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  • Helicobacter Pylori
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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 28 January 2014, Vol.111(4), pp.E501-10
    Description: Phase variation of hypermutable simple sequence repeats (SSRs) is a widespread and stochastic mechanism to generate phenotypic variation within a population and thereby contributes to host adaptation of bacterial pathogens. Although several examples of SSRs that affect transcription or coding potential have been reported, we now show that a SSR also impacts small RNA-mediated posttranscriptional regulation. Based on in vitro and in vivo analyses, we demonstrate that a variable homopolymeric G-repeat in the leader of the TlpB chemotaxis receptor mRNA of the human pathogen Helicobacter pylori is directly targeted by a small RNA (sRNA), RepG (Regulator of polymeric G-repeats). Whereas RepG sRNA is highly conserved, the tlpB G-repeat length varies among diverse H. pylori strains, resulting in strain-specific RepG-mediated tlpB regulation. Based on modification of the G-repeat length within one strain, we demonstrate that the G-repeat length determines posttranscriptional regulation and can mediate both repression and activation of tlpB through RepG. In vitro translation assays show that this regulation occurs at the translational level and that RepG influences tlpB translation dependent on the G-repeat length. In contrast to the digital ON-OFF switches through frame-shift mutations within coding sequences, such modulation of posttranscriptional regulation allows for a gradual control of gene expression. This connection to sRNA-mediated posttranscriptional regulation might also apply to other genes with SSRs, which could be targeting sites of cis- or trans-encoded sRNAs, and thereby could facilitate host adaptation through sRNA-mediated fine-tuning of virulence gene expression.
    Keywords: Homopolymeric Repeat ; Noncoding RNA ; Gene Expression Regulation, Bacterial ; RNA Processing, Post-Transcriptional ; Repetitive Sequences, Nucleic Acid ; Chemotaxis -- Genetics ; Helicobacter Pylori -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: Nature, March 11, 2010, Vol.463(7286), p.250(6)
    Description: Genome sequencing of Helicobacter pylori has revealed the potential proteins and genetic diversity of this prevalent human pathogen, yet little is known about its transcriptional organization and noncoding RNA output. Massively parallel cDNA sequencing (RNA-seq) has been revolutionizing global transcriptomic analysis. Here, using a novel differential approach (dRNA-seq) selective for the 5' end of primary transcripts, we present a genome-wide map of H. pylori transcriptional start sites and operons. We discovered hundreds of transcriptional start sites within operons, and opposite to annotated genes, indicating that complexity of gene expression from the small H. pylori genome is increased by uncoupling of polycistrons and by genome-wide antisense transcription. We also discovered an unexpected number of ~60 small RNAs including the e-subdivision counterpart of the regulatory 6S RNA and associated RNA products, and potential regulators of cis- and trans-encoded target messenger RNAs. Our approach establishes a paradigm for mapping and annotating the primary transcriptomes of many living species.
    Keywords: Antisense Rna -- Analysis ; Gene Expression -- Analysis ; Transcription (Genetics) -- Analysis ; Helicobacter Pylori -- Genetic Aspects ; Helicobacter Pylori -- Physiological Aspects
    ISSN: 0028-0836
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  • 3
    Language: English
    In: The Journal of biological chemistry, 03 February 2017, Vol.292(5), pp.1934-1950
    Description: RNA degradation is crucial for regulating gene expression in all organisms. Like the decapping of eukaryotic mRNAs, the conversion of the 5'-terminal triphosphate of bacterial transcripts to a monophosphate can trigger RNA decay by exposing the transcript to attack by 5'-monophosphate-dependent ribonucleases. In both biological realms, this deprotection step is catalyzed by members of the Nudix hydrolase family. The genome of the gastric pathogen Helicobacter pylori, a Gram-negative epsilonproteobacterium, encodes two proteins resembling Nudix enzymes. Here we present evidence that one of them, HP1228 (renamed HpRppH), is an RNA pyrophosphohydrolase that triggers RNA degradation in H. pylori, whereas the other, HP0507, lacks such activity. In vitro, HpRppH converts RNA 5'-triphosphates and diphosphates to monophosphates. It requires at least two unpaired nucleotides at the 5' end of its substrates and prefers three or more but has only modest sequence preferences. The influence of HpRppH on RNA degradation in vivo was examined by using RNA-seq to search the H. pylori transcriptome for RNAs whose 5'-phosphorylation state and cellular concentration are governed by this enzyme. Analysis of cDNA libraries specific for transcripts bearing a 5'-triphosphate and/or monophosphate revealed at least 63 potential HpRppH targets. These included mRNAs and sRNAs, several of which were validated individually by half-life measurements and quantification of their 5'-terminal phosphorylation state in wild-type and mutant cells. These findings demonstrate an important role for RppH in post-transcriptional gene regulation in pathogenic Epsilonproteobacteria and suggest a possible basis for the phenotypes of H. pylori mutants lacking this enzyme.
    Keywords: Helicobacter Pylori ; Nudix ; RNA Degradation ; RNA Modification ; RNA Turnover ; RNA-Protein Interaction ; Deep Sequencing ; Gene Regulation ; Acid Anhydride Hydrolases -- Metabolism ; Bacterial Proteins -- Metabolism ; Gene Expression Regulation, Bacterial -- Physiology ; Helicobacter Pylori -- Metabolism ; RNA Stability -- Physiology ; RNA, Bacterial -- Metabolism ; RNA, Messenger -- Metabolism
    E-ISSN: 1083-351X
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  • 4
    In: Nature, 2010, Vol.464(7286), p.250
    Description: Genome sequencing of Helicobacter pylori has revealed the potential proteins and genetic diversity of this prevalent human pathogen, yet little is known about its transcriptional organization and noncoding RNA output. Massively parallel cDNA sequencing (RNA-seq) has been revolutionizing global transcriptomic analysis. Here, using a novel differential approach (dRNA-seq) selective for the 5' end of primary transcripts, we present a genome-wide map of H. pylori transcriptional start sites and operons. We discovered hundreds of transcriptional start sites within operons, and opposite to annotated genes, indicating that complexity of gene expression from the small H. pylori genome is increased by uncoupling of polycistrons and by genome-wide antisense transcription. We also discovered an unexpected number of approximately 60 small RNAs including the epsilon-subdivision counterpart of the regulatory 6S RNA and associated RNA products, and potential regulators of cis- and trans-encoded target messenger RNAs. Our approach establishes a paradigm for mapping and annotating the primary transcriptomes of many living species.
    Keywords: Gene Expression Profiling ; Genome, Bacterial -- Genetics ; Helicobacter Infections -- Microbiology ; Helicobacter Pylori -- Genetics ; RNA, Bacterial -- Genetics;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 5
    Language: English
    In: Methods, Sept 15, 2015, Vol.86, p.89(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ymeth.2015.06.012 Byline: Thorsten Bischler, Hock Siew Tan, Kay Nieselt, Cynthia M. Sharma Abstract: * A differential RNA-seq (dRNA-seq) approach for primary transcriptome analysis. * dRNA-seq analysis of the gastric pathogen Helicobacter pylori as a model bacterium. * dRNA-seq for global annotation of transcriptional start sites (TSS) and small RNAs. * Comparison of automated and manual TSS annotation. * Variations due to sample and library preparations and sequencing protocols. Article History: Received 8 April 2015; Revised 7 June 2015; Accepted 9 June 2015
    Keywords: Transcription (Genetics) – Genetic Aspects ; Transcription (Genetics) – Analysis ; Helicobacter Pylori – Analysis ; RNA – Genetic Aspects ; RNA – Analysis
    ISSN: 1046-2023
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Nucleic acids research, 29 October 2014, Vol.42(19), pp.11891-902
    Description: Microcin C (McC) is a peptide-nucleotide antibiotic produced by Escherichia coli cells harboring a plasmid-borne operon mccABCDE. The heptapeptide MccA is converted into McC by adenylation catalyzed by the MccB enzyme. Since MccA is a substrate for MccB, a mechanism that regulates the MccA/MccB ratio likely exists. Here, we show that transcription from a promoter located upstream of mccA directs the synthesis of two transcripts: a short highly abundant transcript containing the mccA ORF and a longer minor transcript containing mccA and downstream ORFs. The short transcript is generated when RNA polymerase terminates transcription at an intrinsic terminator located in the intergenic region between the mccA and mccB genes. The function of this terminator is strongly attenuated by upstream mcc sequences. Attenuation is relieved and transcription termination is induced when ribosome binds to the mccA ORF. Ribosome binding also makes the mccA RNA exceptionally stable. Together, these two effects-ribosome-induced transcription termination and stabilization of the message-account for very high abundance of the mccA transcript that is essential for McC production. The general scheme appears to be evolutionary conserved as ribosome-induced transcription termination also occurs in a homologous operon from Helicobacter pylori.
    Keywords: Transcription Termination, Genetic ; Anti-Bacterial Agents -- Biosynthesis ; Bacteriocins -- Biosynthesis ; Escherichia Coli -- Genetics ; Ribosomes -- Metabolism
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 7
    Language: English
    In: Current Opinion in Microbiology, June 2014, Vol.19, pp.97-105
    Description: RNA-sequencing has revolutionized the quantitative and qualitative analysis of transcriptomes in both prokaryotes and eukaryotes. It provides a generic approach for gene expression profiling, annotation of transcript boundaries and operons, as well as identifying novel transcripts including small noncoding RNA molecules and antisense RNAs. We recently developed a differential RNA-seq (dRNA-seq) method which in addition to the above, yields information as to whether a given RNA is a primary or processed transcript. Originally applied to describe the primary transcriptome of the gastric pathogen , dRNA-seq has since provided global maps of transcriptional start sites in diverse species, informed new biology in the CRISPR-Cas9 system, advanced to a tool for comparative transcriptomics, and inspired simultaneous RNA-seq of pathogen and host.
    Keywords: Biology
    ISSN: 1369-5274
    E-ISSN: 1879-0364
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  • 8
    Language: English
    In: Frontiers in cellular and infection microbiology, 2012, Vol.2, pp.14
    Description: The Gram-negative Epsilonproteobacterium Helicobacter pylori is considered as one of the major human pathogens and many studies have focused on its virulence mechanisms as well as genomic diversity. In contrast, only very little is known about post-transcriptional regulation and small regulatory RNAs (sRNAs) in this spiral-shaped microaerophilic bacterium. Considering the absence of the common RNA chaperone Hfq, which is a key-player in post-transcriptional regulation in enterobacteria, H. pylori was even regarded as an organism without riboregulation. However, analysis of the H. pylori primary transcriptome using RNA-seq revealed a very complex transcriptional output from its small genome. Furthermore, the identification of a wealth of sRNAs as well as massive antisense transcription indicates that H. pylori uses riboregulation for its gene expression control. The ongoing functional characterization of sRNAs along with the identification of associated RNA binding proteins will help to understand their potential roles in Helicobacter virulence and stress response. Moreover, research on riboregulation in H. pylori will provide new insights into its virulence mechanisms and will also help to shed light on post-transcriptional regulation in other Epsilonproteobacteria, including widespread and emerging pathogens such as Campylobacter.
    Keywords: Helicobacter Pylori ; RNA-Seq ; Post-Transcriptional Regulation ; Srna ; Transcriptome Analysis ; Gene Expression Regulation, Bacterial ; RNA Interference ; Transcriptome ; Helicobacter Pylori -- Genetics ; RNA, Bacterial -- Metabolism
    E-ISSN: 2235-2988
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  • 9
    Language: English
    In: Methods, 15 September 2015, Vol.86, pp.89-101
    Description: The global mapping of transcription boundaries is a key step in the elucidation of the full complement of transcriptional features of an organism. It facilitates the annotation of operons and untranslated regions as well as novel transcripts, including - and -encoded small RNAs (sRNAs). So called RNA sequencing (RNA-seq) based on deep sequencing of cDNAs has greatly facilitated transcript mapping with single nucleotide resolution. However, conventional RNA-seq approaches typically cannot distinguish between primary and processed transcripts. Here we describe the recently developed differential RNA-seq (dRNA-seq) approach, which facilitates the annotation of transcriptional start sites (TSS) based on deep sequencing of two differentially treated cDNA library pairs, with one library being enriched for primary transcripts. Using the human pathogen as a model organism, we describe the application of dRNA-seq together with an automated TSS annotation approach for generation of a genome-wide TSS map in bacteria. Besides a description of transcriptome and regulatory features that can be identified by this approach, we discuss the impact of different library preparation protocols and sequencing platforms as well as manual and automated TSS annotation. Moreover, we have set up an easily accessible online browser for visualization of the transcriptome data from this and our previous dRNA-seq study.
    Keywords: Differential RNA-Seq ; Transcriptional Start Sites ; Comparative Transcriptomics ; Small Rnas ; Promoter Motifs ; Gene Regulation ; 5′Utr ; Chemistry ; Anatomy & Physiology
    ISSN: 1046-2023
    E-ISSN: 1095-9130
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  • 10
    Language: English
    In: Silence, Oct 25, 2011, Vol.2, p.7
    Description: Background MicroRNAs, post-transcriptional regulators of eukaryotic gene expression, are implicated in host defense against pathogens. Viruses and bacteria have evolved strategies that suppress microRNA functions, resulting in a sustainable infection. In this work we report that Helicobacter pylori, a human stomach-colonizing bacterium responsible for severe gastric inflammatory diseases and gastric cancers, downregulates an embryonic stem cell microRNA cluster in proliferating gastric epithelial cells to achieve cell cycle arrest. Results Using a deep sequencing approach in the AGS cell line, a widely used cell culture model to recapitulate early events of H. pylori infection of gastric mucosa, we reveal that hsa-miR-372 is the most abundant microRNA expressed in this cell line, where, together with hsa-miR-373, it promotes cell proliferation by silencing large tumor suppressor homolog 2 (LATS2) gene expression. Shortly after H. pylori infection, miR-372 and miR-373 synthesis is highly inhibited, leading to the post-transcriptional release of LATS2 expression and thus, to a cell cycle arrest at the G1/S transition. This downregulation of a specific cell-cycle-regulating microRNA is dependent on the translocation of the bacterial effector CagA into the host cells, a mechanism highly associated with the development of severe atrophic gastritis and intestinal-type gastric carcinoma. Conclusions These data constitute a novel example of host-pathogen interplay involving microRNAs, and unveil the couple LATS2/miR-372 and miR-373 as an unexpected mechanism in infection-induced cell cycle arrest in proliferating gastric cells, which may be relevant in inhibition of gastric epithelium renewal, a major host defense mechanism against bacterial infections.
    Keywords: Embryonic Stem Cells -- Physiological Aspects ; Embryonic Stem Cells -- Research ; Helicobacter Pylori -- Genetic Aspects ; Helicobacter Pylori -- Research ; Helicobacter Pylori -- Physiological Aspects ; Microrna -- Physiological Aspects ; Microrna -- Research
    ISSN: 1758-907X
    Source: Cengage Learning, Inc.
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