A. Lerminiaux
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Keith D. MacKenzie
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Andrew D. S. Cameron
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
- Correspondence:
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Cervantes-Rivera R, Tronnet S, Puhar A. Complete genome sequence and annotation of the laboratory reference strain Shigella flexneri serotype 5a M90T and genome-wide transcriptional start site determination. BMC Genomics 2020; 21:285. [PMID: 32252626 PMCID: PMC7132871 DOI: 10.1186/s12864-020-6565-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 02/07/2020] [Indexed: 01/19/2023] Open
Abstract
Background Shigella is a Gram-negative facultative intracellular bacterium that causes bacillary dysentery in humans. Shigella invades cells of the colonic mucosa owing to its virulence plasmid-encoded Type 3 Secretion System (T3SS), and multiplies in the target cell cytosol. Although the laboratory reference strain S. flexneri serotype 5a M90T has been extensively used to understand the molecular mechanisms of pathogenesis, its complete genome sequence is not available, thereby greatly limiting studies employing high-throughput sequencing and systems biology approaches. Results We have sequenced, assembled, annotated and manually curated the full genome of S. flexneri 5a M90T. This yielded two complete circular contigs, the chromosome and the virulence plasmid (pWR100). To obtain the genome sequence, we have employed long-read PacBio DNA sequencing followed by polishing with Illumina RNA-seq data. This provides a new hybrid strategy to prepare gapless, highly accurate genome sequences, which also cover AT-rich tracks or repetitive sequences that are transcribed. Furthermore, we have performed genome-wide analysis of transcriptional start sites (TSS) and determined the length of 5′ untranslated regions (5′-UTRs) at typical culture conditions for the inoculum of in vitro infection experiments. We identified 6723 primary TSS (pTSS) and 7328 secondary TSS (sTSS). The S. flexneri 5a M90T annotated genome sequence and the transcriptional start sites are integrated into RegulonDB (http://regulondb.ccg.unam.mx) and RSAT (http://embnet.ccg.unam.mx/rsat/) databases to use their analysis tools in the S. flexneri 5a M90T genome. Conclusions We provide the first complete genome for S. flexneri serotype 5a, specifically the laboratory reference strain M90T. Our work opens the possibility of employing S. flexneri M90T in high-quality systems biology studies such as transcriptomic and differential expression analyses or in genome evolution studies. Moreover, the catalogue of TSS that we report here can be used in molecular pathogenesis studies as a resource to know which genes are transcribed before infection of host cells. The genome sequence, together with the analysis of transcriptional start sites, is also a valuable tool for precise genetic manipulation of S. flexneri 5a M90T. Further, we present a new hybrid strategy to prepare gapless, highly accurate genome sequences. Unlike currently used hybrid strategies combining long- and short-read DNA sequencing technologies to maximize accuracy, our workflow using long-read DNA sequencing and short-read RNA sequencing provides the added value of using non-redundant technologies, which yield distinct, exploitable datasets.
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Affiliation(s)
- Ramón Cervantes-Rivera
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), 901 87 Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), 901 87, Umeå, Sweden.,Department of Molecular Biology, Umeå University, 901 87, Umeå, Sweden
| | - Sophie Tronnet
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), 901 87 Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), 901 87, Umeå, Sweden.,Department of Molecular Biology, Umeå University, 901 87, Umeå, Sweden
| | - Andrea Puhar
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), 901 87 Umeå, Sweden. .,Umeå Centre for Microbial Research (UCMR), 901 87, Umeå, Sweden. .,Department of Molecular Biology, Umeå University, 901 87, Umeå, Sweden.
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164
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Atypical Salmonella enterica Serovars in Murine and Human Macrophage Infection Models. Infect Immun 2020; 88:IAI.00353-19. [PMID: 32014897 DOI: 10.1128/iai.00353-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 01/28/2020] [Indexed: 11/20/2022] Open
Abstract
Nontyphoidal Salmonella species are globally disseminated pathogens and are the predominant cause of gastroenteritis. The pathogenesis of salmonellosis has been extensively studied using in vivo murine models and cell lines, typically challenged with Salmonella enterica serovar Typhimurium. Although S. enterica serovars Enteritidis and Typhimurium are responsible for most of the human infections reported to the Centers for Disease Control and Prevention (CDC), several other serovars also contribute to clinical cases of salmonellosis. Despite their epidemiological importance, little is known about their infection phenotypes. Here, we report the virulence characteristics and genomes of 10 atypical S. enterica serovars linked to multistate foodborne outbreaks in the United States. We show that the murine RAW 264.7 macrophage model of infection is unsuitable for inferring human-relevant differences in nontyphoidal Salmonella infections, whereas differentiated human THP-1 macrophages allowed these isolates to be further characterized in a more human-relevant context.
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165
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Wang C, Chao Y, Matera G, Gao Q, Vogel J. The conserved 3' UTR-derived small RNA NarS mediates mRNA crossregulation during nitrate respiration. Nucleic Acids Res 2020; 48:2126-2143. [PMID: 31863581 PMCID: PMC7038943 DOI: 10.1093/nar/gkz1168] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 11/27/2019] [Accepted: 12/02/2019] [Indexed: 12/13/2022] Open
Abstract
Small noncoding RNAs (sRNAs) from mRNA 3′ UTRs seem to present a previously unrecognized layer of bacterial post-transcriptional control whereby mRNAs influence each other's expression, independently of transcriptional control. Studies in Escherichia coli and Salmonella enterica showed that such sRNAs are natural products of RNase E-mediated mRNA decay and associate with major RNA-binding proteins (RBPs) such as Hfq and ProQ. If so, there must be additional sRNAs from mRNAs that accumulate only under specific physiological conditions. We test this prediction by characterizing candidate NarS that represents the 3′ UTR of nitrate transporter NarK whose gene is silent during standard aerobic growth. We find that NarS acts by Hfq-dependent base pairing to repress the synthesis of the nitrite transporter, NirC, resulting in mRNA cross-regulation of nitrate and nitrite transporter genes. Interestingly, the NarS-mediated repression selectively targets the nirC cistron of the long nirBDC-cysG operon, an observation that we rationalize as a mechanism to protect the bacterial cytoplasm from excessive nitrite toxicity during anaerobic respiration with abundant nitrate. Our successful functional assignment of a 3′ UTR sRNA from a non-standard growth condition supports the notion that mRNA crossregulation is more pervasive than currently appreciated.
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Affiliation(s)
- Chuan Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200033, PR China.,Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany
| | - Yanjie Chao
- Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany.,Howard Hughes Medical Institute, Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Gianluca Matera
- Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany
| | - Qian Gao
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200033, PR China
| | - Jörg Vogel
- Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany.,Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Center for Infection Research (HZI), D-97080 Würzburg, Germany
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166
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Hör J, Matera G, Vogel J, Gottesman S, Storz G. Trans-Acting Small RNAs and Their Effects on Gene Expression in Escherichia coli and Salmonella enterica. EcoSal Plus 2020; 9:10.1128/ecosalplus.ESP-0030-2019. [PMID: 32213244 PMCID: PMC7112153 DOI: 10.1128/ecosalplus.esp-0030-2019] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Indexed: 12/20/2022]
Abstract
The last few decades have led to an explosion in our understanding of the major roles that small regulatory RNAs (sRNAs) play in regulatory circuits and the responses to stress in many bacterial species. Much of the foundational work was carried out with Escherichia coli and Salmonella enterica serovar Typhimurium. The studies of these organisms provided an overview of how the sRNAs function and their impact on bacterial physiology, serving as a blueprint for sRNA biology in many other prokaryotes. They also led to the development of new technologies. In this chapter, we first summarize how these sRNAs were identified, defining them in the process. We discuss how they are regulated and how they act and provide selected examples of their roles in regulatory circuits and the consequences of this regulation. Throughout, we summarize the methodologies that were developed to identify and study the regulatory RNAs, most of which are applicable to other bacteria. Newly updated databases of the known sRNAs in E. coli K-12 and S. enterica Typhimurium SL1344 serve as a reference point for much of the discussion and, hopefully, as a resource for readers and for future experiments to address open questions raised in this review.
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Affiliation(s)
- Jens Hör
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Gianluca Matera
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Jörg Vogel
- Helmholtz Institute for RNA-based Infection Research (HIRI), 97080 Würzburg, Germany
- Institute of Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Susan Gottesman
- Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892
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167
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Hudeček O, Benoni R, Reyes-Gutierrez PE, Culka M, Šanderová H, Hubálek M, Rulíšek L, Cvačka J, Krásný L, Cahová H. Dinucleoside polyphosphates act as 5'-RNA caps in bacteria. Nat Commun 2020; 11:1052. [PMID: 32103016 PMCID: PMC7044304 DOI: 10.1038/s41467-020-14896-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 02/07/2020] [Indexed: 12/12/2022] Open
Abstract
It has been more than 50 years since the discovery of dinucleoside polyphosphates (NpnNs) and yet their roles and mechanisms of action remain unclear. Here, we show that both methylated and non-methylated NpnNs serve as RNA caps in Escherichia coli. NpnNs are excellent substrates for T7 and E. coli RNA polymerases (RNAPs) and efficiently initiate transcription. We demonstrate, that the E. coli enzymes RNA 5′-pyrophosphohydrolase (RppH) and bis(5′-nucleosyl)-tetraphosphatase (ApaH) are able to remove the NpnN-caps from RNA. ApaH is able to cleave all NpnN-caps, while RppH is unable to cleave the methylated forms suggesting that the methylation adds an additional layer to RNA stability regulation. Our work introduces a different perspective on the chemical structure of RNA in prokaryotes and on the role of RNA caps. We bring evidence that small molecules, such as NpnNs are incorporated into RNA and may thus influence the cellular metabolism and RNA turnover. Nicotinamide adenine dinucleotide and coenzyme A serve as a 5′-cap of prokaryotic RNA. Here the authors report that methylated and non-methylated dinucleoside polyphosphates (NpnNs) exist as Escherichia coli RNA caps which can be cleaved by 5′-pyrophosphohydrolase (RppH) and bis(5′-nucleosyl)-tetraphosphatase (ApaH).
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Affiliation(s)
- Oldřich Hudeček
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Roberto Benoni
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Paul E Reyes-Gutierrez
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Martin Culka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Hana Šanderová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Martin Hubálek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Josef Cvačka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic
| | - Libor Krásný
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Hana Cahová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nam. 2, 16610, Prague 6, Czech Republic.
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168
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Stårsta M, Hammarlöf DL, Wäneskog M, Schlegel S, Xu F, Heden Gynnå A, Borg M, Herschend S, Koskiniemi S. RHS-elements function as type II toxin-antitoxin modules that regulate intra-macrophage replication of Salmonella Typhimurium. PLoS Genet 2020; 16:e1008607. [PMID: 32053596 PMCID: PMC7043789 DOI: 10.1371/journal.pgen.1008607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 02/26/2020] [Accepted: 01/12/2020] [Indexed: 11/19/2022] Open
Abstract
RHS elements are components of conserved toxin-delivery systems, wide-spread within the bacterial kingdom and some of the most positively selected genes known. However, very little is known about how Rhs toxins affect bacterial biology. Salmonella Typhimurium contains a full-length rhs gene and an adjacent orphan rhs gene, which lacks the conserved delivery part of the Rhs protein. Here we show that, in addition to the conventional delivery, Rhs toxin-antitoxin pairs encode for functional type-II toxin-antitoxin (TA) loci that regulate S. Typhimurium proliferation within macrophages. Mutant S. Typhimurium cells lacking both Rhs toxins proliferate 2-times better within macrophages, mainly because of an increased growth rate. Thus, in addition to providing strong positive selection for the rhs loci under conditions when there is little or no toxin delivery, internal expression of the toxin-antitoxin system regulates growth in the stressful environment found inside macrophages. Bacteria that reside and multiply inside of phagocytic cells are hard to treat with common antibiotics, partly because subpopulations of bacteria are non-growing. Very little is known about how bacteria regulate their growth in the phagocytic vesicle. We show that RHS elements, previously known to function as mobilizable toxins that inhibit growth of neighboring bacteria, also function as internally expressed toxin-antitoxin systems that regulate Salmonella Typhimurium growth in macrophages. RHS elements were discovered more than 30 years ago, but their role in biology has long remained unclear even though they are some of the most positively selected genes known. Our results suggest an explanation to why rhs genes are under such strong positive selection in addition to suggesting a novel function for these toxins in regulating bacterial growth.
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Affiliation(s)
- Magnus Stårsta
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Disa L. Hammarlöf
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Marcus Wäneskog
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Susan Schlegel
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Feifei Xu
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Arvid Heden Gynnå
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Malin Borg
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sten Herschend
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
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169
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The evolution of MarR family transcription factors as counter-silencers in regulatory networks. Curr Opin Microbiol 2020; 55:1-8. [PMID: 32044654 DOI: 10.1016/j.mib.2020.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/29/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022]
Abstract
Gene duplication facilitates the evolution of biological complexity, as one copy of a gene retains its original function while a duplicate copy can acquire mutations that would otherwise diminish fitness. Duplication has played a particularly important role in the evolution of regulatory networks by permitting novel regulatory interactions and responses to stimuli. The diverse MarR family of transcription factors (MFTFs) illustrate this concept, ranging from highly specific repressors of single operons to pleiotropic global regulators controlling hundreds of genes. MFTFs are often genetically and functionally linked to antimicrobial efflux systems. However, the SlyA MFTF lineage in the Enterobacteriaceae plays little or no role in regulating efflux but rather functions as transcriptional counter-silencers, which alleviate xenogeneic silencing of horizontally acquired genes and facilitate bacterial evolution by horizontal gene transfer. This review will explore recent advances in our understanding of MFTF traits that have contributed to their functional evolution.
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170
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Owen SV, Canals R, Wenner N, Hammarlöf DL, Kröger C, Hinton JCD. A window into lysogeny: revealing temperate phage biology with transcriptomics. Microb Genom 2020; 6:e000330. [PMID: 32022660 PMCID: PMC7067206 DOI: 10.1099/mgen.0.000330] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/28/2019] [Indexed: 12/17/2022] Open
Abstract
Prophages are integrated phage elements that are a pervasive feature of bacterial genomes. The fitness of bacteria is enhanced by prophages that confer beneficial functions such as virulence, stress tolerance or phage resistance, and these functions are encoded by 'accessory' or 'moron' loci. Whilst the majority of phage-encoded genes are repressed during lysogeny, accessory loci are often highly expressed. However, it is challenging to identify novel prophage accessory loci from DNA sequence data alone. Here, we use bacterial RNA-seq data to examine the transcriptional landscapes of five Salmonella prophages. We show that transcriptomic data can be used to heuristically enrich for prophage features that are highly expressed within bacterial cells and represent functionally important accessory loci. Using this approach, we identify a novel antisense RNA species in prophage BTP1, STnc6030, which mediates superinfection exclusion of phage BTP1. Bacterial transcriptomic datasets are a powerful tool to explore the molecular biology of temperate phages.
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Affiliation(s)
- Siân V. Owen
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Rocío Canals
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
- Present address: GSK Vaccines Institute for Global Health, Siena, Italy
| | - Nicolas Wenner
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Disa L. Hammarlöf
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
- Science for Life Laboratory, KTH, Stockholm, Sweden
| | - Carsten Kröger
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Jay C. D. Hinton
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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171
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Lê-Bury G, Deschamps C, Kizilyaprak C, Blanchard W, Daraspe J, Dumas A, Gordon MA, Hinton JCD, Humbel BM, Niedergang F. Increased intracellular survival of Salmonella Typhimurium ST313 in HIV-1-infected primary human macrophages is not associated with Salmonella hijacking the HIV compartment. Biol Cell 2020; 112:92-101. [PMID: 31922615 DOI: 10.1111/boc.201900055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 11/28/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Non-typhoidal Salmonella (NTS) causes a severe invasive syndrome (iNTS disease) described in HIV-positive adults. The impact of HIV-1 on Salmonella pathogenesis and the molecular basis for the differences between these bacteria and classical diarrhoeal S. Typhimurium remains unclear. RESULTS Here, we show that iNTS-associated S. Typhimurium Sequence Type 313 (ST313) bacteria show greater intracellular survival in primary human macrophages, compared with a 'classical' diarrhoeal S. Typhimurium ST19 isolate. The increased intracellular survival phenotype of ST313 is more pronounced in HIV-infected macrophages. We explored the possibility that the bacteria take advantage of the HIV-associated viral-containing compartments created in human macrophages that have low pH. Confocal fluorescence microscopy and focussed ion beam-scanning electron microscopy tomography showed that Salmonella did not co-localise extensively with HIV-positive compartments. CONCLUSION The capacity of ST313 bacteria to survive better than ST19 bacteria within primary human macrophages is enhanced in cells pre-infected with HIV-1. Our results indicate that the ST313 bacteria do not directly benefit from the niche created by the virus in HIV-1-infected macrophages, and that they might take advantage from a more globally modified host cell. SIGNIFICANCE A better understanding of the interplay between HIV-1 and Salmonella is important not only for these bacteria but also for other opportunistic pathogens.
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Affiliation(s)
- G Lê-Bury
- Institut Cochin, Université de Paris, INSERM, U1016, CNRS, UMR 8104, Paris, F-75014, France
| | - C Deschamps
- Institut Cochin, Université de Paris, INSERM, U1016, CNRS, UMR 8104, Paris, F-75014, France
| | - C Kizilyaprak
- Faculté de Biologie et de Médecine, Electron Microscopy Facility, Université de Lausanne, Lausanne, Switzerland
| | - W Blanchard
- Faculté de Biologie et de Médecine, Electron Microscopy Facility, Université de Lausanne, Lausanne, Switzerland
| | - J Daraspe
- Faculté de Biologie et de Médecine, Electron Microscopy Facility, Université de Lausanne, Lausanne, Switzerland
| | - A Dumas
- Institut Cochin, Université de Paris, INSERM, U1016, CNRS, UMR 8104, Paris, F-75014, France
| | - M A Gordon
- Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.,Malawi-Liverpool-Welcome Trust B=Clinical Research Programme, Malawi
| | - J C D Hinton
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - B M Humbel
- Faculté de Biologie et de Médecine, Electron Microscopy Facility, Université de Lausanne, Lausanne, Switzerland.,IMG, Okinawa Institute of Science and Technology, Onna-son, Okinawa, Japan
| | - F Niedergang
- Institut Cochin, Université de Paris, INSERM, U1016, CNRS, UMR 8104, Paris, F-75014, France
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172
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Lin L, Zheng Q, Lin J, Yuk HG, Guo L. Immuno- and nucleic acid-based current technique for Salmonella detection in food. Eur Food Res Technol 2020. [DOI: 10.1007/s00217-019-03423-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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173
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Muhammad II, Kong SL, Akmar Abdullah SN, Munusamy U. RNA-seq and ChIP-seq as Complementary Approaches for Comprehension of Plant Transcriptional Regulatory Mechanism. Int J Mol Sci 2019; 21:E167. [PMID: 31881735 PMCID: PMC6981605 DOI: 10.3390/ijms21010167] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 12/19/2019] [Accepted: 12/23/2019] [Indexed: 02/07/2023] Open
Abstract
The availability of data produced from various sequencing platforms offer the possibility to answer complex questions in plant research. However, drawbacks can arise when there are gaps in the information generated, and complementary platforms are essential to obtain more comprehensive data sets relating to specific biological process, such as responses to environmental perturbations in plant systems. The investigation of transcriptional regulation raises different challenges, particularly in associating differentially expressed transcription factors with their downstream responsive genes. In this paper, we discuss the integration of transcriptional factor studies through RNA sequencing (RNA-seq) and Chromatin Immunoprecipitation sequencing (ChIP-seq). We show how the data from ChIP-seq can strengthen information generated from RNA-seq in elucidating gene regulatory mechanisms. In particular, we discuss how integration of ChIP-seq and RNA-seq data can help to unravel transcriptional regulatory networks. This review discusses recent advances in methods for studying transcriptional regulation using these two methods. It also provides guidelines for making choices in selecting specific protocols in RNA-seq pipelines for genome-wide analysis to achieve more detailed characterization of specific transcription regulatory pathways via ChIP-seq.
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Affiliation(s)
- Isiaka Ibrahim Muhammad
- Laboratory of Plantation Science and Technology, Institute of Plantation Studies, Universiti Putra Malaysia, Selangor 43400, Malaysia; (I.I.M.); (S.L.K.); (U.M.)
| | - Sze Ling Kong
- Laboratory of Plantation Science and Technology, Institute of Plantation Studies, Universiti Putra Malaysia, Selangor 43400, Malaysia; (I.I.M.); (S.L.K.); (U.M.)
| | - Siti Nor Akmar Abdullah
- Laboratory of Plantation Science and Technology, Institute of Plantation Studies, Universiti Putra Malaysia, Selangor 43400, Malaysia; (I.I.M.); (S.L.K.); (U.M.)
- Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, Selangor 43400, Malaysia
| | - Umaiyal Munusamy
- Laboratory of Plantation Science and Technology, Institute of Plantation Studies, Universiti Putra Malaysia, Selangor 43400, Malaysia; (I.I.M.); (S.L.K.); (U.M.)
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174
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Leonard S, Meyer S, Lacour S, Nasser W, Hommais F, Reverchon S. APERO: a genome-wide approach for identifying bacterial small RNAs from RNA-Seq data. Nucleic Acids Res 2019; 47:e88. [PMID: 31147705 PMCID: PMC6735904 DOI: 10.1093/nar/gkz485] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 05/06/2019] [Accepted: 05/20/2019] [Indexed: 12/02/2022] Open
Abstract
Small non-coding RNAs (sRNAs) regulate numerous cellular processes in all domains of life. Several approaches have been developed to identify them from RNA-seq data, which are efficient for eukaryotic sRNAs but remain inaccurate for the longer and highly structured bacterial sRNAs. We present APERO, a new algorithm to detect small transcripts from paired-end bacterial RNA-seq data. In contrast to previous approaches that start from the read coverage distribution, APERO analyzes boundaries of individual sequenced fragments to infer the 5′ and 3′ ends of all transcripts. Since sRNAs are about the same size as individual fragments (50–350 nucleotides), this algorithm provides a significantly higher accuracy and robustness, e.g., with respect to spontaneous internal breaking sites. To demonstrate this improvement, we develop a comparative assessment on datasets from Escherichia coli and Salmonella enterica, based on experimentally validated sRNAs. We also identify the small transcript repertoire of Dickeya dadantii including putative intergenic RNAs, 5′ UTR or 3′ UTR-derived RNA products and antisense RNAs. Comparisons to annotations as well as RACE-PCR experimental data confirm the precision of the detected transcripts. Altogether, APERO outperforms all existing methods in terms of sRNA detection and boundary precision, which is crucial for comprehensive genome annotations. It is freely available as an open source R package on https://github.com/Simon-Leonard/APERO
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Affiliation(s)
- Simon Leonard
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Sam Meyer
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Stephan Lacour
- Univ. Grenoble Alpes, CNRS, Inria, LiPhy (UMR5588), 38000 Grenoble, France
| | - William Nasser
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Florence Hommais
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
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175
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Jiang L, Wang P, Li X, Lv R, Wang L, Yang B, Huang D, Feng L, Liu B. PagR mediates the precise regulation of
Salmonella
pathogenicity island 2 gene expression in response to magnesium and phosphate signals in
Salmonella
Typhimurium. Cell Microbiol 2019; 22:e13125. [DOI: 10.1111/cmi.13125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 01/04/2023]
Affiliation(s)
- Lingyan Jiang
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
- Tianjin Key Laboratory of Microbial Functional GenomicsNankai University Tianjin China
| | - Peisheng Wang
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
| | - Xiaomin Li
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
| | - Runxia Lv
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
| | - Lin Wang
- Inspection and Quarantine Technical CenterBeijing Entry‐Exit Inspection and Quarantine Bureau Beijing China
| | - Bin Yang
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
- Tianjin Key Laboratory of Microbial Functional GenomicsNankai University Tianjin China
| | - Di Huang
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
- Tianjin Key Laboratory of Microbial Functional GenomicsNankai University Tianjin China
| | - Lu Feng
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
- Tianjin Key Laboratory of Microbial Functional GenomicsNankai University Tianjin China
| | - Bin Liu
- TEDA Institute of Biological Sciences and BiotechnologyNankai University Tianjin China
- The Key Laboratory of Molecular Microbiology and TechnologyMinistry of Education Tianjin China
- Tianjin Key Laboratory of Microbial Functional GenomicsNankai University Tianjin China
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176
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Multidrug Resistance Regulators MarA, SoxS, Rob, and RamA Repress Flagellar Gene Expression and Motility in Salmonella enterica Serovar Typhimurium. J Bacteriol 2019; 201:JB.00385-19. [PMID: 31501286 DOI: 10.1128/jb.00385-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 09/03/2019] [Indexed: 12/21/2022] Open
Abstract
Production of flagella is costly and subject to global multilayered regulation, which is reflected in the hierarchical control of flagellar production in many bacterial species. For Salmonella enterica serovar Typhimurium and its relatives, global regulation of flagellar production primarily occurs through the control of flhDC transcription and mRNA translation. In this study, the roles of the homologous multidrug resistance regulators MarA, SoxS, Rob, and RamA (constituting the mar-sox-rob regulon in S Typhimurium) in regulating flagellar gene expression were explored. Each of these regulators was found to inhibit flagellar gene expression, production of flagella, and motility. To different degrees, repression via these transcription factors occurred through direct interactions with the flhDC promoter, particularly for MarA and Rob. Additionally, SoxS repressed flagellar gene expression via a posttranscriptional pathway, reducing flhDC translation. The roles of these transcription factors in reducing motility in the presence of salicylic acid were also elucidated, adding a genetic regulatory element to the response of S Typhimurium to this well-characterized chemorepellent. Integration of flagellar gene expression into the mar-sox-rob regulon in S Typhimurium contrasts with findings for closely related species such as Escherichia coli, providing an example of plasticity in the mar-sox-rob regulon throughout the Enterobacteriaceae family.IMPORTANCE The mar-sox-rob regulon is a large and highly conserved stress response network in the Enterobacteriaceae family. Although it is well characterized in E. coli, the extent of this regulon in related species is unclear. Here, the control of costly flagellar gene expression is connected to the mar-sox-rob regulon of S Typhimurium, contrasting with the E. coli regulon model. These findings demonstrate the flexibility of the mar-sox-rob regulon to accommodate novel regulatory targets, and they provide evidence for its broader regulatory role within this family of diverse bacteria.
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177
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Canals R, Chaudhuri RR, Steiner RE, Owen SV, Quinones-Olvera N, Gordon MA, Baym M, Ibba M, Hinton JCD. The fitness landscape of the African Salmonella Typhimurium ST313 strain D23580 reveals unique properties of the pBT1 plasmid. PLoS Pathog 2019; 15:e1007948. [PMID: 31560731 PMCID: PMC6785131 DOI: 10.1371/journal.ppat.1007948] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 10/09/2019] [Accepted: 08/30/2019] [Indexed: 12/13/2022] Open
Abstract
We have used a transposon insertion sequencing (TIS) approach to establish the fitness landscape of the African Salmonella enterica serovar Typhimurium ST313 strain D23580, to complement our previous comparative genomic and functional transcriptomic studies. We used a genome-wide transposon library with insertions every 10 nucleotides to identify genes required for survival and growth in vitro and during infection of murine macrophages. The analysis revealed genomic regions important for fitness under two in vitro growth conditions. Overall, 724 coding genes were required for optimal growth in LB medium, and 851 coding genes were required for growth in SPI-2-inducing minimal medium. These findings were consistent with the essentiality analyses of other S. Typhimurium ST19 and S. Typhi strains. The global mutagenesis approach also identified 60 sRNAs and 413 intergenic regions required for growth in at least one in vitro growth condition. By infecting murine macrophages with the transposon library, we identified 68 genes that were required for intra-macrophage replication but did not impact fitness in vitro. None of these genes were unique to S. Typhimurium D23580, consistent with a high conservation of gene function between S. Typhimurium ST313 and ST19 and suggesting that novel virulence factors are not involved in the interaction of strain D23580 with murine macrophages. We discovered that transposon insertions rarely occurred in many pBT1 plasmid-encoded genes (36), compared with genes carried by the pSLT-BT virulence plasmid and other bacterial plasmids. The key essential protein encoded by pBT1 is a cysteinyl-tRNA synthetase, and our enzymological analysis revealed that the plasmid-encoded CysRSpBT1 had a lower ability to charge tRNA than the chromosomally-encoded CysRSchr enzyme. The presence of aminoacyl-tRNA synthetases in plasmids from a range of Gram-negative and Gram-positive bacteria suggests that plasmid-encoded essential genes are more common than had been appreciated.
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Affiliation(s)
- Rocío Canals
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Roy R Chaudhuri
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Rebecca E Steiner
- Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Siân V Owen
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Natalia Quinones-Olvera
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Melita A Gordon
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom.,Malawi-Liverpool-Wellcome Trust Clinical Research Programme, University of Malawi College of Medicine, Blantyre, Malawi, Central Africa
| | - Michael Baym
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael Ibba
- Department of Microbiology, The Ohio State University, Columbus, Ohio, United States of America.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Jay C D Hinton
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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178
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Hu W, Chan H, Lu L, Wong KT, Wong SH, Li MX, Xiao ZG, Cho CH, Gin T, Chan MTV, Wu WKK, Zhang L. Autophagy in intracellular bacterial infection. Semin Cell Dev Biol 2019; 101:41-50. [PMID: 31408699 DOI: 10.1016/j.semcdb.2019.07.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/06/2019] [Accepted: 07/30/2019] [Indexed: 12/11/2022]
Abstract
Autophagy is a conserved intracellular degradation process enclosing the bulk of cytosolic components for lysosomal degradation to maintain cellular homeostasis. Accumulating evidences showed that a specialized form of autophagy, known as xenophagy, could serve as an innate immune response to defend against pathogens invading inside the host cells. Correspondingly, infectious pathogens have developed a variety of strategies to disarm xenophagy, leading to a prolonged and persistent intracellular colonization. In this review, we first summarize the current knowledge about the general mechanisms of intracellular bacterial infections and xenophagy. We then focus on the ongoing battle between these two processes.
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Affiliation(s)
- Wei Hu
- Department of Gastroenterology, Shenzhen Hospital, Southern Medical University, Shenzhen, Guangdong, PR China; Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China
| | - Hung Chan
- Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China
| | - Lan Lu
- Sichuan Industrial Institute of Antibiotics, Chengdu University, Chengdu, Sichuan, PR China
| | - Kam Tak Wong
- Department of Microbiology, The Chinese University of Hong Kong, Hong Kong, China
| | - Sunny H Wong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Digestive Diseases, Li Ka Shing Institute of Health Sciences, and Centre for Gut Microbiota Research, The Chinese University of Hong Kong, Hong Kong, China
| | - Ming X Li
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Zhan G Xiao
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Chi H Cho
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Tony Gin
- Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China
| | - Matthew T V Chan
- Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
| | - William K K Wu
- Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Digestive Diseases, Li Ka Shing Institute of Health Sciences, and Centre for Gut Microbiota Research, The Chinese University of Hong Kong, Hong Kong, China.
| | - Lin Zhang
- Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Digestive Diseases, Li Ka Shing Institute of Health Sciences, and Centre for Gut Microbiota Research, The Chinese University of Hong Kong, Hong Kong, China.
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179
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The Small RNA PinT Contributes to PhoP-Mediated Regulation of the Salmonella Pathogenicity Island 1 Type III Secretion System in Salmonella enterica Serovar Typhimurium. J Bacteriol 2019; 201:JB.00312-19. [PMID: 31262841 DOI: 10.1128/jb.00312-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 06/26/2019] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhimurium induces inflammatory diarrhea and bacterial uptake into intestinal epithelial cells using the Salmonella pathogenicity island 1 (SPI1) type III secretion system (T3SS). HilA activates transcription of the SPI1 structural components and effector proteins. Expression of hilA is activated by HilD, HilC, and RtsA, which act in a complex feed-forward regulatory loop. Many environmental signals and other regulators are integrated into this regulatory loop, primarily via HilD. After the invasion of Salmonella into host intestinal epithelial cells or during systemic replication in macrophages, the SPI T3SS is no longer required or expressed. We have shown that the two-component regulatory system PhoPQ, required for intracellular survival, represses the SPI1 T3SS mostly by controlling the transcription of hilA and hilD Here we show that PinT, one of the PhoPQ-regulated small RNAs (sRNAs), contributes to this regulation by repressing hilA and rtsA translation. PinT base pairs with both the hilA and rtsA mRNAs, resulting in translational inhibition of hilA, but also induces degradation of the rts transcript. PinT also indirectly represses expression of FliZ, a posttranslational regulator of HilD, and directly represses translation of ssrB, encoding the primary regulator of the SPI2 T3SS. Our in vivo mouse competition assays support the concept that PinT controls a series of virulence genes at the posttranscriptional level in order to adapt Salmonella from the invasion stage to intracellular survival.IMPORTANCE Salmonella is one of the most important food-borne pathogens, infecting over one million people in the United States every year. These bacteria use a needle-like device to interact with intestinal epithelial cells, leading to invasion of the cells and induction of inflammatory diarrhea. A complex regulatory network controls expression of the invasion system in response to numerous environmental signals. Here we explore the molecular mechanisms by which the small RNA PinT contributes to this regulation, facilitating inactivation of the system after invasion. PinT controls several important virulence systems in Salmonella, tuning the transition between different stages of infection.
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180
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Miyakoshi M, Matera G, Maki K, Sone Y, Vogel J. Functional expansion of a TCA cycle operon mRNA by a 3' end-derived small RNA. Nucleic Acids Res 2019; 47:2075-2088. [PMID: 30541135 PMCID: PMC6393394 DOI: 10.1093/nar/gky1243] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/13/2018] [Accepted: 12/01/2018] [Indexed: 01/24/2023] Open
Abstract
Global RNA profiling studies in bacteria have predicted the existence of many of small noncoding RNAs (sRNAs) that are processed off mRNA 3′ ends to regulate other mRNAs via the RNA chaperones Hfq and ProQ. Here, we present targets of SdhX (RybD), an Hfq-dependent sRNA that is generated by RNase E mediated 3′ processing of the ∼10 000-nt mRNA of the TCA cycle operon sdhCDAB-sucABCD in enteric bacteria. An in silico search predicted ackA mRNA, which encodes acetate kinase, as a conserved primary target of SdhX. Through base pairing, SdhX represses AckA synthesis during growth of Salmonella on acetate. Repression can be achieved by a naturally occurring 38-nucleotide SdhX variant, revealing the shortest functional Hfq-associated sRNA yet. Salmonella SdhX also targets the mRNAs of fumB (anaerobic fumarase) and yfbV, a gene of unknown function adjacent to ackA. Instead, through a slightly different seed sequence, SdhX can repress other targets in Escherichia coli, namely katG (catalase) and fdoG (aerobic formate dehydrogenase). This study illustrates how a key operon from central metabolism is functionally connected to other metabolic pathways through a 3′ appended sRNA, and supports the notion that mRNA 3′UTRs are a playground for the evolution of regulatory RNA networks in bacteria.
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Affiliation(s)
- Masatoshi Miyakoshi
- Department of Infection Biology, Faculty of Medicine, University of Tsukuba, 305-8575 Tsukuba, Japan.,Department of Biotechnology, Akita Prefectural University, 010-0195 Akita, Japan.,Center for Food Science and Wellness, Gunma University, 371-8510 Maebashi, Japan.,RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany
| | - Gianluca Matera
- RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany
| | - Kanako Maki
- Department of Biotechnology, Akita Prefectural University, 010-0195 Akita, Japan
| | - Yasuhiro Sone
- Department of Biotechnology, Akita Prefectural University, 010-0195 Akita, Japan
| | - Jörg Vogel
- RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, D-97080 Würzburg, Germany.,Helmholtz Institute for RNA-based Infection Research, D-97080 Würzburg, Germany
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181
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Chiok KLR, Shah DH. Identification of common highly expressed genes of Salmonella Enteritidis by in silico prediction of gene expression and in vitro transcriptomic analysis. Poult Sci 2019; 98:2948-2963. [PMID: 30953073 DOI: 10.3382/ps/pez119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/27/2019] [Indexed: 01/02/2023] Open
Abstract
Chickens are the reservoir host of Salmonella Enteritidis. Salmonella Enteritidis colonizes the gastro-intestinal tract of chickens and replicates within macrophages without causing clinically discernable illness. Persistence of S. Enteritidis in the hostile environments of intestinal tract and macrophages allows it to disseminate extra-intestinally to liver, spleen, and reproductive tract. Extra-intestinal dissemination into reproductive tract leads to contamination of internal contents of eggs, which is a major risk factor for human infection. Understanding the genes that contribute to S. Enteritidis persistence in the chicken host is central to elucidate the genetic basis of the unique pathobiology of this public health pathogen. The aim of this study was to identify a succinct set of genes associated with infection-relevant in vitro environments to provide a rational foundation for subsequent biologically-relevant research. We used in silico prediction of gene expression and RNA-seq technology to identify a core set of 73 S. Enteritidis genes that are consistently highly expressed in multiple S. Enteritidis strains cultured at avian physiologic temperature under conditions that represent intestinal and intracellular environments. These common highly expressed (CHX) genes encode proteins involved in bacterial metabolism, protein synthesis, cell-envelope biogenesis, stress response, and a few proteins with uncharacterized functions. Further studies are needed to dissect the contribution of these CHX genes to the pathobiology of S. Enteritidis in the avian host. Several of the CHX genes could serve as promising targets for studies towards the development of immunoprophylactic and novel therapeutic strategies to prevent colonization of chickens and their environment with S. Enteritidis.
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Affiliation(s)
- Kim Lam R Chiok
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040
| | - Devendra H Shah
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040
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182
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Barnhill EC, Crucello A, Houserova D, King VM, Amin SV, Roberts JT, Zambrano ME, DeMeis JD, Dahmer DJ, Ijaz Z, Barchie AA, Watters BC, Prusak JE, Dean MA, Holton NW, Ferreira-Filho JA, Sant'Ana AS, Spector MP, Borchert GM. Characterization of novel small RNAs (sRNAs) contributing to the desiccation response of Salmonella enterica serovar Typhimurium. RNA Biol 2019; 16:1643-1657. [PMID: 31390935 DOI: 10.1080/15476286.2019.1653680] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Noncoding RNA (ncRNA) modulation of gene expression has now been ubiquitously observed across all domains of life. An increasingly apparent role of ncRNAs is to coordinate changes in gene expressions in response to environmental stress. Salmonella enterica, a common food-born pathogen, is known for its striking ability to survive, adapt, and thrive in various unfavourable environments which makes it a particularly difficult pathogen to eliminate as well as an interesting model in which to study ncRNA contributions to cellular stress response. Mounting evidence now suggests that small RNAs (sRNAs) represent key regulators of Salmonella stress adaptation. Approximately 50-500 nucleotides in length, sRNAs regulate gene expression through complementary base pairing with molecular targets and have recently been suggested to outnumber protein-coding genes in bacteria. In this work, we employ small RNA transcriptome sequencing to characterize changes in the sRNA profiles of Salmonella in response to desiccation. In all, we identify 102 previously annotated sRNAs significantly differentially expressed during desiccation; and excitingly, 71 novel sRNAs likewise differentially expressed. Small transcript northern blotting and qRT-PCRs confirm the identities and expressions of several of our novel sRNAs, and computational analyses indicate the majority are highly conserved and structurally related to characterized sRNAs. Predicted sRNA targets include several proteins necessary for desiccation survival and this, in part, suggests a role for desiccation-regulated sRNAs in this stress response. Furthermore, we find individual knock-outs of two of the novel sRNAs identified herein, either sRNA1320429 or sRNA3981754, significantly impairs the ability of Salmonella to survive desiccation, confirming their involvements (and suggesting the potential involvements of other sRNAs we identify in this work) in the Salmonella response to desiccation.
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Affiliation(s)
| | - Aline Crucello
- Department of Biology, University of South Alabama , Mobile , AL , USA.,Department of Food Science, University of Campinas , Campinas , Brazil
| | | | - Valeria M King
- Department of Biology, University of South Alabama , Mobile , AL , USA.,Department of Molecular and Cell Biology, University of California Berkeley , Berkeley , CA , USA
| | - Shivam V Amin
- Department of Biology, University of South Alabama , Mobile , AL , USA.,Department of Pharmacology, USA College of Medicine , Mobile , AL , USA
| | - Justin T Roberts
- Department of Biology, University of South Alabama , Mobile , AL , USA.,Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine , Aurora , CO , USA
| | | | - Jeffrey D DeMeis
- Department of Biology, University of South Alabama , Mobile , AL , USA
| | - Donavon J Dahmer
- Department of Biomedical Sciences, University of South Alabama , Mobile , AL , USA
| | - Zara Ijaz
- Department of Biomedical Sciences, University of South Alabama , Mobile , AL , USA
| | - Addison A Barchie
- Department of Biology, University of South Alabama , Mobile , AL , USA
| | - Brianna C Watters
- Department of Biology, University of South Alabama , Mobile , AL , USA
| | - James E Prusak
- Department of Biology, University of South Alabama , Mobile , AL , USA
| | - Meghan A Dean
- Department of Biology, University of South Alabama , Mobile , AL , USA
| | | | - Jaire A Ferreira-Filho
- Center for Molecular Biology and Genetic Engineering, University of Campinas , Campinas , Brazil
| | | | - Michael P Spector
- Department of Biomedical Sciences, University of South Alabama , Mobile , AL , USA
| | - Glen M Borchert
- Department of Biology, University of South Alabama , Mobile , AL , USA.,Department of Pharmacology, USA College of Medicine , Mobile , AL , USA
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183
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Hews CL, Pritchard EJ, Rowley G. The Salmonella Specific, σ E-Regulated, STM1250 and AgsA, Function With the sHsps IbpA and IbpB, to Counter Oxidative Stress and Survive Macrophage Killing. Front Cell Infect Microbiol 2019; 9:263. [PMID: 31396489 PMCID: PMC6663981 DOI: 10.3389/fcimb.2019.00263] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 07/04/2019] [Indexed: 11/13/2022] Open
Abstract
The host presents an array of environments which induce bacterial stress including changes in pH, antimicrobial compounds and reactive oxygen species. The bacterial envelope sits at the interface between the intracellular and extracellular environment and its maintenance is essential for Salmonella cell viability under a range of conditions, including during infection. In this study, we aimed to understand the contribution of the σH- and σE-regulated small heat shock proteins IbpA, IbpB, and AgsA and the putative σE-regulated stress response protein STM1250 to the Salmonella envelope stress response. Due to shared sequence identity, regulatory overlap, and the specificity of STM1250 and AgsA to Salmonella sp., we hypothesized that functional overlap exists between these four stress response proteins, which might afford a selective advantage during Salmonella exposure to stress. We present here new roles for three small heat shock proteins and a putative stress response protein in Salmonella that are not limited to heat shock. We have shown that, compared to WT, a quadruple mutant is significantly more sensitive to hydrogen peroxide, has a lower minimum bactericidal concentration to the cationic antimicrobial peptide polymyxin B, and is attenuated in macrophages.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Emily J Pritchard
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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184
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Hurst TP, Aswad A, Karamitros T, Katzourakis A, Smith AL, Magiorkinis G. Interferon-Inducible Protein 16 (IFI16) Has a Broad-Spectrum Binding Ability Against ssDNA Targets: An Evolutionary Hypothesis for Antiretroviral Checkpoint. Front Microbiol 2019; 10:1426. [PMID: 31333597 PMCID: PMC6621918 DOI: 10.3389/fmicb.2019.01426] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 06/05/2019] [Indexed: 12/14/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are under genomic and epigenetic control but can be expressed in normal tissues, producing RNA transcripts some of which are translated. While it has not been demonstrated experimentally in modern humans, cDNA copies from HERV RNA (namely HERV-K HML-2 or HK2) were produced after the human-chimp split and until at least 250,000 years ago. We were interested in determining if such cDNA could be a ligand for pattern recognition receptors (PRRs) of the innate immune response. The AIM-2-like receptors for DNA, interferon-γ-inducible protein 16 (IFI16) and Cyclic GMP-AMP synthase (cGAS) were candidate PRRs. IFI16 can detect cDNA produced during HIV-1 replication, causing increased T cell death. While HIV-1 has emerged relatively recently as a human pathogen, the cDNA functionality of IFI16 could have been selected for during the course of human evolution. Here we present a novel hypothesis that the products of reverse transcription of HK2, which has been proliferating in the genome of human ancestors for 30 million years, could interact with IFI16. In support of our hypothesis, we provide preliminary data showing that IFI16 (but not cGAS) interacts with synthetic single-stranded HK2 oligos corresponding to the first product of reverse transcription. Further, we show that ssDNA detection by IFI16 has variability with respect to sequence features but is not dependent on strong secondary structures mimicking dsDNA. Among the HK2 oligos, IFI16 interacts more intensely with those derived from LTRs, suggesting these oligos have undetermined structural features that allow IFI16 to bind with greater affinity. Further, cells with stem cell features that naturally allow HK2 expression were found to express many components of the innate immune system including cGAS but not IFI16. Based on the presented preliminary data we further postulate another hypothesis: that the IFI16 functionality in human cells has been acting as "second-line" defense to control abnormal HK2 replication in somatic tissues. The absence of this protein in stem cells and a stem cell line could permit these cells to express HERVs which contribute to stem cell identity. Finally, we also comment on potential studies that could support or refute our hypothesis.
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Affiliation(s)
- Tara Patricia Hurst
- Department of Zoology, University of Oxford, Oxford, United Kingdom.,Department of Life Sciences, School of Health Sciences, Birmingham City University, Birmingham, United Kingdom
| | - Amr Aswad
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Timokratis Karamitros
- Department of Zoology, University of Oxford, Oxford, United Kingdom.,Laboratory of Medical Microbiology, Department of Microbiology, Hellenic Pasteur Institute, Athens, Greece
| | - Aris Katzourakis
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Adrian L Smith
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Gkikas Magiorkinis
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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185
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Aprianto R, Slager J, Holsappel S, Veening JW. High-resolution analysis of the pneumococcal transcriptome under a wide range of infection-relevant conditions. Nucleic Acids Res 2019; 46:9990-10006. [PMID: 30165663 PMCID: PMC6212715 DOI: 10.1093/nar/gky750] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/09/2018] [Indexed: 12/18/2022] Open
Abstract
Streptococcus pneumoniae is an opportunistic human pathogen that typically colonizes the nasopharyngeal passage and causes lethal disease in other host niches, such as the lung or the meninges. The expression and regulation of pneumococcal genes at different life-cycle stages, such as commensal or pathogenic, are not entirely understood. To chart the transcriptional responses of S. pneumoniae, we used RNA-seq to quantify the relative abundance of the transcriptome under 22 different infection-relevant conditions. The data demonstrated a high level of dynamic expression and, strikingly, all annotated pneumococcal genomic features were expressed in at least one of the studied conditions. By computing the correlation values of every pair of genes across all studied conditions, we created a co-expression matrix that provides valuable information on both operon structure and regulatory processes. The co-expression data are highly consistent with well-characterized operons and regulons, such as the PyrR, ComE and ComX regulons, and have allowed us to identify a new member of the competence regulon. Lastly, we created an interactive data center named PneumoExpress (https://veeninglab.com/pneumoexpress) that enables users to access the expression data as well as the co-expression matrix in an intuitive and efficient manner, providing a valuable resource to the pneumococcal research community.
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Affiliation(s)
- Rieza Aprianto
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jelle Slager
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Siger Holsappel
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.,Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
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186
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Structural and Functional Variation in Outer Membrane Polysaccharide Export (OPX) Proteins from the Two Major Capsule Assembly Pathways Present in Escherichia coli. J Bacteriol 2019; 201:JB.00213-19. [PMID: 31036729 DOI: 10.1128/jb.00213-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 04/26/2019] [Indexed: 11/20/2022] Open
Abstract
Capsular polysaccharides (CPSs) are virulence factors for many important pathogens. In Escherichia coli, CPSs are synthesized via two distinct pathways, but both require proteins from the outer membrane polysaccharide export (OPX) family to complete CPS export from the periplasm to the cell surface. In this study, we compare the properties of the OPX proteins from the prototypical group 1 (Wzy-dependent) and group 2 (ABC transporter-dependent) pathways in E. coli K30 (Wza) and E. coli K2 (KpsD), respectively. In addition, we compare an OPX from Salmonella enterica serovar Typhi (VexA), which shares structural properties with Wza, while operating in an ABC transporter-dependent pathway. These proteins differ in distribution in the cell envelope and formation of stable multimers, but these properties do not align with acylation or the interfacing biosynthetic pathway. In E. coli K2, murein lipoprotein (Lpp) plays a role in peptidoglycan association of KpsD, and loss of this interaction correlates with impaired group 2 capsule production. VexA also depends on Lpp for peptidoglycan association, but CPS production is unaffected in an lpp mutant. In contrast, Wza and group 1 capsule production is unaffected by the absence of Lpp. These results point to complex structure-function relationships between different OPX proteins.IMPORTANCE Capsules are protective layers of polysaccharides that surround the cell surface of many bacteria, including that of Escherichia coli isolates and Salmonella enterica serovar Typhi. Capsular polysaccharides (CPSs) are often essential for virulence because they facilitate evasion of host immune responses. The attenuation of unencapsulated mutants in animal models and the involvement of protein families with conserved features make the CPS export pathway a novel candidate for therapeutic strategies. However, appropriate "antivirulence" strategies require a fundamental understanding of the underpinning cellular processes. Investigating export proteins that are conserved across different biosynthesis strategies will give important insight into how CPS is transported to the cell surface.
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187
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Gottesman S. Trouble is coming: Signaling pathways that regulate general stress responses in bacteria. J Biol Chem 2019; 294:11685-11700. [PMID: 31197038 DOI: 10.1074/jbc.rev119.005593] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Bacteria can rapidly and reversibly respond to changing environments via complex transcriptional and post-transcriptional regulatory mechanisms. Many of these adaptations are specific, with the regulatory output tailored to the inducing signal (for instance, repairing damage to cell components or improving acquisition and use of growth-limiting nutrients). However, the general stress response, activated in bacterial cells entering stationary phase or subjected to nutrient depletion or cellular damage, is unique in that its common, broad output is induced in response to many different signals. In many different bacteria, the key regulator for the general stress response is a specialized sigma factor, the promoter specificity subunit of RNA polymerase. The availability or activity of the sigma factor is regulated by complex regulatory circuits, the majority of which are post-transcriptional. In Escherichia coli, multiple small regulatory RNAs, each made in response to a different signal, positively regulate translation of the general stress response sigma factor RpoS. Stability of RpoS is regulated by multiple anti-adaptor proteins that are also synthesized in response to different signals. In this review, the modes of signaling to and levels of regulation of the E. coli general stress response are discussed. They are also used as a basis for comparison with the general stress response in other bacteria with the aim of extracting key principles that are common among different species and highlighting important unanswered questions.
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Affiliation(s)
- Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
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188
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Khajanchi BK, Xu J, Grim CJ, Ottesen AR, Ramachandran P, Foley SL. Global transcriptomic analyses of Salmonella enterica in Iron-depleted and Iron-rich growth conditions. BMC Genomics 2019; 20:490. [PMID: 31195964 PMCID: PMC6567447 DOI: 10.1186/s12864-019-5768-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 05/03/2019] [Indexed: 02/06/2023] Open
Abstract
Background Salmonella enterica possess several iron acquisition systems, encoded on the chromosome and plasmids. Recently, we demonstrated that incompatibility group (Inc) FIB plasmid-encoded iron acquisition systems (Sit and aerobactin) likely play an important role in persistence of Salmonella in human intestinal epithelial cells (Caco-2). In this study, we sought to determine global transcriptome analyses of S. enterica in iron-rich (IR) and iron-depleted (ID) growth conditions. Results The number of differentially-expressed genes were substantially higher for recipient (SE819) (n = 966) and transconjugant (TC) (n = 945) compared to the wild type (WT) (SE163A) (n = 110) strain in ID as compared to IR growth conditions. Several virulence-associated factors including T3SS, flagellin, cold-shock protein (cspE), and regulatory genes were upregulated in TC in ID compared to IR conditions. Whereas, IS1 and acrR/tetR transposases located on the IncFIB plasmid, ferritin and several regulatory genes were downregulated in TC in ID conditions. Enterobactin transporter (entS), iron ABC transporter (fepCD), colicin transporter, IncFIB-encoded enolase, cyclic di-GMP regulator (cdgR) and other regulatory genes of the WT strain were upregulated in ID compared to IR conditions. Conversely, ferritin, ferrous iron transport protein A (feoA), IncFIB-encoded IS1 and acrR/tetR transposases and ArtA toxin of WT were downregulated in ID conditions. SDS-PAGE coupled with LC-MS/MS analyses revealed that siderophore receptor proteins such as chromosomally-encoded IroN and, IncFIB-encoded IutA were upregulated in WT and TC in ID growth conditions. Both chromosome and IncFIB plasmid-encoded SitA was overexpressed in WT, but not in TC or recipient in ID conditions. Increased expression of flagellin was detected in recipient and TC, but not in WT in ID conditions. Conclusion Iron concentrations in growth media influenced differential gene expressions both at transcriptional and translational levels, including genes encoded on the IncFIB plasmid. Limited iron availability within the host may promote pathogenic Salmonella to differentially express subsets of genes encoded by chromosome and/or plasmids, facilitating establishment of successful infection. Electronic supplementary material The online version of this article (10.1186/s12864-019-5768-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bijay K Khajanchi
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA.
| | - Joshua Xu
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA
| | - Christopher J Grim
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, Laurel, MD, USA
| | - Andrea R Ottesen
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, College Park, MD, USA
| | - Padmini Ramachandran
- Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, College Park, MD, USA
| | - Steven L Foley
- National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA.
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189
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The Interplay between Salmonella enterica Serovar Typhimurium and the Intestinal Mucosa during Oral Infection. Microbiol Spectr 2019; 7. [PMID: 30953432 DOI: 10.1128/microbiolspec.bai-0004-2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Bacterial infection results in a dynamic interplay between the pathogen and its host. The underlying interactions are multilayered, and the cellular responses are modulated by the local environment. The intestine is a particularly interesting tissue regarding host-pathogen interaction. It is densely colonized by commensal microbes and a portal of entry for ingested pathogens. This necessitates constant monitoring of microbial stimuli in order to maintain homeostasis during encounters with benign microbiota and to trigger immune defenses in response to bacterial pathogens. Homeostasis is maintained by physical barriers (the mucus layer and epithelium), chemical defenses (antimicrobial peptides), and innate immune responses (NLRC4 inflammasome), which keep the bacteria from reaching the sterile lamina propria. Intestinal pathogens represent potent experimental tools to probe these barriers and decipher how pathogens can circumvent them. The streptomycin mouse model of oral Salmonella enterica serovar Typhimurium infection provides a well-characterized, robust experimental system for such studies. Strikingly, each stage of the gut tissue infection poses a different set of challenges to the pathogen and requires tight control of virulence factor expression, host response modulation, and cooperation between phenotypic subpopulations. Therefore, successful infection of the intestinal tissue relies on a delicate and dynamic balance between responses of the pathogen and its host. These mechanisms can be deciphered to their full extent only in realistic in vivo infection models.
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190
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Comparative Transcriptomic Profiling of Yersinia enterocolitica O:3 and O:8 Reveals Major Expression Differences of Fitness- and Virulence-Relevant Genes Indicating Ecological Separation. mSystems 2019; 4:mSystems00239-18. [PMID: 31020044 PMCID: PMC6478967 DOI: 10.1128/msystems.00239-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 02/27/2019] [Indexed: 01/16/2023] Open
Abstract
Yersinia enterocolitica is a major diarrheal pathogen and is associated with a large range of gut-associated diseases. Members of this species have evolved into different phylogroups with genotypic variations. We performed the first characterization of the Y. enterocolitica transcriptional landscape and tracked the consequences of the genomic variations between two different pathogenic phylogroups by comparing their RNA repertoire, promoter usage, and expression profiles under four different virulence-relevant conditions. Our analysis revealed major differences in the transcriptional outputs of the closely related strains, pointing to an ecological separation in which one is more adapted to an environmental lifestyle and the other to a mostly mammal-associated lifestyle. Moreover, a variety of pathoadaptive alterations, including alterations in acid resistance genes, colonization factors, and toxins, were identified which affect virulence and host specificity. This illustrates that comparative transcriptomics is an excellent approach to discover differences in the functional output from closely related genomes affecting niche adaptation and virulence, which cannot be directly inferred from DNA sequences. Yersinia enterocolitica is a zoonotic pathogen and an important cause of bacterial gastrointestinal infections in humans. Large-scale population genomic analyses revealed genetic and phenotypic diversity of this bacterial species, but little is known about the differences in the transcriptome organization, small RNA (sRNA) repertoire, and transcriptional output. Here, we present the first comparative high-resolution transcriptome analysis of Y. enterocolitica strains representing highly pathogenic phylogroup 2 (serotype O:8) and moderately pathogenic phylogroup 3 (serotype O:3) grown under four infection-relevant conditions. Our transcriptome sequencing (RNA-seq) approach revealed 1,299 and 1,076 transcriptional start sites and identified strain-specific sRNAs that could contribute to differential regulation among the phylogroups. Comparative transcriptomics further uncovered major gene expression differences, in particular, in the temperature-responsive regulon. Multiple virulence-relevant genes are differentially regulated between the two strains, supporting an ecological separation of phylogroups with certain niche-adapted properties. Strong upregulation of the ystA enterotoxin gene in combination with constitutive high expression of cell invasion factor InvA further showed that the toxicity of recent outbreak O:3 strains has increased. Overall, our report provides new insights into the specific transcriptome organization of phylogroups 2 and 3 and reveals gene expression differences contributing to the substantial phenotypic differences that exist between the lineages. IMPORTANCEYersinia enterocolitica is a major diarrheal pathogen and is associated with a large range of gut-associated diseases. Members of this species have evolved into different phylogroups with genotypic variations. We performed the first characterization of the Y. enterocolitica transcriptional landscape and tracked the consequences of the genomic variations between two different pathogenic phylogroups by comparing their RNA repertoire, promoter usage, and expression profiles under four different virulence-relevant conditions. Our analysis revealed major differences in the transcriptional outputs of the closely related strains, pointing to an ecological separation in which one is more adapted to an environmental lifestyle and the other to a mostly mammal-associated lifestyle. Moreover, a variety of pathoadaptive alterations, including alterations in acid resistance genes, colonization factors, and toxins, were identified which affect virulence and host specificity. This illustrates that comparative transcriptomics is an excellent approach to discover differences in the functional output from closely related genomes affecting niche adaptation and virulence, which cannot be directly inferred from DNA sequences.
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191
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Ray S, Da Costa R, Das M, Nandi D. Interplay of cold shock protein E with an uncharacterized protein, YciF, lowers porin expression and enhances bile resistance in Salmonella Typhimurium. J Biol Chem 2019; 294:9084-9099. [PMID: 30992363 DOI: 10.1074/jbc.ra119.008209] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/07/2019] [Indexed: 11/06/2022] Open
Abstract
Bacterial cold shock proteins (CSPs) function as RNA chaperones. To assess CSP's roles in the intracellular human pathogen Salmonella Typhimurium, we analyzed their expression in varied stress conditions. We found that cold shock protein E (cspE or STM14_0732) is up-regulated during bile salt-induced stress and that an S. Typhimurium strain lacking cspE (ΔcspE) displays dose-dependent sensitivity to bile salts, specifically to deoxycholate. We also found that an uncharacterized gene, yciF (STM14_2092), is up-regulated in response to bile stress in WT but not in the ΔcspE strain. Complementation with WT CspE, but not with a F30V CspE variant, abrogated the bile sensitivity of ΔcspE as did multicopy overexpression of yciF. Northern blotting experiments with rifampicin disclosed that the regulation of yciF expression is, most likely, due to the RNA-stabilizing activity of CspE. Importantly, electrophoretic mobility shift assays indicated that purified CspE, but not the F30V variant, directly binds yciF mRNA. We also observed that the extra-cytoplasmic stress-response (ESR) pathway is augmented in the bile-treated ΔcspE strain, as judged by induction of RpoE regulon genes (rpoE, degP, and rybB) and downstream ESR genes (hfq, rne, and PNPase). Moreover, the transcript levels of the porin genes, ompD, ompF, and ompC, were higher in bile salts-stressed ΔcspE and correlated with higher intracellular accumulation of the fluorescent DNA stain bisBenzimide H 33258, indicating greater cell permeability. In conclusion, our study has identified YciF, a CspE target involved in the regulation of porins and in countering bile stress in S. Typhimurium.
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Affiliation(s)
| | | | | | - Dipankar Nandi
- From the Department of Biochemistry, .,Center for Infectious Diseases Research, Indian Institute of Science, Bangalore-560012, India
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192
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Salmonella Proteomic Profiling during Infection Distinguishes the Intracellular Environment of Host Cells. mSystems 2019; 4:mSystems00314-18. [PMID: 30984873 PMCID: PMC6456673 DOI: 10.1128/msystems.00314-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/14/2019] [Indexed: 02/06/2023] Open
Abstract
Salmonella Typhimurium is one of the leading causes of foodborne bacterial infection. Nevertheless, how Salmonella adapts to distinct types of host cells during infection remains poorly understood. By contrasting intracellular Salmonella proteomes from both infected macrophages and epithelial cells, we found striking proteomic signatures specific to particular types of host cells. Notably, Salmonella proteomic remodeling exhibited quicker kinetics in macrophages than in epithelial cells with respect to bacterial virulence and flagellar and chemotaxis systems. Furthermore, we unveiled high levels of induction of bacterial histidine biosynthesis in macrophages but not in epithelial cells, which is attributable to differing intracellular levels of this amino acid. Intriguingly, we found that a defective hisG gene renders a Salmonella strain hypersensitive to histidine shortage in macrophages. Overall, our work reveals specific Salmonella adaptation mechanisms in distinct host cells, which should aid in the development of novel anti-infection strategies. Essential to bacterial pathogenesis, Salmonella enterica serovar Typhimurium (S. Typhimurium) has evolved the capacity to quickly sense and adapt to specific intracellular environment within distinct host cells. Here we examined S. Typhimurium proteomic remodeling within macrophages, allowing direct comparison with our previous studies in epithelial cells. In addition to many shared features, our data revealed proteomic signatures highly specific to one type of host cells. Notably, intracellular S. Typhimurium differentially regulates the two type III secretion systems (T3SSs) far more quickly in macrophages than in epithelial cells; bacterial flagellar and chemotaxis systems degenerate more quickly in macrophages than in HeLa cells as well. Importantly, our comparative analysis uncovered high levels of induction of bacterial histidine biosynthesis in macrophages but not in epithelial cells. Targeted metabolomic measurements revealed markedly lower histidine levels within macrophages. Intriguingly, further functional studies established that histidine biosynthesis that is defective (due to a hisG mutation) renders the bacterium (strain SL1344) hypersensitive to intracellular shortage of this amino acid. Indeed, another S. Typhimurium strain, namely, strain 14028s, with a fully functional biosynthetic pathway exhibited only minor induction of the his operon within infected macrophages. Our work thus provided novel insights into S. Typhimurium adaptation mechanisms within distinct host cells and also provided an elegant paradigm where proteomic profiling of intracellular pathogens is utilized to discriminate specific host environments (e.g., on the basis of nutrient availability). IMPORTANCESalmonella Typhimurium is one of the leading causes of foodborne bacterial infection. Nevertheless, how Salmonella adapts to distinct types of host cells during infection remains poorly understood. By contrasting intracellular Salmonella proteomes from both infected macrophages and epithelial cells, we found striking proteomic signatures specific to particular types of host cells. Notably, Salmonella proteomic remodeling exhibited quicker kinetics in macrophages than in epithelial cells with respect to bacterial virulence and flagellar and chemotaxis systems. Furthermore, we unveiled high levels of induction of bacterial histidine biosynthesis in macrophages but not in epithelial cells, which is attributable to differing intracellular levels of this amino acid. Intriguingly, we found that a defective hisG gene renders a Salmonella strain hypersensitive to histidine shortage in macrophages. Overall, our work reveals specific Salmonella adaptation mechanisms in distinct host cells, which should aid in the development of novel anti-infection strategies.
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193
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Abstract
Signal transduction systems dictate various cellular behaviors in response to environmental changes. To operate cellular programs appropriately, organisms have sophisticated regulatory factors to optimize the signal response. The PhoP/PhoQ master virulence regulatory system of the intracellular pathogen Salmonella enterica is activated inside acidic macrophage phagosomes. Here we report that Salmonella delays the activation of this system inside macrophages using an inhibitory protein, EIIANtr (a component of the nitrogen-metabolic phosphotransferase system). We establish that EIIANtr directly restrains PhoP binding to its target promoter, thereby negatively controlling the expression of PhoP-activated genes. PhoP furthers its activation by promoting Lon-mediated degradation of EIIANtr at acidic pH. These results suggest that Salmonella ensures robust activation of its virulence system by suspending the activation of PhoP until a sufficient level of active PhoP is present to overcome the inhibitory effect of EIIANtr Our findings reveal how a pathogen precisely and efficiently operates its virulence program during infection.IMPORTANCE To accomplish successful infection, pathogens must operate their virulence programs in a precise, time-sensitive, and coordinated manner. A major question is how pathogens control the timing of virulence gene expression during infection. Here we report that the intracellular pathogen Salmonella controls the timing and level of virulence gene expression by using an inhibitory protein, EIIANtr A DNA binding master virulence regulator, PhoP, controls various virulence genes inside acidic phagosomes. Salmonella decreases EIIANtr amounts at acidic pH in a Lon- and PhoP-dependent manner. This, in turn, promotes expression of the PhoP-activated virulence program because EIIANtr hampers activation of PhoP-regulated genes by interfering with PhoP binding to DNA. EIIANtr enables Salmonella to impede the activation of PhoP-regulated gene expression inside macrophages. Our findings suggest that Salmonella achieves programmed delay of virulence gene activation by adjusting levels of an inhibitory factor.
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194
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Rhen M. Salmonella and Reactive Oxygen Species: A Love-Hate Relationship. J Innate Immun 2019; 11:216-226. [PMID: 30943492 DOI: 10.1159/000496370] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 12/19/2018] [Indexed: 12/22/2022] Open
Abstract
Salmonella enterica represents an enterobacterial species including numerous serovars that cause infections at, or initiated at, the intestinal epithelium. Many serovars also act as facultative intracellular pathogens with a tropism for phagocytic cells. These bacteria not only survive in phagocytes but also undergo de facto replication therein. Phagocytes, through the activities of phagocyte NADPH-dependent oxidase and inducible nitric oxide synthase, are very proficient in converting molecular oxygen to reactive oxygen (ROS) and nitrogen species (RNS). These compounds represent highly efficient effectors of the innate immune defense. Salmonella is by no means resistant to these effectors, which may stand in contrast to the host niches chosen. To cope with this paradox, these bacteria rely on an array of detoxification and repair systems. Combination these systems allows for a high enough tolerance to ROS and RNS to enable establishment of infection. In addition, salmonella possesses protein factors that have the potential to dampen the infection-associated inflammation, which evidently results in a reduced exposure to ROS and RNS. This review attempts to summarize the activities and strategies by which salmonella tries to cope with ROS and RNS and how the bacterium can make use of these innate defense factors.
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Affiliation(s)
- Mikael Rhen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden, .,Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden, .,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden,
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195
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Mutational and non mutational adaptation of Salmonella enterica to the gall bladder. Sci Rep 2019; 9:5203. [PMID: 30914708 PMCID: PMC6435676 DOI: 10.1038/s41598-019-41600-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/12/2019] [Indexed: 02/06/2023] Open
Abstract
During systemic infection of susceptible hosts, Salmonella enterica colonizes the gall bladder, which contains lethal concentrations of bile salts. Recovery of Salmonella cells from the gall bladder of infected mice yields two types of isolates: (i) bile-resistant mutants; (ii) isolates that survive lethal selection without mutation. Bile-resistant mutants are recovered at frequencies high enough to suggest that increased mutation rates may occur in the gall bladder, thus providing a tentative example of stress-induced mutation in a natural environment. However, most bile-resistant mutants characterized in this study show defects in traits that are relevant for Salmonella colonization of the animal host. Mutation may thus permit short-term adaptation to the gall bladder at the expense of losing fitness for transmission to new hosts. In contrast, non mutational adaptation may have evolved as a fitness-preserving strategy. Failure of RpoS− mutants to colonize the gall bladder supports the involvement of the general stress response in non mutational adaptation.
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196
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SlyA and HilD Counteract H-NS-Mediated Repression on the ssrAB Virulence Operon of Salmonella enterica Serovar Typhimurium and Thus Promote Its Activation by OmpR. J Bacteriol 2019; 201:JB.00530-18. [PMID: 30718301 DOI: 10.1128/jb.00530-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 01/26/2019] [Indexed: 02/03/2023] Open
Abstract
H-NS-mediated repression of acquired genes and the subsequent adaptation of regulatory mechanisms that counteract this repression have played a central role in the Salmonella pathogenicity evolution. The Salmonella pathogenicity island 2 (SPI-2) is an acquired chromosomal region containing genes necessary for Salmonella enterica to colonize and replicate in different niches of hosts. The ssrAB operon, located in SPI-2, encodes the two-component system SsrA-SsrB, which positively controls the expression of the SPI-2 genes but also other many genes located outside SPI-2. Several regulators have been involved in the expression of ssrAB, such as the ancestral regulators SlyA and OmpR, and the acquired regulator HilD. In this study, we show how SlyA, HilD, and OmpR coordinate to induce the expression of ssrAB under different growth conditions. We found that when Salmonella enterica serovar Typhimurium is grown in nutrient-rich lysogeny broth (LB), SlyA and HilD additively counteract H-NS-mediated repression on ssrAB, whereas in N-minimal medium (N-MM), SlyA antagonizes H-NS-mediated repression on ssrAB independently of HilD. Interestingly, our results indicate that OmpR is required for the expression of ssrAB independently of the growth conditions, even in the absence of repression by H-NS. Therefore, our data support two mechanisms adapted for the expression of ssrAB under different growth conditions. One involves the additive action of SlyA and HilD, whereas the other involves SlyA, but not HilD, to counteract H-NS-mediated repression on ssrAB, thus favoring in both cases the activation of ssrAB by OmpR.IMPORTANCE The global regulator H-NS represses the expression of acquired genes and thus avoids possible detrimental effects on bacterial fitness. Regulatory mechanisms are adapted to induce expression of the acquired genes in particular niches to obtain a benefit from the information encoded in the foreign DNA, as for pathogenesis. Here, we show two mechanisms that were integrated for the expression of virulence genes in Salmonella Typhimurium. One involves the additive action of the regulators SlyA and HilD, whereas the other involves SlyA, but not HilD, to counteract H-NS-mediated repression on the ssrAB operon, thus favoring its activation by the OmpR regulator. To our knowledge, this is the first report involving the coordinated action of two regulators to counteract H-NS-mediated repression.
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197
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Crucello A, Furtado MM, Chaves MDR, Sant'Ana AS. Transcriptome sequencing reveals genes and adaptation pathways in Salmonella Typhimurium inoculated in four low water activity foods. Food Microbiol 2019; 82:426-435. [PMID: 31027802 DOI: 10.1016/j.fm.2019.03.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/09/2019] [Accepted: 03/14/2019] [Indexed: 11/25/2022]
Abstract
Salmonella enterica serotypes have been reported as the agent of various outbreaks occurred after the consumption of low water activity (aw) foods. When the pathogen encounters harsh conditions, several regulatory networks are activated through dynamic differential gene expression that lead to cell survival for prolonged periods. In this work, the transcriptome of S. enterica serovar Typhimurium using RNA-Seq, after cells' inoculation in four distinct types of low aw foods (milk chocolate, powdered milk, black pepper, and dried pet food), following storage at 25 °C per 24 and 72 h was studied. The findings of this study suggest that gene regulation is influenced by the food composition mainly in the first 24 h post-inoculum, proceeded by the induction of similar genes shared among all samples. It was possible to evaluate the differences on each type of food matrix regarding the bacteria adaptation, as well as the similarities provoked by low aw. The results reveal genes that may play key roles in response to desiccation in Salmonella, as well as the pathways in which they are involved.
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Affiliation(s)
- Aline Crucello
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Marianna M Furtado
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Monyca D R Chaves
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Anderson S Sant'Ana
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil.
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198
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Will WR, Brzovic P, Le Trong I, Stenkamp RE, Lawrenz MB, Karlinsey JE, Navarre WW, Main-Hester K, Miller VL, Libby SJ, Fang FC. The Evolution of SlyA/RovA Transcription Factors from Repressors to Countersilencers in Enterobacteriaceae. mBio 2019; 10:e00009-19. [PMID: 30837332 PMCID: PMC6401476 DOI: 10.1128/mbio.00009-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 01/29/2019] [Indexed: 02/02/2023] Open
Abstract
Gene duplication and subsequent evolutionary divergence have allowed conserved proteins to develop unique roles. The MarR family of transcription factors (TFs) has undergone extensive duplication and diversification in bacteria, where they act as environmentally responsive repressors of genes encoding efflux pumps that confer resistance to xenobiotics, including many antimicrobial agents. We have performed structural, functional, and genetic analyses of representative members of the SlyA/RovA lineage of MarR TFs, which retain some ancestral functions, including repression of their own expression and that of divergently transcribed multidrug efflux pumps, as well as allosteric inhibition by aromatic carboxylate compounds. However, SlyA and RovA have acquired the ability to countersilence horizontally acquired genes, which has greatly facilitated the evolution of Enterobacteriaceae by horizontal gene transfer. SlyA/RovA TFs in different species have independently evolved novel regulatory circuits to provide the enhanced levels of expression required for their new role. Moreover, in contrast to MarR, SlyA is not responsive to copper. These observations demonstrate the ability of TFs to acquire new functions as a result of evolutionary divergence of both cis-regulatory sequences and in trans interactions with modulatory ligands.IMPORTANCE Bacteria primarily evolve via horizontal gene transfer, acquiring new traits such as virulence and antibiotic resistance in single transfer events. However, newly acquired genes must be integrated into existing regulatory networks to allow appropriate expression in new hosts. This is accommodated in part by the opposing mechanisms of xenogeneic silencing and countersilencing. An understanding of these mechanisms is necessary to understand the relationship between gene regulation and bacterial evolution. Here we examine the functional evolution of an important lineage of countersilencers belonging to the ancient MarR family of classical transcriptional repressors. We show that although members of the SlyA lineage retain some ancestral features associated with the MarR family, their cis-regulatory sequences have evolved significantly to support their new function. Understanding the mechanistic requirements for countersilencing is critical to understanding the pathoadaptation of emerging pathogens and also has practical applications in synthetic biology.
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Affiliation(s)
- W Ryan Will
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Peter Brzovic
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Isolde Le Trong
- Department of Biological Structure, University of Washington, Seattle, Washington, USA
| | - Ronald E Stenkamp
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
- Department of Biological Structure, University of Washington, Seattle, Washington, USA
| | - Matthew B Lawrenz
- Department of Microbiology and Immunology and the Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Joyce E Karlinsey
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - William W Navarre
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Kara Main-Hester
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Virginia L Miller
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Stephen J Libby
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
| | - Ferric C Fang
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA
- Department of Microbiology, University of Washington, Seattle, Washington, USA
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199
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Transcriptional noise and exaptation as sources for bacterial sRNAs. Biochem Soc Trans 2019; 47:527-539. [PMID: 30837318 DOI: 10.1042/bst20180171] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 02/01/2019] [Accepted: 02/01/2019] [Indexed: 11/17/2022]
Abstract
Understanding how new genes originate and integrate into cellular networks is key to understanding evolution. Bacteria present unique opportunities for both the natural history and experimental study of gene origins, due to their large effective population sizes, rapid generation times, and ease of genetic manipulation. Bacterial small non-coding RNAs (sRNAs), in particular, many of which operate through a simple antisense regulatory logic, may serve as tractable models for exploring processes of gene origin and adaptation. Understanding how and on what timescales these regulatory molecules arise has important implications for understanding the evolution of bacterial regulatory networks, in particular, for the design of comparative studies of sRNA function. Here, we introduce relevant concepts from evolutionary biology and review recent work that has begun to shed light on the timescales and processes through which non-functional transcriptional noise is co-opted to provide regulatory functions. We explore possible scenarios for sRNA origin, focusing on the co-option, or exaptation, of existing genomic structures which may provide protected spaces for sRNA evolution.
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200
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The Role of the Host in Driving Phenotypic Heterogeneity in Salmonella. Trends Microbiol 2019; 27:508-523. [PMID: 30755344 DOI: 10.1016/j.tim.2019.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/21/2018] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
The complex infection environment within hosts exerts unique stresses across tissues and cell types, selecting for phenotypic heterogeneity in bacterial populations. Pathogens maintain variability during infection as a strategy to cope with fluctuating host immune conditions, leading to diversification of virulence phenotypes. Recent improvements in single-cell analyses have revealed that distinct bacterial subpopulations contribute unique colonization and growth strategies across infection sites. We discuss several examples of host-driven phenotypic heterogeneity in Salmonella populations throughout the course of infection, highlighting how variation in gene expression, growth rate, immune evasion, and metabolic activity contribute to overall bacterial success at the population level. We additionally focus our discussion on the implications of diversity within bacterial communities for antimicrobial efficacy.
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