Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.26.3 (RNase III)
1,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sRNA RprA is known to activate rpoS translation in E. coli in an osmolarity-dependent manner. We asked whether RprA stability contributes to osmolarity-dependent regulation and how the RNA binding protein Hfq and the major E. coli endonucleases contribute to this turn-over. The study reveals that osmolarity-dependent turn-over of RprA indeed contributes to its osmolarity-dependent abundance. RprA is stabilized by the RNA chaperone Hfq and in absence of Hfq its turn-over is no longer osmolarity-dependent. The stability of the RprA target mRNA rpoS shows a lower extent of osmolarity dependence, which differs from the profile observed for RprA. Thus, the effect of sucrose is specific for individual RNAs. We can attribute a role of the endoribonuclease RNase E in turn-over of RprA and an indirect effect of the endoribonuclease III in vivo. In addition, RprA is stabilized by the presence of rpoS suggesting that hybrid formation with its target may protect it against ribonucleases. In vitro RprA is cleaved by the RNase E containing degradosome and by RNase III and rpoS interferes with RNase III cleavage. We also show that temperature affects the stabilities of the sRNAs binding to rpoS and of rpoS mRNA itself differentially and that higher stability of DsrA with decreasing temperature may contribute to its high abundance at lower temperatures. This study demonstrates that environmental parameters can affect the stability of sRNAs and consequently their abundance.
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PMID:Turn-over of the small non-coding RNA RprA in E. coli is influenced by osmolarity. 2071 95

RNA turnover plays an important role in both virulence and adaptation to stress in the Gram-positive human pathogen Staphylococcus aureus. However, the molecular players and mechanisms involved in these processes are poorly understood. Here, we explored the functions of S. aureus endoribonuclease III (RNase III), a member of the ubiquitous family of double-strand-specific endoribonucleases. To define genomic transcripts that are bound and processed by RNase III, we performed deep sequencing on cDNA libraries generated from RNAs that were co-immunoprecipitated with wild-type RNase III or two different cleavage-defective mutant variants in vivo. Several newly identified RNase III targets were validated by independent experimental methods. We identified various classes of structured RNAs as RNase III substrates and demonstrated that this enzyme is involved in the maturation of rRNAs and tRNAs, regulates the turnover of mRNAs and non-coding RNAs, and autoregulates its synthesis by cleaving within the coding region of its own mRNA. Moreover, we identified a positive effect of RNase III on protein synthesis based on novel mechanisms. RNase III-mediated cleavage in the 5' untranslated region (5'UTR) enhanced the stability and translation of cspA mRNA, which encodes the major cold-shock protein. Furthermore, RNase III cleaved overlapping 5'UTRs of divergently transcribed genes to generate leaderless mRNAs, which constitutes a novel way to co-regulate neighboring genes. In agreement with recent findings, low abundance antisense RNAs covering 44% of the annotated genes were captured by co-immunoprecipitation with RNase III mutant proteins. Thus, in addition to gene regulation, RNase III is associated with RNA quality control of pervasive transcription. Overall, this study illustrates the complexity of post-transcriptional regulation mediated by RNase III.
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PMID:Global regulatory functions of the Staphylococcus aureus endoribonuclease III in gene expression. 2276 86

Analysis of bacterial transcriptomes have shown the existence of a genome-wide process of overlapping transcription due to the presence of antisense RNAs, as well as mRNAs that overlapped in their entire length or in some portion of the 5'- and 3'-UTR regions. The biological advantages of such overlapping transcription are unclear but may play important regulatory roles at the level of transcription, RNA stability and translation. In a recent report, the human pathogen Staphylococcus aureus is observed to generate genome-wide overlapping transcription in the same bacterial cells leading to a collection of short RNA fragments generated by the endoribonuclease III, RNase III. This processing appears most prominently in Gram-positive bacteria. The implications of both the use of pervasive overlapping transcription and the processing of these double stranded templates into short RNAs are explored and the consequences discussed.
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PMID:An effort to make sense of antisense transcription in bacteria. 2285 76

The endoribonuclease III (RNase III) belongs to the enzyme family known to process double-stranded RNAs. Staphylococcus aureus RNase III was shown to regulate, in concert with the quorum sensing induced RNAIII, the degradation of several mRNAs encoding virulence factors and the transcriptional repressor of toxins Rot. Two of the mRNA-RNAIII complexes involve fully base paired loop-loop interactions with similar sequences that are cleaved by RNase III at a unique position. We show here that the sequence of the base pairs within the loop-loop interaction is not critical for RNase III cleavage, but that the co-axial stacking of three consecutive helices provides an ideal topology for RNase III recognition. In contrast, RNase III induces several strong cleavages in a regular helix, which carries a sequence similar to the loop-loop interaction. The introduction of a bulged loop that interrupts the regular helix restrains the number of cleavages. This work shows that S. aureus RNase III is able to bind and cleave a variety of RNA-mRNA substrates, and that specific structure elements direct the action of RNase III.
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PMID:Loop-loop interactions involved in antisense regulation are processed by the endoribonuclease III in Staphylococcus aureus. 2313 78

Ribonucleases play key roles in gene regulation and in the expression of virulence factors in Staphylococcus aureus. 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 S. aureus. Our approach is based on deep sequencing of cDNA libraries obtained from RNAs isolated by in vivo 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 S. aureus.
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PMID:In vivo mapping of RNA-RNA interactions in Staphylococcus aureus using the endoribonuclease III. 2385 Dec 83

Bacterial cells respond to changes in the environment by adjusting their physiological reactions. In cascades of cellular responses to stresses of various origins, rapid modulation of RNA function is known to be an effective biochemical adaptation. Among many factors affecting RNA function, RNase III, a member of the phylogenetically highly conserved endoribonuclease III family, plays a key role in posttranscriptional regulatory pathways in Escherichia coli. In this review, we provide an overview of the factors affecting RNase III activity in E. coli.
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PMID:Regulation of Escherichia coli RNase III activity. 2622 50

The rRNA genes of Borrelia (Borreliella) burgdorferi are unusually organized; the spirochete has a single 16S rRNA gene that is more than 3 kb from a tandem pair of 23S-5S rRNA operons. We generated an rnc null mutant in B. burgdorferi that exhibits a pleiotropic phenotype, including decreased growth rate and increased cell length. Here, we demonstrate that endoribonuclease III (RNase III) is, as expected, involved in processing the 23S rRNA in B. burgdorferi The 5' and 3' ends of the three rRNAs were determined in the wild type and rnc_Bb mutants; the results suggest that RNase III in B. burgdorferi is required for the full maturation of the 23S rRNA but not for the 5S rRNA nor, curiously, for the 16S rRNA.IMPORTANCE Lyme disease, the most common tick-borne zoonosis in the Northern Hemisphere, is caused by the bacterium Borrelia (Borreliella) burgdorferi, a member of the deeply branching spirochete phylum. B. burgdorferi carries a limited suite of ribonucleases, enzymes that cleave RNA during processing and degradation. Several ribonucleases, including RNase III, are involved in the production of ribosomes, which catalyze translation and are a major target of antibiotics. This is the first study to dissect the role of an RNase in any spirochete. We demonstrate that an RNase III mutant is viable but has altered processing of rRNA.
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PMID:RNase III Processing of rRNA in the Lyme Disease Spirochete Borrelia burgdorferi. 2963 96


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