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  • 1
    Language: English
    In: Nucleic acids research, 07 January 2013, Vol.41(1), pp.542-53
    Description: Many microRNAs (miRNAs) are co-regulated during the same physiological process but the underlying cellular logic is often little understood. The conserved, immunomodulatory miRNAs miR-146 and miR-155, for instance, are co-induced in many cell types in response to microbial lipopolysaccharide (LPS) to feedback-repress LPS signalling through Toll-like receptor TLR4. Here, we report that these seemingly co-induced regulatory RNAs dramatically differ in their induction behaviour under various stimuli strengths and act non-redundantly through functional specialization; although miR-146 expression saturates at sub-inflammatory doses of LPS that do not trigger the messengers of inflammation markers, miR-155 remains tightly associated with the pro-inflammatory transcriptional programmes. Consequently, we found that both miRNAs control distinct mRNA target profiles; although miR-146 targets the messengers of LPS signal transduction components and thus downregulates cellular LPS sensitivity, miR-155 targets the mRNAs of genes pervasively involved in pro-inflammatory transcriptional programmes. Thus, miR-155 acts as a broad limiter of pro-inflammatory gene expression once the miR-146 dependent barrier to LPS triggered inflammation has been breached. Importantly, we also report alternative miR-155 activation by the sensing of bacterial peptidoglycan through cytoplasmic NOD-like receptor, NOD2. We predict that dose-dependent responses to environmental stimuli may involve functional specialization of seemingly co-induced miRNAs in other cellular circuitries as well.
    Keywords: Immunity, Innate -- Genetics ; Micrornas -- Metabolism
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 2
    In: EMBO Journal, 03 July 2013, Vol.32(13), pp.1802-1804
    Description: CRISPR systems not only defend bacteria from foreign DNA but also contribute to pathogenicity, by regulating endogenous gene expression to evade host innate immune responses.
    Keywords: Animals–Immunology ; Female–Pathogenicity ; Gammaproteobacteria–Immunology ; Gammaproteobacteria–Immunology ; Immune Evasion–Immunology ; Immunity, Innate–Immunology ; Germany ; Prokaryotes ; Gene Expression ; Eukaryotes ; Bacteria ; Molecular Biology;
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 3
    In: EMBO Journal, 03 June 2015, Vol.34(11), pp.1478-1492
    Description: There is an expanding list of examples by which one can posttranscriptionally influence the expression of others. This can involve sponges that sequester regulatory s of s in the same regulon, but the underlying molecular mechanism of such cross talk remains little understood. Here, we report sponge‐mediated cross talk in the posttranscriptional network of GcvB, a conserved Hfq‐dependent small with one of the largest regulons known in bacteria. We show that decay from the locus encoding an amino acid transporter generates a stable fragment (SroC) that base‐pairs with GcvB. This interaction triggers the degradation of GcvB by ase E, alleviating the GcvB‐mediated repression of other amino acid‐related transport and metabolic genes. Intriguingly, since the itself is a target of GcvB, the SroC sponge seems to enable both an internal feed‐forward loop to activate its parental in and activation of many ‐encoded s in the same pathway. Disabling this cross talk affects bacterial growth when peptides are the sole carbon and nitrogen sources. Decay of the bacterial GcvB , which keeps it from regulating its targets, is triggered by a 3′‐‐derived fragment from a target . This ability of s to compete for regulatory interaction presents a new mode of cross talk in bacteria. . Decay of the bacterial GcvB s, which keeps it from regulating its m targets, is triggered by a 3′‐‐derived fragment from a target m. This ability of ms to compete for regulatory interaction presents a new mode of cross talk in bacteria.
    Keywords: G Cv B ; H Fq ; Noncoding Rna ; Rn Ase E ; S Ro C
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 4
    In: EMBO Journal, 01 February 2017, Vol.36(3), pp.245-247
    Description: While bacteria were long thought to rely primarily on transcriptional control, it is now well established that they also use numerous small s to regulate translation and stability. There has recently been a surge in studies, including one by Waters ([Waters SA, 2017]) in this issue of , that have used clever variations of the ‐seq technique to comprehensively map small –target networks. Several recent studies have used clever variations of RNA‐seq techniques to comprehensively map small RNA–target networks involved in controlling bacterial gene expression.
    Keywords: Biology ; Chemistry;
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 5
    In: Nucleic Acids Research, 2016, Vol. 44(21), pp.10406-10422
    Description: Model enteric bacteria such as Escherichia coli and Salmonella enterica express hundreds of small non-coding RNAs (sRNAs), targets for most of which are yet unknown. Some sRNAs are remarkably well conserved, indicating that they serve cellular functions that go beyond the necessities of a single species. One of these ‘core sRNAs’ of largely unknown function is the abundant ∼100-nucleotide SdsR sRNA which is transcribed by the general stress σ-factor, σ S and accumulates in stationary phase. In Salmonella , SdsR was known to inhibit the synthesis of the species-specific porin, OmpD. However, sdsR genes are present in almost all enterobacterial genomes, suggesting that additional, conserved targets of this sRNA must exist. Here, we have combined SdsR pulse-expression with whole genome transcriptomics to discover 20 previously unknown candidate targets of SdsR which include mRNAs coding for physiologically important regulators such as the carbon utilization regulator, CRP, the nucleoid-associated chaperone, StpA and the antibiotic resistance transporter, TolC. Processing of SdsR by RNase E results in two cellular SdsR variants with distinct target spectra. While the overall physiological role of this orphan core sRNA remains to be fully understood, the new SdsR targets present valuable leads to determine sRNA functions in resting bacteria.
    Keywords: Chemistry ; Anatomy & Physiology;
    ISSN: 0305-1048
    E-ISSN: 1362-4962
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  • 6
    Language: English
    In: Nucleic acids research, 02 June 2017, Vol.45(10), pp.6147-6167
    Description: Neisseria meningitidis is a human commensal that can also cause life-threatening meningitis and septicemia. Despite growing evidence for RNA-based regulation in meningococci, their transcriptome structure and output of regulatory small RNAs (sRNAs) are incompletely understood. Using dRNA-seq, we have mapped at single-nucleotide resolution the primary transcriptome of N. meningitidis strain 8013. Annotation of 1625 transcriptional start sites defines transcription units for most protein-coding genes but also reveals a paucity of classical σ70-type promoters, suggesting the existence of activators that compensate for the lack of -35 consensus sequences in N. meningitidis. The transcriptome maps also reveal 65 candidate sRNAs, a third of which were validated by northern blot analysis. Immunoprecipitation with the RNA chaperone Hfq drafts an unexpectedly large post-transcriptional regulatory network in this organism, comprising 23 sRNAs and hundreds of potential mRNA targets. Based on this data, using a newly developed gfp reporter system we validate an Hfq-dependent mRNA repression of the putative colonization factor PrpB by the two trans-acting sRNAs RcoF1/2. Our genome-wide RNA compendium will allow for a better understanding of meningococcal transcriptome organization and riboregulation with implications for colonization of the human nasopharynx.
    Keywords: Gene Expression Regulation, Bacterial ; Transcriptome ; Bacterial Proteins -- Metabolism ; Host Factor 1 Protein -- Metabolism ; Micrornas -- Genetics ; Molecular Chaperones -- Metabolism ; Neisseria Meningitidis -- Genetics ; RNA, Bacterial -- Genetics ; RNA, Messenger -- Genetics
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 7
    Language: English
    In: Nucleic acids research, 20 June 2017, Vol.45(11), pp.e96
    Description: RNA-binding proteins (RBPs) have been established as core components of several post-transcriptional gene regulation mechanisms. Experimental techniques such as cross-linking and co-immunoprecipitation have enabled the identification of RBPs, RNA-binding domains (RBDs) and their regulatory roles in the eukaryotic species such as human and yeast in large-scale. In contrast, our knowledge of the number and potential diversity of RBPs in bacteria is poorer due to the technical challenges associated with the existing global screening approaches. We introduce APRICOT, a computational pipeline for the sequence-based identification and characterization of proteins using RBDs known from experimental studies. The pipeline identifies functional motifs in protein sequences using position-specific scoring matrices and Hidden Markov Models of the functional domains and statistically scores them based on a series of sequence-based features. Subsequently, APRICOT identifies putative RBPs and characterizes them by several biological properties. Here we demonstrate the application and adaptability of the pipeline on large-scale protein sets, including the bacterial proteome of Escherichia coli. APRICOT showed better performance on various datasets compared to other existing tools for the sequence-based prediction of RBPs by achieving an average sensitivity and specificity of 0.90 and 0.91 respectively. The command-line tool and its documentation are available at https://pypi.python.org/pypi/bio-apricot.
    Keywords: Sequence Analysis, Protein ; Software ; RNA-Binding Proteins -- Chemistry
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 8
    Language: English
    In: Nucleic acids research, August 2014, Vol.42(14), pp.8845-60
    Description: Phenotypically identical cells can dramatically vary with respect to behavior during their lifespan and this variation is reflected in their molecular composition such as the transcriptomic landscape. Single-cell transcriptomics using next-generation transcript sequencing (RNA-seq) is now emerging as a powerful tool to profile cell-to-cell variability on a genomic scale. Its application has already greatly impacted our conceptual understanding of diverse biological processes with broad implications for both basic and clinical research. Different single-cell RNA-seq protocols have been introduced and are reviewed here-each one with its own strengths and current limitations. We further provide an overview of the biological questions single-cell RNA-seq has been used to address, the major findings obtained from such studies, and current challenges and expected future developments in this booming field.
    Keywords: Gene Expression Profiling -- Methods ; High-Throughput Nucleotide Sequencing -- Methods ; Sequence Analysis, RNA -- Methods ; Single-Cell Analysis -- Methods
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 9
    In: EMBO Journal, 17 October 2012, Vol.31(20), pp.4005-4019
    Description: The small RNAs associated with the protein Hfq constitute one of the largest classes of post‐transcriptional regulators known to date. Most previously investigated members of this class are encoded by conserved free‐standing genes. Here, deep sequencing of Hfq‐bound transcripts from multiple stages of growth of revealed a plethora of new small RNA species from within mRNA loci, including DapZ, which overlaps with the 3′ region of the biosynthetic gene, . Synthesis of the DapZ small RNA is independent of DapB protein synthesis, and is controlled by HilD, the master regulator of invasion genes. DapZ carries a short G/U‐rich domain similar to that of the globally acting GcvB small RNA, and uses GcvB‐like seed pairing to repress translation of the major ABC transporters, DppA and OppA. This exemplifies double functional output from an mRNA locus by the production of both a protein and an Hfq‐dependent ‐acting RNA. Our atlas of Hfq targets suggests that the 3′ regions of mRNA genes constitute a rich reservoir that provides the Hfq network with new regulatory small RNAs. Deep sequencing of Hfq‐binding RNAs isolated from at different growth stages reveals that the 3′ UTR of bacterial mRNAs are a rich source of regulatory small RNAs which modulate gene expression in trans.
    Keywords: Abc Transporter ; Dapz ; Gcvb ; Hfq ; 3′ Utr
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 10
    In: EMBO Journal, 13 April 2017, Vol.36(8), pp.1029-1045
    Description: Research into post‐transcriptional control of mRNAs by small noncoding RNAs (sRNAs) in the model bacteria and has mainly focused on sRNAs that associate with the RNA chaperone Hfq. However, the recent discovery of the protein ProQ as a common binding partner that stabilizes a distinct large class of structured sRNAs suggests that additional RNA regulons exist in these organisms. The cellular functions and molecular mechanisms of these new ProQ‐dependent sRNAs are largely unknown. Here, we report in Typhimurium the mode‐of‐action of RaiZ, a ProQ‐dependent sRNA that is made from the 3′ end of the mRNA encoding ribosome‐inactivating protein RaiA. We show that RaiZ is a base‐pairing sRNA that represses in the mRNA of histone‐like protein HU‐α. RaiZ forms an RNA duplex with the ribosome‐binding site of mRNA, facilitated by ProQ, to prevent 30S ribosome loading and protein synthesis of HU‐α. Similarities and differences between ProQ‐ and Hfq‐mediated regulation will be discussed. The enterobacterial sRNA RaiZ functions independent of the Hfq RNA chaperone via the recently identified general RNA‐binding protein ProQ. ProQ acts in a dual manner, stabilizing the sRNA and facilitating translational repression of the nucleid protein HU‐α. RaiZ is a small RNA produced by RNase E‐mediated cleavage of the raiA mRNA. RaiZ strongly binds RNA chaperone ProQ, leading to RaiZ stabilization. RaiZ represses translation of the hupA mRNA by base pairing with its ribosome‐binding site. ProQ and RaiZ jointly prevent initiating ribosomes from loading on hupA mRNA. The global RNA‐binding protein ProQ stabilizes bacterial small RNA RaiZ and facilitates translational repression of its target mRNA, thus exemplifying an Hfq‐independent RNA regulon.
    Keywords: Hu‐Α ; Proq ; Raiz ; Small Rna ; Translation Inhibition
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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