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Berlin Brandenburg

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  • 1
    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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  • 2
    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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  • 3
    In: EMBO Journal, 13 November 2013, Vol.32(22), pp.2963-2979
    Description: Small RNAs use a diversity of well‐characterized mechanisms to repress mRNAs, but how they activate gene expression at the mRNA level remains not well understood. The predominant activation mechanism of Hfq‐associated small RNAs has been translational control whereby base pairing with the target prevents the formation of an intrinsic inhibitory structure in the mRNA and promotes translation initiation. Here, we report a translation‐independent mechanism whereby the small RNA RydC selectively activates the longer of two isoforms of mRNA (encoding cyclopropane fatty acid synthase) in . Target activation is achieved through seed pairing of the pseudoknot‐exposed, conserved 5′ end of RydC to an upstream region of the mRNA. The seed pairing stabilizes the messenger, likely by interfering directly with RNase E‐mediated decay in the 5′ untranslated region. Intriguingly, this mechanism is generic such that the activation is equally achieved by seed pairing of unrelated small RNAs, suggesting that this mechanism may be utilized in the design of RNA‐controlled synthetic circuits. Physiologically, RydC is the first small RNA known to regulate membrane stability. The small RNA RydC stabilizes target mRNAs in a translation‐independent manner through base pairing to the 5′UTR, blocking RNase E access. Cyclopropane fatty acid synthase is a target for RydC, providing the first link between sRNA regulation and membrane biosynthesis in bacteria.
    Keywords: Fatty Acid Synthesis ; Hfq ; Mrna Activation ; Noncoding Rna ; Small Rna
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 4
    Language: English
    In: Molecular Cell, 04 February 2016, Vol.61(3), pp.352-363
    Description: Small RNAs (sRNAs) from conserved noncoding genes are crucial regulators in bacterial signaling pathways but have remained elusive in the Cpx response to inner membrane stress. Here we report that an alternative biogenesis pathway releasing the conserved mRNA 3′ UTR of stress chaperone CpxP as an ∼60-nt sRNA provides the noncoding arm of the Cpx response. This so-called CpxQ sRNA, generated by general mRNA decay through RNase E, acts as an Hfq-dependent repressor of multiple mRNAs encoding extracytoplasmic proteins. Both CpxQ and the Cpx pathway are required for cell survival under conditions of dissipation of membrane potential. Our discovery of CpxQ illustrates how the conversion of a transcribed 3′ UTR into an sRNA doubles the output of a single mRNA to produce two factors with spatially segregated functions during inner membrane stress: a chaperone that targets problematic proteins in the periplasm and a regulatory RNA that dampens their synthesis in the cytosol. Chao and Vogel discover that a small RNA cleaved off the 3′ end of an mRNA provides the elusive regulatory noncoding arm of the bacterial Cpx response to inner membrane stress.
    Keywords: Cpx Pathway ; Cpxp ; Cpxq ; 3′ Utr ; Hfq ; Rnase E ; Noncoding RNA ; Nhab ; Envelope Stress ; Membrane Potential ; Biology
    ISSN: 1097-2765
    E-ISSN: 1097-4164
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  • 5
    In: EMBO Journal, 02 May 2016, Vol.35(9), pp.991-1011
    Description: The molecular roles of many ‐binding proteins in bacterial post‐transcriptional gene regulation are not well understood. Approaches combining crosslinking with deep sequencing (‐seq) have begun to revolutionize the transcriptome‐wide mapping of eukaryotic ‐binding protein target sites. We have applied ‐seq to chart the target landscape of two major bacterial post‐transcriptional regulators, Hfq and CsrA, in the model pathogen Typhimurium. By detecting binding sites at single‐nucleotide resolution, we identify preferences and structural constraints of Hfq and CsrA during their interactions with hundreds of cellular transcripts. This reveals 3′‐located Rho‐independent terminators as a universal motif involved in Hfq– interactions. Additionally, Hfq preferentially binds 5′ to ‐target sites in s, and 3′ to seed sequences in s, reflecting a simple logic in how Hfq facilitates – interactions. Importantly, global knowledge of Hfq sites significantly improves ‐target predictions. CsrA binds sequences in apical loops and targets many virulence s. Overall, our generic ‐seq approach will bring new insights into post‐transcriptional gene regulation by ‐binding proteins in diverse bacterial species. A new pipeline for ‐seq in maps global –protein interactions and offers a tool for improved understanding of post‐transcriptional control in bacteria. Transcriptome‐wide mapping of Hfq and CsrA target sites by CLIP‐seq. Rho‐independent terminators comprise a general Hfq‐binding motif. Hfq binds 5′ to sRNA‐binding sites in mRNA targets and 3′ to seed sequences in cognate the sRNAs. CsrA preferentially recognizes AUGGA sequences present in loops of hairpin structures. CsrA binds and regulates many mRNAs encoding virulence factors. A new pipeline for CLIP‐seq in maps global RNA–protein interactions and offers a tool for improved understanding of post‐transcriptional control in bacteria.
    Keywords: Clip ; Csra ; Hfq ; Non‐Coding Rna ; Peak Calling ; Post‐Transcriptional Control ; Small Rna ; Terminator ; Translation
    ISSN: 0261-4189
    E-ISSN: 1460-2075
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  • 6
    Language: English
    In: Molecular Cell, 05 January 2017, Vol.65(1), pp.39-51
    Description: Understanding RNA processing and turnover requires knowledge of cleavages by major endoribonucleases within a living cell. We have employed TIER-seq (transiently inactivating an endoribonuclease followed by RNA-seq) to profile cleavage products of the essential endoribonuclease RNase E in . A dominating cleavage signature is the location of a uridine two nucleotides downstream in a single-stranded segment, which we rationalize structurally as a key recognition determinant that may favor RNase E catalysis. Our results suggest a prominent biogenesis pathway for bacterial regulatory small RNAs whereby RNase E acts together with the RNA chaperone Hfq to liberate stable 3′ fragments from various precursor RNAs. Recapitulating this process in vitro, Hfq guides RNase E cleavage of a representative small-RNA precursor for interaction with a mRNA target. In vivo, the processing is required for target regulation. Our findings reveal a general maturation mechanism for a major class of post-transcriptional regulators. Chao et al. discover that the essential bacterial RNase E cleaves numerous transcripts at preferred sites by sensing uridine as a 2-nt ruler. RNase E processing of various precursor RNAs produces many small regulatory RNAs, constituting a major small-RNA biogenesis pathway in bacteria.
    Keywords: Rnase E ; RNA Degradome ; Non-Coding RNA ; Hfq ; 3′ Utr ; Arcz ; Rpra ; Srna Maturation ; Uridine Ruler ; Tier-Seq ; Biology
    ISSN: 1097-2765
    E-ISSN: 1097-4164
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