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
  • 2008  (38)
Type of Medium
Language
Year
  • 2008  (38)
  • 1
    Language: English
    In: PLoS Biology, 2008, Vol.6(3), p.e64
    Description: Small noncoding RNAs (sRNA) can function as posttranscriptional activators of gene expression to regulate stress responses and metabolism. We here describe the mechanisms by which two sRNAs, GlmY and GlmZ, activate the Escherichia coli glmS mRNA, coding for an essential enzyme in amino-sugar metabolism. The two sRNAs, although being highly similar in sequence and structure, act in a hierarchical manner. GlmZ, together with the RNA chaperone, Hfq, directly activates glmS mRNA translation by an anti-antisense mechanism. In contrast, GlmY acts upstream of GlmZ and positively regulates glmS by antagonizing GlmZ RNA inactivation. We also report the first example, to our knowledge, of mRNA expression being controlled by the poly(A) status of a chromosomally encoded sRNA. We show that in wild-type cells, GlmY RNA is unstable due to 3′ end polyadenylation; whereas in an E. coli pcnB mutant defective in RNA polyadenylation, GlmY is stabilized and accumulates, which in turn stabilizes GlmZ and causes GlmS overproduction. Our study reveals hierarchical action of two well-conserved sRNAs in a complex regulatory cascade that controls the glmS mRNA. Similar cascades of noncoding RNA regulators may operate in other organisms. ; Hierarchical action of regulators is a fundamental principle in gene expression control, and is well understood in protein-based signaling pathways. We have discovered that small noncoding RNAs (sRNAs), a new class of gene expression regulators, can also act hierarchically and form a regulatory cascade. Two highly similar sRNAs function after transcription to activate the mRNA, which codes for an essential function in amino-sugar metabolism. It is somewhat unusual for two sRNAs to act upon the same target mRNA, and despite their seeming homology, these two sRNAs (GlmY and GlmZ) employ different molecular mechanisms and function hierarchically to activate expression: GlmZ directly activates translation via disruption of an mRNA structure that inhibits translation, whereas GlmY controls the processing of GlmZ to prevent the inactivation of this direct activator. We also found that GlmY is itself controlled by an RNA processing event (3′ end polyadenylation), which typically destabilizes bacterial RNA. Our data unequivocally demonstrate that is exceptionally dependent on RNA-based mechanisms for its genetic control. Given the large number of noncoding RNAs of unknown function, we believe that similar regulatory RNA cascades may operate in other organisms. ; A regulatory RNA cascade that posttranscriptionally activates the mRNA is identified, with two highly similar small noncoding RNAs acting hierarchically in a manner thus far known only in protein-based regulatory circuits.
    Keywords: Research Article ; Biochemistry ; Genetics And Genomics ; Molecular Biology
    ISSN: 1544-9173
    E-ISSN: 1545-7885
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: Molecular Microbiology, May 2008, Vol.68(4), pp.890-906
    Description: Post‐transcriptional repression of porin synthesis has emerged as a major function of Hfq‐dependent, small non‐coding RNAs (sRNAs). Many enterobacteria express OmpX‐like porins, a family of outer membrane proteins whose physiological roles and structural properties have been studied intensively. While regulatory sRNAs have been identified for most major and many minor porins of and , a post‐transcriptional regulator of OmpX levels has never been found. Here, we have taken a ‘reverse target search’ approach by systematic inactivation of sRNA genes, and screening 35 sRNA deletion strains for effects on OmpX synthesis. We have identified the Hfq‐dependent CyaR (formerly RyeE) sRNA as an repressor. Global transcriptomic profiling following induction of CyaR expression suggests that mRNA is the primary target of this sRNA under standard growth conditions. The results of phylogenetic and mutational analyses suggest that a conserved RNA hairpin of CyaR, featuring a C‐rich apical loop, acts to sequester the Shine–Dalgarno sequence of mRNA and to inhibit translational initiation. We have also discovered that expression is tightly controlled by the cyclic AMP receptor protein, CRP. This represents a new link between porin repression and nutrient availability that is likely to be widely conserved among enterobacteria.
    Keywords: Genetic Research -- Genetic Aspects ; Genetic Research -- Physiological Aspects ; Bacterial Genetics -- Genetic Aspects ; Bacterial Genetics -- Physiological Aspects ; Cyclic Adenosine Monophosphate -- Genetic Aspects ; Cyclic Adenosine Monophosphate -- Physiological Aspects ; Salmonella -- Genetic Aspects ; Salmonella -- Physiological Aspects ; Rna -- Genetic Aspects ; Rna -- Physiological Aspects ; Porins -- Genetic Aspects ; Porins -- Physiological Aspects;
    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: Cell Host & Microbe, 2008, Vol.4(4), pp.310-312
    Description: Studies of the accessory gene regulator ( agr) of Staphylococcus aureus often focus on the associated RNA regulator RNAIII. Recently, Queck et al. (2008) reported on RNAIII-independent gene regulation in highly virulent, community-associated S. aureus and proposed that two independent regulatory systems were integrated during the pathogenic evolution of S. aureus.
    Keywords: Evolution, Molecular ; Gene Expression Regulation, Bacterial ; Staphylococcus Aureus -- Pathogenicity ; Virulence Factors -- Biosynthesis;
    ISSN: 1931-3128
    E-ISSN: 19346069
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Genes & development, 01 November 2008, Vol.22(21), pp.2914-25
    Description: Noncoding RNA regulators have been implicated in almost all imaginable cellular processes. Here we review how regulatory small RNAs such as Spot42, SgrS, GlmY, and GlmZ and a cis-encoded ribozyme in glmS mRNA control sugar metabolism. Besides discussing the physiological implications, we show how the study of these molecules contributed to our understanding of the mechanisms and of general principles of RNA-based regulation. These include the post-transcriptional repression or activation of gene expression within polycistronic mRNAs; novel ribonucleoprotein complexes composed of small RNA, Hfq, and/or RNase E; and the hierarchical action of regulatory RNAs.
    Keywords: Carbohydrate Metabolism ; Bacterial Proteins -- Metabolism ; RNA, Bacterial -- Metabolism ; RNA, Untranslated -- Metabolism
    ISSN: 0890-9369
    E-ISSN: 15495477
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Molecular Microbiology, October 2008, Vol.70(1), pp.100-111
    Description: We discovered a new small non‐coding RNA (sRNA) gene, of O1 strain A1552. A mutant overproduces OmpA porin, and we demonstrate that the 140 nt VrrA RNA represses translation by base‐pairing with the 5′ region of the mRNA. The RNA chaperone Hfq is not stringently required for VrrA action, but expression of the gene requires the membrane stress sigma factor, σ, suggesting that VrrA acts on in response to periplasmic protein folding stress. We also observed that OmpA levels inversely correlated with the number of outer membrane vesicles (OMVs), and that VrrA increased OMV production comparable to loss of OmpA. VrrA is the first sRNA known to control OMV formation. Moreover, a mutant showed a fivefold increased ability to colonize the intestines of infant mice as compared with the wild type. There was increased expression of the main colonization factor of , the toxin co‐regulated pili, in the mutant as monitored by immunoblot detection of the TcpA protein. VrrA overproduction caused a distinct reduction in the TcpA protein level. Our findings suggest that VrrA contributes to bacterial fitness in certain stressful environments, and modulates infection of the host intestinal tract.
    Keywords: Cholera ; Ribonucleic Acid–RNA ; Bacteria ; Membranes ; Mutation ; Gene Expression ; Proteins ; Microbiology;
    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: Molecular Cell, 2008, Vol.32(6), pp.827-837
    Description: Small noncoding RNAs (sRNAs) have predominantly been shown to repress bacterial mRNAs by masking the Shine-Dalgarno (SD) or AUG start codon sequence, thereby preventing 30S ribosome entry and, consequently, translation initiation. However, many recently identified sRNAs lack obvious SD and AUG complementarity, indicating that sRNA-mediated translational control could also take place at other mRNA sites. We report that Salmonella RybB sRNA represses ompN mRNA translation by pairing with the 5′ coding region. Results of systematic antisense interference with 30S binding to ompN and unrelated mRNAs suggest that sRNAs can act as translational repressors by sequestering sequences within the mRNA down to the fifth codon, even without SD and AUG start codon pairing. This “five codon window” for translational control in the 5′ coding region of mRNA not only has implications for sRNA target predictions but might also apply to cis-regulatory systems such as RNA thermosensors and riboswitches.
    Keywords: RNA ; Microbio
    ISSN: 1097-2765
    E-ISSN: 10974164
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Microbiology (Reading, England), October 2008, Vol.154(Pt 10), pp.3134-3143
    Description: The ssr3341 locus was previously suggested to encode an orthologue of the RNA chaperone Hfq in the cyanobacterium Synechocystis sp. strain PCC 6803. Insertional inactivation of this gene resulted in a mutant that was not naturally transformable and exhibited a non-phototactic phenotype compared with the wild-type. The loss of motility was complemented by reintroduction of the wild-type gene, correlated with the re-establishment of type IV pili on the cell surface. Microarray analyses revealed a small set of genes with drastically reduced transcript levels in the knockout mutant compared with the wild-type cells. Among the most strongly affected genes, slr1667, slr1668, slr2015, slr2016 and slr2018 stood out, as they belong to two operons that had previously been shown to be involved in motility, controlled by the cAMP receptor protein SYCRP1. This suggests a link between cAMP signalling, motility and possibly the involvement of RNA-based regulation. This is believed to be the first report demonstrating a functional role of an Hfq orthologue in cyanobacteria, establishing a new factor in the control of motility.
    Keywords: Bacterial Proteins -- Genetics ; Molecular Chaperones -- Genetics ; Synechocystis -- Genetics
    ISSN: 1350-0872
    E-ISSN: 14652080
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: PLoS Genetics, 2008, Vol.4(8), p.e1000163
    Description: Recent advances in high-throughput pyrosequencing (HTPS) technology now allow a thorough analysis of RNA bound to cellular proteins, and, therefore, of post-transcriptional regulons. We used HTPS to discover the Salmonella RNAs that are targeted by the common bacterial Sm-like protein, Hfq. Initial transcriptomic analysis revealed that Hfq controls the expression of almost a fifth of all Salmonella genes, including several horizontally acquired pathogenicity islands (SPI-1, -2, -4, -5), two sigma factor regulons, and the flagellar gene cascade. Subsequent HTPS analysis of 350,000 cDNAs, derived from RNA co-immunoprecipitation (coIP) with epitope-tagged Hfq or control coIP, identified 727 mRNAs that are Hfq-bound in vivo . The cDNA analysis discovered new, small noncoding RNAs (sRNAs) and more than doubled the number of sRNAs known to be expressed in Salmonella to 64; about half of these are associated with Hfq. Our analysis explained aspects of the pleiotropic effects of Hfq loss-of-function. Specifically, we found that the mRNAs of hilD (master regulator of the SPI-1 invasion genes) and flhDC (flagellar master regulator) were bound by Hfq. We predicted that defective SPI-1 secretion and flagellar phenotypes of the hfq mutant would be rescued by overexpression of HilD and FlhDC, and we proved this to be correct. The combination of epitope-tagging and HTPS of immunoprecipitated RNA detected the expression of many intergenic chromosomal regions of Salmonella . Our approach overcomes the limited availability of high-density microarrays that have impeded expression-based sRNA discovery in microorganisms. We present a generic strategy that is ideal for the systems-level analysis of the post-transcriptional regulons of RNA-binding proteins and for sRNA discovery in a wide range of bacteria. ; The past decade has seen small regulatory RNA become an important new mediator of bacterial mRNA regulation. This study describes a rapid way to identify novel sRNAs that are expressed, and should prove relevant to a variety of bacteria. We purified the epitope-tagged RNA-binding protein, Hfq, and its bound RNA by immunoprecipitation from the model pathogen, serovar Typhimurium. This new strategy used Next Generation pyrosequencing to identify 727 Hfq-bound mRNAs. The numbers of sRNAs expressed in was doubled to 64; half are associated with Hfq. We defined the exact coordinates of sRNAs, and confirmed that they are expressed at significant levels. We also determined the Hfq regulon in , and reported the role of Hfq in controlling transcription of major pathogenicity islands, horizontally acquired regions, and the flagellar cascade. Hfq is reported to be a global regulator that affects the expression of almost a fifth of all genes. Our new approach will allow sRNAs and mRNAs to be characterized from different genetic backgrounds, or from bacteria grown under particular environmental conditions. It will be valuable to scientists working on genetically tractable bacteria who are interested in the function of RNA-binding proteins and the identification of sRNAs.
    Keywords: Research Article ; Biochemistry -- Bioinformatics ; Genetics And Genomics -- Functional Genomics ; Genetics And Genomics -- Gene Expression ; Microbiology ; Microbiology -- Microbial Evolution And Genomics
    ISSN: 1553-7390
    E-ISSN: 1553-7404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    Description: With around 3 billion subscribers, GSM is the world's most commonly used technology for wireless communication. Providing an overview of the innovations that have fuelled this phenomena, 〈i〉GSM: Architecture, Protocols and Services, Third Edition〈/i〉 offers a clear introduction to the field of cellular systems. Special emphasis is placed on system architecture and protocol aspects, and topics range from addressing concepts through mobility management to network management.〈p〉〈p〉This third edition contains around 25% new and reworked material and has been thoroughly updated to encompass recent advances and future trends. It serves as both an introductory textbook for graduate students as well as a reference resource for telecommunications engineers and researchers.〈p〉〈p〉This edition:〈p〉〈ul〉〈li〉Presents capacity enhancement methods like sectorization, the application of adaptive antennas for Spatial Filtering for Interference Reduction (SFIR) and Space Division Multiple Access (SDMA)〈li〉Provides a detailed introduction to GPRS, HSCSD, and EDGE for packet-switched services and higher data rates〈li〉Features updated coverage on the vastly expanded range of GSM services, including an examination of Multimedia Messaging Service (MMS)〈li〉Adopts a highly graphical approach with numerous illustrations〈/ul〉
    Keywords: Technik / Wissen -- Nachrichtentechnik
    ISBN: 9780470741726
    ISBN: 0470030704
    ISBN: 9780470030707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Communications in Computer and Information Science, Bioinformatics Research and Development: Second International Conference, BIRD 2008 Vienna, Austria, July 7-9, 2008 Proceedings, pp.114-127
    Description: The thermodynamics of RNA-RNA interaction consists of two components: the energy necessary to make a potential binding region accessible, i.e. unpaired, and the energy gained from the base pairing of the two interaction partners. We show here that both components can be efficiently computed using an improved variant of RNAup. The method is then applied to a set of bacterial small RNAs involved in translational control. In all cases of biologically active sRNA target interactions, the target sites predicted by RNAup are in perfect agreement with literature. In addition to prediction of target site location, RNAup can also be used to determine the mode of sRNA action. Using information about target site location and the accessibility change resulting from sRNA binding we can discriminate between positive and negative regulators of translation.
    Keywords: Computer Science ; Computational Biology/Bioinformatics ; Bioinformatics ; Biology ; Computer Science
    ISBN: 9783540705987
    ISBN: 3540705988
    Source: SpringerLink Books
    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