Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2007  (34)
Type of Medium
Language
Year
  • 2007  (34)
  • 1
    Language: English
    In: Nucleic acids research, 2007, Vol.35(3), pp.1018-37
    Description: Small non-coding RNAs (sRNAs) are an emerging class of regulators of bacterial gene expression. Most of the regulatory Escherichia coli sRNAs known to date modulate translation of trans-encoded target mRNAs. We studied the specificity of sRNA target interactions using gene fusions to green fluorescent protein (GFP) as a novel reporter of translational control by bacterial sRNAs in vivo. Target sequences were selected from both monocistronic and polycistronic mRNAs. Upon expression of the cognate sRNA (DsrA, GcvB, MicA, MicC, MicF, RprA, RyhB, SgrS and Spot42), we observed highly specific translation repression/activation of target fusions under various growth conditions. Target regulation was also tested in mutants that lacked Hfq or RNase III, or which expressed a truncated RNase E (rne701). We found that translational regulation by these sRNAs was largely independent of full-length RNase E, e.g. despite the fact that ompA fusion mRNA decay could no longer be promoted by MicA. This is the first study in which multiple well-defined E.coli sRNA target pairs have been studied in a uniform manner in vivo. We expect our GFP fusion approach to be applicable to sRNA targets of other bacteria, and also demonstrate that Vibrio RyhB sRNA represses a Vibrio sodB fusion when co-expressed in E.coli.
    Keywords: Gene Expression Regulation, Bacterial ; Protein Biosynthesis ; Escherichia Coli -- Genetics ; RNA, Untranslated -- Metabolism
    ISSN: 03051048
    E-ISSN: 1362-4962
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: Molecular Microbiology, January 2007, Vol.63(1), pp.193-217
    Description: The RNA chaperone, Hfq, plays a diverse role in bacterial physiology beyond its original role as a host factor required for replication of Q RNA bacteriophage. In this study, we show that Hfq is involved in the expression and secretion of virulence factors in the facultative intracellular pathogen, . A deletion strain is highly attenuated in mice after both oral and intraperitoneal infection, and shows a severe defect in invasion of epithelial cells and a growth defect in both epithelial cells and macrophages . Surprisingly, we find that these phenotypes are largely independent of the previously reported requirement of Hfq for expression of the stationary phase sigma factor, RpoS. Our results implicate Hfq as a key regulator of multiple aspects of virulence including regulation of motility and outer membrane protein (OmpD) expression in addition to invasion and intracellular growth. These pleiotropic effects are suggested to involve a network of regulatory small non‐coding RNAs, placing Hfq at the centre of post‐transcriptional regulation of virulence gene expression in . In addition, the mutation appears to cause a chronic activation of the RpoE‐mediated envelope stress response which is likely due to a misregulation of membrane protein expression.
    Keywords: Ribonucleic Acid–RNA ; Gene Expression ; Salmonella ; Genotype & Phenotype ; Proteins ; Cell Growth ; Pathology;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Journal of Molecular Biology, 26 October 2007, Vol.373(3), pp.521-528
    Description: Many bacterial genes of related function are organized in operons and transcribed as polycistronic mRNAs to ensure the coordinate expression of the individual cistrons. Post-transcriptional modulation of such mRNAs can alter the expression of downstream cistrons, resulting in discoordinate protein synthesis from an operon mRNA. Several factors, including small non-coding RNAs (sRNAs), have been described that act collectively as repressors within polycistronic mRNAs. We describe the first case of discoordinated operon expression in which a downstream cistron is activated at the post-transcriptional level. We report that GlmY sRNA activates GlmS synthesis from the mRNA without altering GlmU expression. The sRNA is shown to be structurally and functionally conserved in diverse enterobacteria; its transcription may be controlled by the alternative sigma factor, σ . Our data suggest that Gram-negative bacteria evolved a mechanism of riboregulation that is distinct from the riboswitch mechanism of Gram-positive bacteria.
    Keywords: Small Non-Coding RNA ; Glms ; Discoordinate Operon Expression ; Sigma 54 ; Biology ; Chemistry
    ISSN: 0022-2836
    E-ISSN: 1089-8638
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Nucleic acids research, 2007, Vol.35(22), pp.7651-64
    Description: In pathogenic bacteria, a large number of sRNAs coordinate adaptation to stress and expression of virulence genes. To better understand the turnover of regulatory sRNAs in the model pathogen, Salmonella typhimurium, we have constructed mutants for several ribonucleases (RNase E, RNase G, RNase III, PNPase) and Poly(A) Polymerase I. The expression profiles of four sRNAs conserved among many enterobacteria, CsrB, CsrC, MicA and SraL, were analysed and the processing and stability of these sRNAs was studied in the constructed strains. The degradosome was a common feature involved in the turnover of these four sRNAs. PAPI-mediated polyadenylation was the major factor governing SraL degradation. RNase III was revealed to strongly affect MicA decay. PNPase was shown to be important in the decay of these four sRNAs. The stability of CsrB and CsrC seemed to be independent of the RNA chaperone, Hfq, whereas the decay of SraL and MicA was Hfq-dependent. Taken together, the results of this study provide initial insight into the mechanisms of sRNA decay in Salmonella, and indicate specific contributions of the RNA decay machinery components to the turnover of individual sRNAs.
    Keywords: RNA, Bacterial -- Metabolism ; RNA, Untranslated -- Metabolism ; Ribonucleases -- Physiology ; Salmonella Typhimurium -- Enzymology
    ISSN: 03051048
    E-ISSN: 1362-4962
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Molecular Microbiology, December 2007, Vol.66(5), pp.1174-1191
    Description: The pathogenicity island (SPI‐1) encodes ∼35 proteins involved in assembly of a type III secretion system (T3SS) which endows with the ability to invade eukaryotic cells. We have discovered a novel SPI‐1 gene, , which expresses an abundant small non‐coding RNA (sRNA). The gene, which we identified in a global search for new RNA genes, is activated by the major SPI‐1 transcription factor, HilD, under conditions that favour host cell invasion. The RNA chaperone, Hfq, is essential for the stability of the ∼80 nt InvR RNA. Hfq binds InvR with high affinity , and InvR co‐immunoprecipitates with FLAG epitope‐tagged Hfq in extracts. Surprisingly, deletion/overexpression of revealed no phenotype in SPI‐1 regulation. In contrast, we find that InvR represses the synthesis of the abundant OmpD porin encoded by the core genome. As is conserved in the early branching , we speculate that porin repression by InvR may have aided successful establishment of the SPI‐1 T3SS after horizontal acquisition in the lineage. This study identifies the first regulatory RNA of an enterobacterial pathogenicity island, and new roles for Hfq and HilD in SPI‐1 gene expression.
    Keywords: Biology;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: RNA Biology, 01 July 2007, Vol.4(3), pp.160-164
    Keywords: Anatomy & Physiology
    ISSN: 1547-6286
    E-ISSN: 1555-8584
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Current Opinion in Microbiology, 2007, Vol.10(3), pp.262-270
    Description: Small noncoding RNAs have been discovered at a staggering rate in and many other bacteria. Most of the sRNAs of known function regulate gene expression by binding to specific mRNAs or proteins. Given the scores of sRNAs of unknown function, the identification of their cellular targets has become urgent. Here, we review the diverse strategies that have been used to identify and validate bacterial sRNA targets. These include the pulse-expression of sRNAs followed by global transcriptome analysis (microarrays), new biocomputational prediction algorithms, and novel reporter gene fusions to validate candidate target gene regulation.
    Keywords: Biology
    ISSN: 1369-5274
    E-ISSN: 1879-0364
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Molecular Cell, 11 May 2007, Vol.26(3), pp.381-392
    Description: Most antisense RNAs in bacteria inhibit translation by competing with ribosomes for translation initiation regions (TIRs) on nascent mRNA. We propose a mechanism by which an antisense RNA inhibits translation without binding directly to a TIR. The locus encodes an SOS-induced toxin, and IstR-1 is the antisense RNA that counteracts toxicity. We show that full-length mRNA (+1) is translationally inactive and endonucleolytic processing produces an active mRNA (+42). IstR-1 binding inhibits translation of this mRNA, and subsequent RNase III cleavage generates a truncated, inactive mRNA (+106). In vitro translation, toeprinting, and structure mapping suggest that active, but not inactive, mRNAs contain an upstream ribosome loading or “standby” site. Standby binding is required for initiation at the highly structured TIR. This may involve ribosome sliding to a transiently open TIR. IstR-1 competes with ribosomes by base pairing to the standby site located ∼100 nucleotides upstream.
    Keywords: RNA ; Biology
    ISSN: 1097-2765
    E-ISSN: 1097-4164
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Genes & development, 01 November 2007, Vol.21(21), pp.2804-17
    Description: The interactions of numerous regulatory small RNAs (sRNAs) with target mRNAs have been characterized, but how sRNAs can regulate multiple, structurally unrelated mRNAs is less understood. Here we show that Salmonella GcvB sRNA directly acts on seven target mRNAs that commonly encode periplasmic substrate-binding proteins of ABC uptake systems for amino acids and peptides. Alignment of GcvB homologs of distantly related bacteria revealed a conserved G/U-rich element that is strictly required for GcvB target recognition. Analysis of target gene fusion regulation in vivo, and in vitro structure probing and translation assays showed that GcvB represses its target mRNAs by binding to extended C/A-rich regions, which may also serve as translational enhancer elements. In some cases (oppA, dppA), GcvB repression can be explained by masking the ribosome-binding site (RBS) to prevent 30S subunit binding. However, GcvB can also effectively repress translation by binding to target mRNAs at upstream sites, outside the RBS. Specifically, GcvB represses gltI mRNA translation at the C/A-rich target site located at positions -57 to -45 relative to the start codon. Taken together, our study suggests highly conserved regions in sRNAs and mRNA regions distant from Shine-Dalgarno sequences as important elements for the identification of sRNA targets.
    Keywords: ATP-Binding Cassette Transporters -- Genetics ; Micrornas -- Physiology ; RNA, Messenger -- Metabolism ; Ribosomes -- Metabolism ; Salmonella -- Genetics
    ISSN: 0890-9369
    E-ISSN: 15495477
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Molecular microbiology, December 2007, Vol.66(5), pp.1174-91
    Description: The Salmonella pathogenicity island (SPI-1) encodes approximately 35 proteins involved in assembly of a type III secretion system (T3SS) which endows Salmonella with the ability to invade eukaryotic cells. We have discovered a novel SPI-1 gene, invR, which expresses an abundant small non-coding RNA (sRNA). The invR gene, which we identified in a global search for new Salmonella sRNA genes, is activated by the major SPI-1 transcription factor, HilD, under conditions that favour host cell invasion. The RNA chaperone, Hfq, is essential for the in vivo stability of the approximately 80 nt InvR RNA. Hfq binds InvR with high affinity in vitro, and InvR co-immunoprecipitates with FLAG epitope-tagged Hfq in Salmonella extracts. Surprisingly, deletion/overexpression of invR revealed no phenotype in SPI-1 regulation. In contrast, we find that InvR represses the synthesis of the abundant OmpD porin encoded by the Salmonella core genome. As invR is conserved in the early branching Salmonella bongori, we speculate that porin repression by InvR may have aided successful establishment of the SPI-1 T3SS after horizontal acquisition in the Salmonella lineage. This study identifies the first regulatory RNA of an enterobacterial pathogenicity island, and new roles for Hfq and HilD in SPI-1 gene expression.
    Keywords: Gene Expression Regulation, Bacterial ; Porins -- Biosynthesis ; RNA, Untranslated -- Metabolism ; Salmonella -- Genetics
    ISSN: 0950-382X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages