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  • RNA, Messenger  (16)
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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 23 November 2010, Vol.107(47), pp.20435-40
    Description: The abundant class of bacterial Hfq-associated small regulatory RNAs (sRNAs) parallels animal microRNAs in their ability to control multiple genes at the posttranscriptional level by short and imperfect base pairing. In contrast to the universal length and seed pairing mechanism of microRNAs, the sRNAs are heterogeneous in size and structure, and how they regulate multiple targets is not well understood. This paper provides evidence that a 5' located sRNA domain is a critical element for the control of a large posttranscriptional regulon. We show that the conserved 5' end of RybB sRNA recognizes multiple mRNAs of Salmonella outer membrane proteins by ≥7-bp Watson-Crick pairing. When fused to an unrelated sRNA, the 5' domain is sufficient to guide target mRNA degradation and maintain σ(E)-dependent envelope homeostasis. RybB sites in mRNAs are often conserved and flanked by 3' adenosine. They are found in a wide sequence window ranging from the upstream untranslated region to the deep coding sequence, indicating that some targets might be repressed at the level of translation, whereas others are repressed primarily by mRNA destabilization. Autonomous 5' domains seem more common in sRNAs than appreciated and might improve the design of synthetic RNA regulators.
    Keywords: Bacterial Outer Membrane Proteins -- Metabolism ; Gene Expression Regulation, Bacterial -- Genetics ; RNA, Messenger -- Metabolism ; Regulatory Sequences, Ribonucleic Acid -- Genetics ; Regulon -- Genetics ; Salmonella -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    In: Molecular Microbiology, September 2011, Vol.81(5), pp.1144-1165
    Description: GcvB is one of the most highly conserved Hfq‐associated small RNAs in Gram‐negative bacteria and was previously reported to repress several ABC transporters for amino acids. To determine the full extent of GcvB‐mediated regulation in , we combined a genome‐wide experimental approach with biocomputational target prediction. Comparative pulse expression of wild‐type versus mutant sRNA variants revealed that GcvB governs a large post‐transcriptional regulon, impacting ∼1% of all genes via its conserved G/U‐rich domain R1. Complementary predictions of C/A‐rich binding sites in mRNAs and reporter fusion experiments increased the number of validated GcvB targets to more than 20, and doubled the number of regulated amino acid transporters. Unlike the previously described targeting via the single R1 domain, GcvB represses the glycine transporter CycA by exceptionally redundant base‐pairing. This novel ability of GcvB is focused upon the one target that could feedback‐regulate the glycine‐responsive synthesis of GcvB. Several newly discovered mRNA targets involved in amino acid metabolism, including the global regulator Lrp, question the previous assumption that GcvB simply acts to limit unnecessary amino acid uptake. Rather, GcvB rewires primary transcriptional control circuits and seems to act as a distinct regulatory node in amino acid metabolism.
    Keywords: Glycine -- Physiological Aspects ; Genetic Research -- Physiological Aspects ; Genomics -- Physiological Aspects ; Messenger Rna -- Physiological Aspects;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 3
    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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  • 4
    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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  • 5
    Language: English
    In: PLoS ONE, 01 January 2014, Vol.9(10), p.e110427
    Description: As matchmaker between mRNA and sRNA interactions, the RNA chaperone Hfq plays a key role in riboregulation of many bacteria. Often, the global influence of Hfq on the transcriptome is reflected by substantially altered proteomes and pleiotropic phenotypes in hfq mutants. Using quantitative proteomics and co-immunoprecipitation combined with RNA-sequencing (RIP-seq) of Hfq-bound RNAs, we demonstrate the pervasive role of Hfq in nutrient acquisition, metabolism and motility of the plant pathogen Agrobacterium tumefaciens. 136 of 2544 proteins identified by iTRAQ (isobaric tags for relative and absolute quantitation) were affected in the absence of Hfq. Most of them were associated with ABC transporters, general metabolism and motility. RIP-seq of chromosomally encoded Hfq3xFlag revealed 1697 mRNAs and 209 non-coding RNAs (ncRNAs) associated with Hfq. 56 ncRNAs were previously undescribed. Interestingly, 55% of the Hfq-bound ncRNAs were encoded antisense (as) to a protein-coding sequence suggesting that A. tumefaciens Hfq plays an important role in asRNA-target interactions. The exclusive enrichment of 296 mRNAs and 31 ncRNAs under virulence conditions further indicates a role for post-transcriptional regulation in A. tumefaciens-mediated plant infection. On the basis of the iTRAQ and RIP-seq data, we assembled a comprehensive model of the Hfq core regulon in A. tumefaciens.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 6
    Language: English
    In: Nucleic acids research, November 2012, Vol.40(21), pp.10964-79
    Description: We report on the characterization and target analysis of the small (s)RNA(162) in the methanoarchaeon Methanosarcina mazei. Using a combination of genetic approaches, transcriptome analysis and computational predictions, the bicistronic MM2441-MM2440 mRNA encoding the transcription factor MM2441 and a protein of unknown function was identified as a potential target of this sRNA, which due to processing accumulates as three stabile 5' fragments in late exponential growth. Mobility shift assays using various mutants verified that the non-structured single-stranded linker region of sRNA(162) (SLR) base-pairs with the MM2440-MM2441 mRNA internally, thereby masking the predicted ribosome binding site of MM2441. This most likely leads to translational repression of the second cistron resulting in dis-coordinated operon expression. Analysis of mutant RNAs in vivo confirmed that the SLR of sRNA(162) is crucial for target interactions. Furthermore, our results indicate that sRNA(162)-controlled MM2441 is involved in regulating the metabolic switch between the carbon sources methanol and methylamine. Moreover, biochemical studies demonstrated that the 5' end of sRNA(162) targets the 5'-untranslated region of the cis-encoded MM2442 mRNA. Overall, this first study of archaeal sRNA/mRNA-target interactions unraveled that sRNA(162) acts as an antisense (as)RNA on cis- and trans-encoded mRNAs via two distinct domains, indicating that cis-encoded asRNAs can have larger target regulons than previously anticipated.
    Keywords: Gene Expression Regulation, Archaeal ; RNA, Archaeal -- Chemistry ; RNA, Messenger -- Metabolism ; RNA, Small Untranslated -- Chemistry
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 7
    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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  • 8
    Language: English
    In: Nucleic acids research, October 2010, Vol.38(19), pp.6620-36
    Description: Using an experimental approach, we investigated the RNome of the pathogen Staphylococcus aureus to identify 30 small RNAs (sRNAs) including 14 that are newly confirmed. Among the latter, 10 are encoded in intergenic regions, three are generated by premature transcription termination associated with riboswitch activities, and one is expressed from the complementary strand of a transposase gene. The expression of four sRNAs increases during the transition from exponential to stationary phase. We focused our study on RsaE, an sRNA that is highly conserved in the bacillales order and is deleterious when over-expressed. We show that RsaE interacts in vitro with the 5' region of opp3A mRNA, encoding an ABC transporter component, to prevent formation of the ribosomal initiation complex. A previous report showed that RsaE targets opp3B which is co-transcribed with opp3A. Thus, our results identify an unusual case of riboregulation where the same sRNA controls an operon mRNA by targeting two of its cistrons. A combination of biocomputational and transcriptional analyses revealed a remarkably coordinated RsaE-dependent downregulation of numerous metabolic enzymes involved in the citrate cycle and the folate-dependent one-carbon metabolism. As we observed that RsaE accumulates transiently in late exponential growth, we propose that RsaE functions to ensure a coordinate downregulation of the central metabolism when carbon sources become scarce.
    Keywords: RNA, Small Untranslated -- Metabolism ; Staphylococcus Aureus -- Genetics
    ISSN: 03051048
    E-ISSN: 1362-4962
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  • 9
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 22 December 2009, Vol.106(51), pp.21878-82
    Description: Methanosarcina mazei and related mesophilic archaea are the only organisms fermenting acetate, methylamines, and methanol to methane and carbon dioxide, contributing significantly to greenhouse gas production. The biochemistry of these metabolic processes is well studied, and genome sequences are available, yet little is known about the overall transcriptional organization and the noncoding regions representing 25% of the 4.01-Mb genome of M. mazei. We present a genome-wide analysis of transcription start sites (TSS) in M. mazei grown under different nitrogen availabilities. Pyrosequencing-based differential analysis of primary vs. processed 5' ends of transcripts discovered 876 TSS across the M. mazei genome. Unlike in other archaea, in which leaderless mRNAs are prevalent, the majority of the detected mRNAs in M. mazei carry long untranslated 5' regions. Our experimental data predict a total of 208 small RNA (sRNA) candidates, mostly from intergenic regions but also antisense to 5' and 3' regions of mRNAs. In addition, 40 new small mRNAs with ORFs of 〈 or = 30 aa were identified, some of which might have dual functions as mRNA and regulatory sRNA. We confirmed differential expression of several sRNA genes in response to nitrogen availability. Inspection of their promoter regions revealed a unique conserved sequence motif associated with nitrogen-responsive regulation, which might serve as a regulator binding site upstream of the common IIB recognition element. Strikingly, several sRNAs antisense to mRNAs encoding transposases indicate nitrogen-dependent transposition events. This global TSS map in archaea will facilitate a better understanding of transcriptional and posttranscriptional control in the third domain of life.
    Keywords: Genes, Archaeal ; Methanosarcina -- Genetics ; Nitrogen -- Metabolism ; RNA, Messenger -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 10
    Language: English
    In: Methods, 15 September 2013, Vol.63(2), pp.135-143
    Description: Ribonucleases play key roles in gene regulation and in the expression of virulence factors in . Among these enzymes, the double-strand specific endoribonuclease III (RNase III) is a key mediator of mRNA processing and degradation. Recently, we have defined, direct target sites for RNase III processing on a genome-wide scale in . Our approach is based on deep sequencing of cDNA libraries obtained from RNAs isolated by co-immunoprecipitation with wild-type RNase III and two cleavage-defective mutants. The use of such catalytically inactivated enzymes, which still retain their RNA binding capacity, allows the identification of novel RNA substrates of RNase III. In this report, we will summarize the diversity of RNase III functions, discuss the advantages and the limitations of the approach, and how this strategy identifies novel mRNA targets of small non-coding RNAs in .
    Keywords: Endoribonuclease ; Antisense RNA Regulation ; Regulatory Rnas ; RNA–RNA Interactions ; RNA–Protein Interaction ; Chemistry ; Anatomy & Physiology
    ISSN: 1046-2023
    E-ISSN: 1095-9130
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