Kooperativer Bibliotheksverbund

Berlin Brandenburg

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  • 2018  (52)
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  • 2018  (52)
  • 1
    Language: English
    In: Science (New York, N.Y.), 07 December 2018, Vol.362(6419), pp.1156-1160
    Description: Many bacterial infections are hard to treat and tend to relapse, possibly due to the presence of antibiotic-tolerant persisters. In vitro, persister cells appear to be dormant. After uptake of species by macrophages, nongrowing persisters also occur, but their physiological state is poorly understood. In this work, we show that persisters arising during macrophage infection maintain a metabolically active state. Persisters reprogram macrophages by means of effectors secreted by the pathogenicity island 2 type 3 secretion system. These effectors dampened proinflammatory innate immune responses and induced anti-inflammatory macrophage polarization. Such reprogramming allowed nongrowing cells to survive for extended periods in their host. Persisters undermining host immune defenses might confer an advantage to the pathogen during relapse once antibiotic pressure is relieved.
    Keywords: Drug Resistance, Bacterial ; Host-Pathogen Interactions -- Immunology ; Macrophages -- Immunology ; Salmonella Infections -- Drug Therapy ; Salmonella Typhimurium -- Metabolism ; Type III Secretion Systems -- Metabolism
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    In: EMBO Journal, 02 July 2018, Vol.37(13), pp.n/a-n/a
    Description: Long non‐coding s (lncs) play important roles in many cellular pathways, but their contribution to the defense of eukaryotic cells against pathogens remains poorly understood. A new study from Imamura in reports that infection in human cells impacts nuclear decay, which in turn drives the accumulation of otherwise unstable nuclear lncs, some of which may have protective effects against this common bacterial pathogen. These unexpected findings demand more efforts to fully decrypt the molecular functions of lncs in innate and adaptive immunity. infection impairs the nuclear RNA decay machinery in human cells, increasing the abundance of long non‐coding RNAs with a role in innate immunity.
    Keywords: Pathogens ; Immunity ; Infections ; Pathogens ; Molecular Chains ; Salmonella ; Bacterial Infections ; Pathogens ; Ribonucleic Acid–RNA ; Ribonucleic Acid–RNA ; Adaptive Immunity;
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 3
    Language: English
    In: Nature, November 2018, Vol.563(7729), pp.121-125
    Description: Many evolutionarily distant pathogenic organisms have evolved similar survival strategies to evade the immune responses of their hosts. These include antigenic variation, through which an infecting organism prevents clearance by periodically altering the identity of proteins that are visible to the immune system of the host. Antigenic variation requires large reservoirs of immunologically diverse antigen genes, which are often generated through homologous recombination, as well as mechanisms to ensure the expression of one or very few antigens at any given time. Both homologous recombination and gene expression are affected by three-dimensional genome architecture and local DNA accessibility. Factors that link three-dimensional genome architecture, local chromatin conformation and antigenic variation have, to our knowledge, not yet been identified in any organism. One of the major obstacles to studying the role of genome architecture in antigenic variation has been the highly repetitive nature and heterozygosity of antigen-gene arrays, which has precluded complete genome assembly in many pathogens. Here we report the de novo haplotype-specific assembly and scaffolding of the long antigen-gene arrays of the model protozoan parasite Trypanosoma brucei, using long-read sequencing technology and conserved features of chromosome folding. Genome-wide chromosome conformation capture (Hi-C) reveals a distinct partitioning of the genome, with antigen-encoding subtelomeric regions that are folded into distinct, highly compact compartments. In addition, we performed a range of analyses-Hi-C, fluorescence in situ hybridization, assays for transposase-accessible chromatin using sequencing and single-cell RNA sequencing-that showed that deletion of the histone variants H3.V and H4.V increases antigen-gene clustering, DNA accessibility across sites of antigen expression and switching of the expressed antigen isoform, via homologous recombination. Our analyses identify histone variants as a molecular link between global genome architecture, local chromatin conformation and antigenic variation.
    Keywords: Antigenic Variation -- Genetics ; Chromatin -- Genetics ; DNA, Protozoan -- Metabolism ; Genome -- Genetics ; Trypanosoma Brucei Brucei -- Genetics
    ISSN: 00280836
    E-ISSN: 1476-4687
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  • 4
    Language: English
    In: Nature Reviews Microbiology, 2018, Vol.16(10), pp.601-615
    Description: RNA-binding proteins (RBPs) are central to most if not all cellular processes, dictating the fate of virtually all RNA molecules in the cell. Starting with pioneering work on ribosomal proteins, studies of bacterial RBPs have paved the way for molecular studies of RNA-protein interactions. Work over...
    Keywords: Medical And Health Sciences ; Basic Medicine ; Microbiology In The Medical Area ; Medicin Och Hälsovetenskap ; Medicinska Och Farmaceutiska Grundvetenskaper ; Mikrobiologi Inom Det Medicinska Området
    ISSN: 1740-1526
    E-ISSN: 17401534
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  • 5
    In: EMBO Journal, 03 December 2018, Vol.37(23), pp.n/a-n/a
    Description: While mucosal inflammation is a major source of stress during enteropathogen infection, it remains to be fully elucidated how the host benefits from this environment to clear the pathogen. Here, we show that host stress induced by different stimuli mimicking inflammatory conditions strongly reduces the binding of to epithelial cells. Mechanistically, stress activates acid sphingomyelinase leading to host membrane remodeling. Consequently, knockdown or pharmacological inhibition of the acid sphingomyelinase blunts the stress‐dependent inhibition of binding to host cells. Interestingly, stress caused by intracellular replication also results in remodeling of the host cell membrane, and , which precludes re‐infection by this and other non‐motile pathogens. In contrast, Typhimurium overcomes the shortage of permissive entry sites by gathering effectively at the remaining platforms through its flagellar motility. Overall, our findings reveal host membrane remodeling as a novel stress‐responsive cell‐autonomous defense mechanism that protects epithelial cells from infection by non‐motile bacterial pathogens. Stress‐induced host membrane remodeling constitutes a novel cell‐autonomous defensive mechanism that protects epithelial cells from infection by and other non‐motile bacterial pathogens. Host oxidative stress strongly reduces S. flexneri binding to epithelial cells. Stress leads to host membrane remodeling, via activation of the acid sphingomyelinase by the MAPK p38 pathway, resulting in the formation of ceramide domains. Intracellular Shigella replication induces remodeling of the host cell membrane, in vitro and in vivo. Stress‐induced host membrane remodeling precludes re‐infection by non‐motile pathogens; motile pathogens are able to overcome this barrier through flagellar motility. Host membrane remodeling is a cell‐autonomous defense mechanism that protects epithelial cells from infection by .
    Keywords: Acid Sphingomyelinase ; Host Stress Response ; Membrane Remodeling ; Salmonella ; Shigella
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 6
    Language: English
    In: Methods in molecular biology (Clifton, N.J.), 2018, Vol.1737, pp.59-75
    Description: Transcriptomics, i.e., the quantification of cellular RNA transcripts, is a powerful way to gauge the physiological state of either bacterial or eukaryotic cells under a given condition. However, traditional approaches were unsuitable to measure the abundance of transcripts across kingdoms, which is relevant for biological processes such as bacterial infections of mammalian host cells. This changed with the establishment of "Dual RNA-seq," which profiles gene expression simultaneously in an infecting bacterium and its infected host. Here, we describe a detailed Dual RNA-seq protocol optimized for-but not restricted to-the study of human cell culture models infected with the Gram-negative model pathogen Salmonella Typhimurium. Furthermore, we provide experimental data demonstrating the benefits of some of the key steps of this protocol, including transcriptome stabilization (RNA fixation), FACS-based enrichment of invaded cells, and double rRNA depletion. While our focus is on data generation, we also include a section describing suitable computational methods to analyze the obtained datasets.
    Keywords: Cell Sorting ; Dual RNA-Seq ; Fixation ; Host-Pathogen Interaction ; Infection ; Noncoding RNA ; RNA-Seq ; Salmonella ; Transcriptomics ; Rrna Depletion ; Gene Expression Profiling ; Host-Pathogen Interactions ; Computational Biology -- Methods ; High-Throughput Nucleotide Sequencing -- Methods ; Salmonella Infections -- Microbiology ; Salmonella Typhimurium -- Genetics ; Sequence Analysis, RNA -- Methods
    E-ISSN: 1940-6029
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 7
    Language: English
    In: Molecular Cell, 07 June 2018, Vol.70(5), pp.785-799
    Description: Bacteria are an exceedingly diverse group of organisms whose molecular exploration is experiencing a renaissance. While the classical view of bacterial gene expression was relatively simple, the emerging view is more complex, encompassing extensive post-transcriptional control involving riboswitches, RNA thermometers, and regulatory small RNAs (sRNAs) associated with the RNA-binding proteins CsrA, Hfq, and ProQ, as well as CRISPR/Cas systems that are programmed by RNAs. Moreover, increasing interest in members of the human microbiota and environmental microbial communities has highlighted the importance of understudied bacterial species with largely unknown transcriptome structures and RNA-based control mechanisms. Collectively, this creates a need for global RNA biology approaches that can rapidly and comprehensively analyze the RNA composition of a bacterium of interest. We review such approaches with a focus on RNA-seq as a versatile tool to investigate the different layers of gene expression in which RNA is made, processed, regulated, modified, translated, and turned over. RNA-seq-based approaches are revolutionizing how bacterial RNA biology can be studied. Hör, Gorski, and Vogel review the available global methods that can be used to chart the increasingly diverse number of RNA species and functions in any microbe of interest.
    Keywords: RNA-Seq ; Non-Coding RNA ; Small RNA ; Transcription ; RNA-Binding Protein ; Post-Transcriptional Control ; Biology
    ISSN: 1097-2765
    E-ISSN: 1097-4164
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  • 8
    Language: English
    In: Molecular Cell, 07 June 2018, Vol.70(5), pp.971-982.e6
    Description: The conserved RNA-binding protein ProQ has emerged as the centerpiece of a previously unknown third large network of post-transcriptional control in enterobacteria. Here, we have used UV crosslinking and RNA sequencing (CLIP-seq) to map hundreds of ProQ binding sites in and . Our analysis of these binding sites, many of which are conserved, suggests that ProQ recognizes its cellular targets through RNA structural motifs found in small RNAs (sRNAs) and at the 3′ end of mRNAs. Using the mRNA as a model for 3′ end targeting, we reveal a function for ProQ in protecting mRNA against exoribonucleolytic activity. Taken together, our results underpin the notion that ProQ governs a post-transcriptional network distinct from those of the well-characterized sRNA-binding proteins, CsrA and Hfq, and suggest a previously unrecognized, sRNA-independent role of ProQ in stabilizing mRNAs. Using CLIP-seq, Holmqvist et al. map transcriptome-wide interactions of the emerging global RNA-binding protein ProQ in and . Their data suggest ProQ to target sRNAs and mRNA 3′ UTRs primarily through a structural code and to stabilize some mRNAs by counteracting 3′ exoribonuclease activity.
    Keywords: Proq ; Clip-Seq ; RNA-Binding Protein ; 3′ Utr ; Post-Transcriptional Control ; Exoribonuclease ; Biology
    ISSN: 1097-2765
    E-ISSN: 1097-4164
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  • 9
    In: mBio, 2018, Vol.9(6)
    Description: The alphaproteobacterium Agrobacterium tumefaciens is able to infect various eudicots causing crown gall tumor formation. Based on its unique ability of interkingdom gene transfer, Agrobacterium serves as a crucial biotechnological tool for genetic manipulation of plant cells. The presence of hundreds of putative sRNAs in this organism suggests a considerable impact of riboregulation on A. tumefaciens physiology. Here, we characterized the biological function of the sRNA PmaR that controls various processes crucial for growth, motility, and virulence. Among the genes directly targeted by PmaR is ampC coding for a beta-lactamase that confers ampicillin resistance, suggesting that the sRNA is crucial for fitness in the competitive microbial composition of the rhizosphere. ABSTRACT Small regulatory RNAs play an important role in the adaptation to changing conditions. Here, we describe a differentially expressed small regulatory RNA (sRNA) that affects various cellular processes in the plant pathogen Agrobacterium tumefaciens . Using a combination of bioinformatic predictions and comparative proteomics, we identified nine targets, most of which are positively regulated by the sRNA. According to these targets, we named the sRNA PmaR for peptidoglycan biosynthesis, motility, and ampicillin resistance regulator. Agrobacterium spp. are long known to be naturally resistant to high ampicillin concentrations, and we can now explain this phenotype by the positive PmaR-mediated regulation of the beta-lactamase gene ampC . Structure probing revealed a spoon-like structure of the sRNA, with a single-stranded loop that is engaged in target interaction in vivo and in vitro . Several riboregulators have been implicated in antibiotic resistance mechanisms, such as uptake and efflux transporters, but PmaR represents the first example of an sRNA that directly controls the expression of an antibiotic resistance gene.
    Keywords: Research Article ; Molecular Biology And Physiology ; Antibiotic Resistance ; Gene Regulation ; Plant-Microbe Interaction ; Posttranscriptional Control ; Regulatory Rna
    ISSN: 21612129
    E-ISSN: 2150-7511
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  • 10
    In: mBio, 2018, Vol.9(6)
    Description: P. aeruginosa is a soil dwelling bacterium and a plant pathogen, and it also causes life-threatening infections in humans. Thus, P. aeruginosa thrives in diverse environments and over a broad range of temperatures. Some P. aeruginosa strains rely on the CRISPR-Cas adaptive immune system as a phage defense mechanism. Our discovery that low temperatures increase CRISPR adaptation suggests that the rarely occurring but crucial naive adaptation events may take place predominantly under conditions of slow growth, e.g., during the bacterium’s soil dwelling existence and during slow growth in biofilms. ABSTRACT Clustered regularly interspaced short palindromic repeat (CRISPR)-associated (CRISPR-Cas) systems are adaptive defense systems that protect bacteria and archaea from invading genetic elements. In Pseudomonas aeruginosa , quorum sensing (QS) induces the CRISPR-Cas defense system at high cell density when the risk of bacteriophage infection is high. Here, we show that another cue, temperature, modulates P. aeruginosa CRISPR-Cas. Increased CRISPR adaptation occurs at environmental (i.e., low) temperatures compared to that at body (i.e., high) temperature. This increase is a consequence of the accumulation of CRISPR-Cas complexes, coupled with reduced P. aeruginosa growth rate at the lower temperature, the latter of which provides additional time prior to cell division for CRISPR-Cas to patrol the cell and successfully eliminate and/or acquire immunity to foreign DNA. Analyses of a QS mutant and synthetic QS compounds show that the QS and temperature cues act synergistically. The diversity and level of phage encountered by P. aeruginosa in the environment exceed that in the human body, presumably warranting increased reliance on CRISPR-Cas at environmental temperatures.
    Keywords: Research Article ; Molecular Biology And Physiology ; Crispr ; Phage ; Pseudomonas ; Quorum Sensing ; Growth Rate
    ISSN: 21612129
    E-ISSN: 2150-7511
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