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Asgari M, Ilbeigikhamsehnejad M, Rismani E, Dinparast Djadid N, Raz A. Molecular characterization of RNase III protein of Asaia sp. for developing a robust RNAi-based paratransgensis tool to affect the sexual life-cycle of Plasmodium or Anopheles fitness. Parasit Vectors 2020; 13:42. [PMID: 31996254 PMCID: PMC6990573 DOI: 10.1186/s13071-020-3889-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 01/04/2020] [Indexed: 01/02/2023] Open
Abstract
Background According to scientific recommendations, paratransgenesis is one of the solutions for improving the effectiveness of the Global Malaria Eradication Programme. In paratransgenesis, symbiont microorganisms are used for distorting or blocking the parasite life-cycle, affecting the fitness and longevity of vectors or reducing the vectorial competence. It has been revealed recently that bacteria could be used as potent tools for double stranded RNA production and delivery to insects. Moreover, findings showed that RNase III mutant bacteria are more competent for this aim. Asaia spp. have been introduced as potent paratransgenesis candidates for combating malaria and, based on their specific features for this goal, could be considered as effective dsRNA production and delivery tools to Anopheles spp. Therefore, we decided to characterize the rnc gene and its related protein to provide the basic required information for creating an RNase III mutant Asaia bacterium. Methods Asaia bacteria were isolated from field-collected Anopheles stephensi mosquitoes. The rnc gene and its surrounding sequences were characterized by rapid amplification of genomic ends. RNase III recombinant protein was expressed in E. coli BL21 and biological activity of the purified recombinant protein was assayed. Furthermore, Asaia RNaseIII amino acid sequence was analyzed by in silico approaches such as homology modeling and docking to determine its structural properties. Results In this study, the structure of rnc gene and its related operon from Asaia sp. was determined. In addition, by performing superimposition and docking with specific substrate, the structural features of Asaia RNaseIII protein such as critical residues which are involved and essential for proper folding of active site, binding of magnesium ions and double stranded RNA molecule to protein and cleaving of dsRNA molecules, were determined. Conclusions In this study, the basic and essential data for creating an RNase III mutant Asaia sp. strain, which is the first step of developing an efficient RNAi-based paratransgenesis tool, were acquired. Asaia sp. have been found in different medically-important vectors and these data are potentially very helpful for researchers studying paratransgenesis and vector-borne diseases and are interested in applying the RNAi technology in the field.
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Affiliation(s)
- Majid Asgari
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - Mahdokht Ilbeigikhamsehnejad
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - Elham Rismani
- Molecular Medicine Department, Pasteur Institute of Iran, Tehran, Iran
| | - Navid Dinparast Djadid
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
| | - Abbasali Raz
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
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2
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The coordinated action of RNase III and RNase G controls enolase expression in response to oxygen availability in Escherichia coli. Sci Rep 2019; 9:17257. [PMID: 31754158 PMCID: PMC6872547 DOI: 10.1038/s41598-019-53883-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/09/2019] [Indexed: 01/25/2023] Open
Abstract
Rapid modulation of RNA function by endoribonucleases during physiological responses to environmental changes is known to be an effective bacterial biochemical adaptation. We report a molecular mechanism underlying the regulation of enolase (eno) expression by two endoribonucleases, RNase G and RNase III, the expression levels of which are modulated by oxygen availability in Escherichia coli. Analyses of transcriptional eno-cat fusion constructs strongly suggested the existence of cis-acting elements in the eno 5' untranslated region that respond to RNase III and RNase G cellular concentrations. Primer extension and S1 nuclease mapping analyses of eno mRNA in vivo identified three eno mRNA transcripts that are generated in a manner dependent on RNase III expression, one of which was found to accumulate in rng-deleted cells. Moreover, our data suggested that RNase III-mediated cleavage of primary eno mRNA transcripts enhanced Eno protein production, a process that involved putative cis-antisense RNA. We found that decreased RNase G protein abundance coincided with enhanced RNase III expression in E. coli grown anaerobically, leading to enhanced eno expression. Thereby, this posttranscriptional up-regulation of eno expression helps E. coli cells adjust their physiological reactions to oxygen-deficient metabolic modes. Our results revealed a molecular network of coordinated endoribonuclease activity that post-transcriptionally modulates the expression of Eno, a key enzyme in glycolysis.
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3
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Song W, Joo M, Yeom JH, Shin E, Lee M, Choi HK, Hwang J, Kim YI, Seo R, Lee JE, Moore CJ, Kim YH, Eyun SI, Hahn Y, Bae J, Lee K. Divergent rRNAs as regulators of gene expression at the ribosome level. Nat Microbiol 2019; 4:515-526. [DOI: 10.1038/s41564-018-0341-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/05/2018] [Indexed: 01/21/2023]
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4
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Abstract
RNA interference (RNAi) is the biological process of mRNA degradation induced by complementary sequences double-stranded (ds) small interfering RNAs (siRNA) and suppression of target gene expression. Exogenous siRNAs (perfectly paired dsRNAs of ∼21–25 nt in length) play an important role in host defense against RNA viruses and in transcriptional and post-transcriptional gene regulation in plants and other eukaryotes. Using RNAi technology by transfecting synthetic siRNAs into eukaryotic cells to silence genes has become an indispensable tool to investigate gene functions, and siRNA-based therapy is being developed to knockdown genes implicated in diseases. Other examples of RNAi technology include method of producing highly potent and purified siRNAs directly from Escherichiacoli cells, based on an unexpected discovery that ectopic expression of p19, a plant viral siRNA-binding protein, stabilizes a cryptic siRNA-like RNA species in bacteria. Those siRNAs, named as pro-siRNA for “prokaryotic siRNA”, are bacterial RNase III products that have chemical and functional properties that like eukaryotic siRNAs.
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5
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Saramago M, Robledo M, Matos RG, Jiménez-Zurdo JI, Arraiano CM. Sinorhizobium meliloti RNase III: Catalytic Features and Impact on Symbiosis. Front Genet 2018; 9:350. [PMID: 30210532 PMCID: PMC6121014 DOI: 10.3389/fgene.2018.00350] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/09/2018] [Indexed: 11/13/2022] Open
Abstract
Members of the ribonuclease (RNase) III family of enzymes are metal-dependent double-strand specific endoribonucleases. They are ubiquitously found and eukaryotic RNase III-like enzymes include Dicer and Drosha, involved in RNA processing and RNA interference. In this work, we have addressed the primary characterization of RNase III from the symbiotic nitrogen-fixing α-proteobacterium Sinorhizobium meliloti. The S. meliloti rnc gene does encode an RNase III-like protein (SmRNase III), with recognizable catalytic and double-stranded RNA (dsRNA)-binding domains that clusters in a branch with its α–proteobacterial counterparts. Purified SmRNase III dimerizes, is active at neutral to alkaline pH and behaves as a strict metal cofactor-dependent double-strand endoribonuclease, with catalytic features distinguishable from those of the prototypical member of the family, the Escherichia coli ortholog (EcRNase III). SmRNase III prefers Mn2+ rather than Mg2+ as metal cofactor, cleaves the generic structured R1.1 substrate at a site atypical for RNase III cleavage, and requires higher cofactor concentrations and longer dsRNA substrates than EcRNase III for optimal activity. Furthermore, the ultraconserved E125 amino acid was shown to play a major role in the metal-dependent catalysis of SmRNase III. SmRNase III degrades endogenous RNA substrates of diverse biogenesis with different efficiency, and is involved in the maturation of the 23S rRNA. SmRNase III loss-of-function neither compromises viability nor alters morphology of S. meliloti cells, but influences growth, nodulation kinetics, the onset of nitrogen fixation and the overall symbiotic efficiency of this bacterium on the roots of its legume host, alfalfa, which ultimately affects plant growth. Our results support an impact of SmRNase III on nodulation and symbiotic nitrogen fixation in plants.
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Affiliation(s)
- Margarida Saramago
- Instituto de Tecnología Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Marta Robledo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Rute G Matos
- Instituto de Tecnología Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - José I Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Cecília M Arraiano
- Instituto de Tecnología Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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6
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Anacker ML, Drecktrah D, LeCoultre RD, Lybecker M, Samuels DS. RNase III Processing of rRNA in the Lyme Disease Spirochete Borrelia burgdorferi. J Bacteriol 2018; 200:e00035-18. [PMID: 29632096 PMCID: PMC5996687 DOI: 10.1128/jb.00035-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/04/2018] [Indexed: 02/08/2023] Open
Abstract
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 rncBb 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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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Borrelia burgdorferi/enzymology
- Borrelia burgdorferi/genetics
- Borrelia burgdorferi/metabolism
- Humans
- Lyme Disease/microbiology
- Operon
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Ribosomal, 5S/metabolism
- Ribonuclease III/genetics
- Ribonuclease III/metabolism
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Affiliation(s)
- Melissa L Anacker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Dan Drecktrah
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Richard D LeCoultre
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Meghan Lybecker
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Department of Biology, University of Colorado, Colorado Springs, Colorado, USA
| | - D Scott Samuels
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, USA
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7
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Gordon GC, Cameron JC, Pfleger BF. Distinct and redundant functions of three homologs of RNase III in the cyanobacterium Synechococcus sp. strain PCC 7002. Nucleic Acids Res 2018; 46:1984-1997. [PMID: 29373746 PMCID: PMC5829567 DOI: 10.1093/nar/gky041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/11/2018] [Accepted: 01/16/2018] [Indexed: 12/19/2022] Open
Abstract
RNase III is a ribonuclease that recognizes and cleaves double-stranded RNA. Across bacteria, RNase III is involved in rRNA maturation, CRISPR RNA maturation, controlling gene expression, and turnover of messenger RNAs. Many organisms have only one RNase III while others have both a full-length RNase III and another version that lacks a double-stranded RNA binding domain (mini-III). The genome of the cyanobacterium Synechococcus sp. strain PCC 7002 (PCC 7002) encodes three homologs of RNase III, two full-length and one mini-III, that are not essential even when deleted in combination. To discern if each enzyme had distinct responsibilities, we collected and sequenced global RNA samples from the wild type strain, the single, double, and triple RNase III mutants. Approximately 20% of genes were differentially expressed in various mutants with some operons and regulons showing complex changes in expression levels between mutants. Two RNase III's had a role in 23S rRNA maturation and the third was involved in copy number regulation one of six native plasmids. In vitro, purified RNase III enzymes were capable of cleaving some of the known Escherichia coli RNase III target sequences, highlighting the remarkably conserved substrate specificity between organisms yet complex regulation of gene expression.
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Affiliation(s)
- Gina C Gordon
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jeffrey C Cameron
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
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8
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RNA Sequencing Identifies New RNase III Cleavage Sites in Escherichia coli and Reveals Increased Regulation of mRNA. mBio 2017; 8:mBio.00128-17. [PMID: 28351917 PMCID: PMC5371410 DOI: 10.1128/mbio.00128-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ribonucleases facilitate rapid turnover of RNA, providing cells with another mechanism to adjust transcript and protein levels in response to environmental conditions. While many examples have been documented, a comprehensive list of RNase targets is not available. To address this knowledge gap, we compared levels of RNA sequencing coverage of Escherichia coli and a corresponding RNase III mutant to expand the list of known RNase III targets. RNase III is a widespread endoribonuclease that binds and cleaves double-stranded RNA in many critical transcripts. RNase III cleavage at novel sites found in aceEF, proP, tnaC, dctA, pheM, sdhC, yhhQ, glpT, aceK, and gluQ accelerated RNA decay, consistent with previously described targets wherein RNase III cleavage initiates rapid degradation of secondary messages by other RNases. In contrast, cleavage at three novel sites in the ahpF, pflB, and yajQ transcripts led to stabilized secondary transcripts. Two other novel sites in hisL and pheM overlapped with transcriptional attenuators that likely serve to ensure turnover of these highly structured RNAs. Many of the new RNase III target sites are located on transcripts encoding metabolic enzymes. For instance, two novel RNase III sites are located within transcripts encoding enzymes near a key metabolic node connecting glycolysis and the tricarboxylic acid (TCA) cycle. Pyruvate dehydrogenase activity was increased in an rnc deletion mutant compared to the wild-type (WT) strain in early stationary phase, confirming the novel link between RNA turnover and regulation of pathway activity. Identification of these novel sites suggests that mRNA turnover may be an underappreciated mode of regulating metabolism. The concerted action and overlapping functions of endoribonucleases, exoribonucleases, and RNA processing enzymes complicate the study of global RNA turnover and recycling of specific transcripts. More information about RNase specificity and activity is needed to make predictions of transcript half-life and to design synthetic transcripts with optimal stability. RNase III does not have a conserved target sequence but instead recognizes RNA secondary structure. Prior to this study, only a few RNase III target sites in E. coli were known, so we used RNA sequencing to provide a more comprehensive list of cleavage sites and to examine the impact of RNase III on transcript degradation. With this added information on how RNase III participates in transcript regulation and recycling, a more complete picture of RNA turnover can be developed for E. coli. Similar approaches could be used to augment our understanding of RNA turnover in other bacteria.
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9
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Nwokeoji AO, Kung AW, Kilby PM, Portwood DE, Dickman MJ. Purification and characterisation of dsRNA using ion pair reverse phase chromatography and mass spectrometry. J Chromatogr A 2016; 1484:14-25. [PMID: 28088361 PMCID: PMC5267946 DOI: 10.1016/j.chroma.2016.12.062] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/14/2016] [Accepted: 12/20/2016] [Indexed: 12/03/2022]
Abstract
rapid purification of dsRNA in a single step protocol. high throughput purification and analysis of a wide range of dsRNAs. developed IP RP HPLC for the rapid, high resolution analysis of the dsRNA. developed a novel method utilising RNase T1 for RNase mass mapping of dsRNA.
RNA interference has provided valuable insight into a wide range of biological systems and is a powerful tool for the analysis of gene function. The exploitation of this pathway to block the expression of specific gene targets holds considerable promise for the development of novel RNAi-based insect management strategies. In addition, there are a wide number of future potential applications of RNAi to control agricultural insect pests as well as its use for prevention of diseases in beneficial insects. The potential to synthesise large quantities of dsRNA by in-vitro transcription or in bacterial systems for RNA interference applications has generated significant demand for the development and application of high throughput analytical tools for the rapid extraction, purification and analysis of dsRNA. Here we have developed analytical methods that enable the rapid purification of dsRNA from associated impurities from bacterial cells in conjunction with downstream analyses. We have optimised TRIzol extractions in conjunction with a single step protocol to remove contaminating DNA and ssRNA, using RNase T1/DNase I digestion under high-salt conditions in combination with solid phase extraction to purify the dsRNA. In addition, we have utilised and developed IP RP HPLC for the rapid, high resolution analysis of the dsRNA. Furthermore, we have optimised base-specific cleavage of dsRNA by RNase A and developed a novel method utilising RNase T1 for RNase mass mapping approaches to further characterise the dsRNA using liquid chromatography interfaced with mass spectrometry.
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Affiliation(s)
- Alison O Nwokeoji
- Department of Chemical and Biological Engineering, ChELSI Institute, Mappin Street, University of Sheffield, S1 3JD, UK
| | - An-Wen Kung
- Department of Chemical and Biological Engineering, ChELSI Institute, Mappin Street, University of Sheffield, S1 3JD, UK
| | - Peter M Kilby
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK
| | - David E Portwood
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, ChELSI Institute, Mappin Street, University of Sheffield, S1 3JD, UK.
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10
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Gone S, Alfonso-Prieto M, Paudyal S, Nicholson AW. Mechanism of Ribonuclease III Catalytic Regulation by Serine Phosphorylation. Sci Rep 2016; 6:25448. [PMID: 27150669 PMCID: PMC4858673 DOI: 10.1038/srep25448] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/15/2016] [Indexed: 12/15/2022] Open
Abstract
Ribonuclease III (RNase III) is a conserved, gene-regulatory bacterial endonuclease that cleaves double-helical structures in diverse coding and noncoding RNAs. RNase III is subject to multiple levels of control, reflective of its global regulatory functions. Escherichia coli (Ec) RNase III catalytic activity is known to increase during bacteriophage T7 infection, reflecting the expression of the phage-encoded protein kinase, T7PK. However, the mechanism of catalytic enhancement is unknown. This study shows that Ec-RNase III is phosphorylated on serine in vitro by purified T7PK, and identifies the targets as Ser33 and Ser34 in the N-terminal catalytic domain. Kinetic experiments reveal a 5-fold increase in kcat and a 1.4-fold decrease in Km following phosphorylation, providing a 7.4–fold increase in catalytic efficiency. Phosphorylation does not change the rate of substrate cleavage under single-turnover conditions, indicating that phosphorylation enhances product release, which also is the rate-limiting step in the steady-state. Molecular dynamics simulations provide a mechanism for facilitated product release, in which the Ser33 phosphomonoester forms a salt bridge with the Arg95 guanidinium group, thereby weakening RNase III engagement of product. The simulations also show why glutamic acid substitution at either serine does not confer enhancement, thus underscoring the specific requirement for a phosphomonoester.
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Affiliation(s)
- Swapna Gone
- Department of Chemistry, Philadelphia PA, 19122, USA
| | | | - Samridhdi Paudyal
- Department of Biology, Temple University, Philadelphia PA, 19122, USA
| | - Allen W Nicholson
- Department of Chemistry, Philadelphia PA, 19122, USA.,Department of Biology, Temple University, Philadelphia PA, 19122, USA
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11
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Abstract
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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12
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Loo J, Wang SS, Peng F, He JA, He L, Guo YC, Gu DY, Kwok HC, Wu SY, Ho HP, Xie WD, Shao YH, Kong SK. A non-PCR SPR platform using RNase H to detect MicroRNA 29a-3p from throat swabs of human subjects with influenza A virus H1N1 infection. Analyst 2015; 140:4566-4575. [PMID: 26000345 DOI: 10.1039/c5an00679a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
As in all RNA viruses, influenza viruses change and mutate constantly because their RNA polymerase has no proofreading ability. This poses a serious threat to public health nowadays. In addition, traditional pathogen-based detection methods may not be able to report an infection from an unknown type or a subtype of virus if its nucleotide sequence is not known. Because of these factors, targeting host microRNA signatures may be an alternative to classify infections and distinguish types of pathogens as microRNAs are produced in humans shortly after infection. Although this approach is in its infant stage, there is an urgent need to develop a rapid reporter assay for microRNA for disease control and prevention. As a proof of concept, we report herein for the first time a non-PCR MARS (MicroRNA-RNase-SPR) assay to detect the microRNA miR-29a-3p from human subjects infected with influenza virus H1N1 by surface plasmon resonance (SPR). In our MARS assay, RNase H is employed to specifically hydrolyze the RNA probes immobilized on the gold surface where they hybridize with its cognate target cDNAs miR-29a-3p, where it was formed from reverse transcription with mature miR-29a-3p specific stem-looped primers. After the digestion of the RNA probe by RNase H, the intact cDNA was released from the RNA-DNA hybrid and bound to a new RNA probe for another enzymatic reaction cycle to amplify signals. With assay optimization, the detection limit of our MARS assay for miR-29a-3p was found to be 1 nM, and this new assay could be completed within 1 hour without thermal cycling. This non-PCR assay with high selectivity for mature microRNA provides a new platform for rapid disease diagnosis, quarantine and disease control.
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Affiliation(s)
- Jacky Loo
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Room 609, Mong Man Wai Building, Shatin, NT, Hong Kong, China.
| | - S S Wang
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - F Peng
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - J A He
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - L He
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - Y C Guo
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - D Y Gu
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518033, China.
| | - H C Kwok
- Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - S Y Wu
- Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - H P Ho
- Center for Advanced Research in Photonics, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - W D Xie
- Shenzhen Key Lab of Health Science and Technology, Division of Life Sciences & Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
| | - Y H Shao
- College of Optoelectronics Engineering, Key Laboratory of Optoelectronic Devices and Systems, Ministry of Education and Guangdong Province, Shenzhen Key Laboratory of Sensor Technology, Shenzhen University, Shenzhen 518060, China
| | - S K Kong
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Room 609, Mong Man Wai Building, Shatin, NT, Hong Kong, China.
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13
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Stability of the osmoregulated promoter-derived proP mRNA is posttranscriptionally regulated by RNase III in Escherichia coli. J Bacteriol 2015; 197:1297-305. [PMID: 25645556 DOI: 10.1128/jb.02460-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The enzymatic activity of Escherichia coli endo-RNase III determines the stability of a subgroup of mRNA species, including bdm, betT, and proU, whose protein products are associated with the cellular response to osmotic stress. Here, we report that the stability of proP mRNA, which encodes a transporter of osmoprotectants, is controlled by RNase III in response to osmotic stress. We observed that steady-state levels of proP mRNA and ProP protein are inversely correlated with cellular RNase III activity and, in turn, affect the proline uptake capacity of the cell. In vitro and in vivo analyses of proP mRNA revealed RNase III cleavage sites in a stem-loop within the 5' untranslated region present only in proP mRNA species synthesized from the osmoregulated P1 promoter. Introduction of nucleotide substitutions in the cleavage site identified inhibited the ribonucleolytic activity of RNase III on proP mRNA, increasing the steady-state levels and half-life of the mRNA. In addition, decreased RNase III activity coincided with a significant increase in both the half-life and abundance of proP mRNA under hyperosmotic stress conditions. Analysis of the RNA bound to RNase III via in vivo cross-linking and immunoprecipitation indicated that this phenomenon is related to the decreased RNA binding capacity of RNase III. Our findings suggest the existence of an RNase III-mediated osmoregulatory network that rapidly balances the expression levels of factors associated with the cellular response to osmotic stress in E. coli. IMPORTANCE Our results demonstrate that RNase III activity on proP mRNA degradation is downregulated in Escherichia coli cells under osmotic stress. In addition, we show that the downregulation of RNase III activity is associated with decreased RNA binding capacity of RNase III under hyperosmotic conditions. In particular, our findings demonstrate a link between osmotic stress and RNase III activity, underscoring the growing importance of posttranscriptional regulation in modulating rapid physiological adjustment to environmental changes.
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Paudyal S, Alfonso-Prieto M, Carnevale V, Redhu SK, Klein ML, Nicholson AW. Combined computational and experimental analysis of a complex of ribonuclease III and the regulatory macrodomain protein, YmdB. Proteins 2015; 83:459-72. [PMID: 25546632 PMCID: PMC4329070 DOI: 10.1002/prot.24751] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 12/04/2014] [Accepted: 12/10/2014] [Indexed: 01/06/2023]
Abstract
Ribonuclease III is a conserved bacterial endonuclease that cleaves double-stranded(ds) structures in diverse coding and noncoding RNAs. RNase III is subject to multiple levels of control that in turn confer global post-transcriptional regulation. The Escherichia coli macrodomain protein YmdB directly interacts with RNase III, and an increase in YmdB amount in vivo correlates with a reduction in RNase III activity. Here, a computational-based structural analysis was performed to identify atomic-level features of the YmdB-RNase III interaction. The docking of monomeric E. coli YmdB with a homology model of the E. coli RNase III homodimer yields a complex that exhibits an interaction of the conserved YmdB residue R40 with specific RNase III residues at the subunit interface. Surface Plasmon Resonance (SPR) analysis provided a KD of 61 nM for the complex, corresponding to a binding free energy (ΔG) of −9.9 kcal/mol. YmdB R40 and RNase III D128 were identified by in silico alanine mutagenesis as thermodynamically important interacting partners. Consistent with the prediction, the YmdB R40A mutation causes a 16-fold increase in KD (ΔΔG = +1.8 kcal/mol), as measured by SPR, and the D128A mutation in both RNase III subunits (D128A/D128′A) causes an 83-fold increase in KD (ΔΔG = +2.7 kcal/mol). The greater effect of the D128A/D128′A mutation may reflect an altered RNase III secondary structure, as revealed by CD spectroscopy, which also may explain the significant reduction in catalytic activity in vitro. The features of the modeled complex relevant to potential RNase III regulatory mechanisms are discussed. Proteins 2015; 83:459–472. © 2014 The Authors. Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Samridhdi Paudyal
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122
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15
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Sim M, Lim B, Sim SH, Kim D, Jung E, Lee Y, Lee K. Two tandem RNase III cleavage sites determine betT mRNA stability in response to osmotic stress in Escherichia coli. PLoS One 2014; 9:e100520. [PMID: 24956275 PMCID: PMC4067347 DOI: 10.1371/journal.pone.0100520] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/28/2014] [Indexed: 11/19/2022] Open
Abstract
While identifying genes regulated by ribonuclease III (RNase III) in Escherichia coli, we observed that steady-state levels of betT mRNA, which encodes a transporter mediating the influx of choline, are dependent on cellular concentrations of RNase III. In the present study, we also observed that steady-state levels of betT mRNA are dependent on RNase III activity upon exposure to osmotic stress, indicating the presence of cis-acting elements controlled by RNase III in betT mRNA. Primer extension analyses of betT mRNA revealed two tandem RNase III cleavage sites in its stem-loop region, which were biochemically confirmed via in vitro cleavage assays. Analyses of cleavage sites suggested the stochastic selection of cleavage sites by RNase III, and mutational analyses indicated that RNase III cleavage at either site individually is insufficient for efficient betT mRNA degradation. In addition, both the half-life and abundance of betT mRNA were significantly increased in association with decreased RNase III activity under hyper-osmotic stress conditions. Our findings demonstrate that betT mRNA stability is controlled by RNase III at the post-transcriptional level under conditions of osmotic stress.
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Affiliation(s)
- Minji Sim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Boram Lim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Se-Hoon Sim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Daeyoung Kim
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Euihan Jung
- Department of Chemistry, KAIST, Daejeon, Republic of Korea
| | - Younghoon Lee
- Department of Chemistry, KAIST, Daejeon, Republic of Korea
| | - Kangseok Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
- * E-mail:
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16
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Song W, Kim YH, Sim SH, Hwang S, Lee JH, Lee Y, Bae J, Hwang J, Lee K. Antibiotic stress-induced modulation of the endoribonucleolytic activity of RNase III and RNase G confers resistance to aminoglycoside antibiotics in Escherichia coli. Nucleic Acids Res 2014; 42:4669-81. [PMID: 24489121 PMCID: PMC3985665 DOI: 10.1093/nar/gku093] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Here, we report a resistance mechanism that is induced through the modulation of 16S ribosomal RNA (rRNA) processing on the exposure of Escherichia coli cells to aminoglycoside antibiotics. We observed decreased expression levels of RNase G associated with increased RNase III activity on rng mRNA in a subgroup of E. coli isolates that transiently acquired resistance to low levels of kanamycin or streptomycin. Analyses of 16S rRNA from the aminoglycoside-resistant E. coli cells, in addition to mutagenesis studies, demonstrated that the accumulation of 16S rRNA precursors containing 3–8 extra nucleotides at the 5’ terminus, which results from incomplete processing by RNase G, is responsible for the observed aminoglycoside resistance. Chemical protection, mass spectrometry analysis and cell-free translation assays revealed that the ribosomes from rng-deleted E. coli have decreased binding capacity for, and diminished sensitivity to, streptomycin and neomycin, compared with wild-type cells. It was observed that the deletion of rng had similar effects in Salmonella enterica serovar Typhimurium strain SL1344. Our findings suggest that modulation of the endoribonucleolytic activity of RNase III and RNase G constitutes a previously uncharacterized regulatory pathway for adaptive resistance in E. coli and related gram-negative bacteria to aminoglycoside antibiotics.
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Affiliation(s)
- Wooseok Song
- Department of Life Science, Chung-Ang University, Seoul 156-756, Republic of Korea, Marine Biotechnology Research Division, Korea Institute of Ocean Science and Technology, Ansan 426-744, Republic of Korea, Department of Microbiology, Catholic University of Daegu, School of Medicine, Nam-Gu, Daegu 705-718, Republic of Korea, Department of Chemistry, KAIST, Daejeon 305-701, Republic of Korea, Department of Pharmacy, Chung-Ang University, Seoul 156-756, Republic of Korea and Department of Microbiology, Pusan National University, Busan 609-735, Republic of Korea
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17
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Ruiz de los Mozos I, Vergara-Irigaray M, Segura V, Villanueva M, Bitarte N, Saramago M, Domingues S, Arraiano CM, Fechter P, Romby P, Valle J, Solano C, Lasa I, Toledo-Arana A. Base pairing interaction between 5'- and 3'-UTRs controls icaR mRNA translation in Staphylococcus aureus. PLoS Genet 2013; 9:e1004001. [PMID: 24367275 PMCID: PMC3868564 DOI: 10.1371/journal.pgen.1004001] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/20/2013] [Indexed: 11/18/2022] Open
Abstract
The presence of regulatory sequences in the 3′ untranslated region (3′-UTR) of eukaryotic mRNAs controlling RNA stability and translation efficiency is widely recognized. In contrast, the relevance of 3′-UTRs in bacterial mRNA functionality has been disregarded. Here, we report evidences showing that around one-third of the mapped mRNAs of the major human pathogen Staphylococcus aureus carry 3′-UTRs longer than 100-nt and thus, potential regulatory functions. We selected the long 3′-UTR of icaR, which codes for the repressor of the main exopolysaccharidic compound of the S. aureus biofilm matrix, to evaluate the role that 3′-UTRs may play in controlling mRNA expression. We showed that base pairing between the 3′-UTR and the Shine-Dalgarno (SD) region of icaR mRNA interferes with the translation initiation complex and generates a double-stranded substrate for RNase III. Deletion or substitution of the motif (UCCCCUG) within icaR 3′-UTR was sufficient to abolish this interaction and resulted in the accumulation of IcaR repressor and inhibition of biofilm development. Our findings provide a singular example of a new potential post-transcriptional regulatory mechanism to modulate bacterial gene expression through the interaction of a 3′-UTR with the 5′-UTR of the same mRNA. At both sides of the protein-coding region, the mRNA molecule contains sequences that are not translated to protein. In eukaryotes, the untranslated 3′ region (3′-UTR), which comprises from the last codon used in translation to the 3′ end of the mRNA, controls mRNA stability, location and translation efficiency. In contrast, knowledge about the functions of 3′-UTRs in bacterial physiology is scarce. Here, we demonstrate that bacterial 3′-UTRs might play regulatory functions that might resemble those already described in eukaryotes. Transcriptome analysis of the human pathogen Staphylococcus aureus revealed that at least 30% of mRNAs contain long 3′-UTRs. Using the 3′-UTR of the mRNA encoding the main biofilm repressor IcaR as a model, we show that the 3′-UTR interferes with the translation initiation complex and promotes mRNA decay through base pairing with the ribosome binding site. This event contributes to adjusting IcaR level and modulating exopolysaccharide production and biofilm development in S. aureus. Our data illustrate that bacterial 3′-UTRs can provide strategies for fine-tuning control of gene expression.
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Affiliation(s)
- Igor Ruiz de los Mozos
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Marta Vergara-Irigaray
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Victor Segura
- Genomics, Proteomics and Bioinformatics Unit. Center for Applied Medical Research. University of Navarra. Pamplona, Spain
| | - Maite Villanueva
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Nerea Bitarte
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Margarida Saramago
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa. Oeiras, Portugal
| | - Susana Domingues
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa. Oeiras, Portugal
| | - Cecilia M. Arraiano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa. Oeiras, Portugal
| | - Pierre Fechter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC. Strasbourg, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC. Strasbourg, France
| | - Jaione Valle
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Cristina Solano
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
| | - Iñigo Lasa
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
- * E-mail: (IL); (ATA)
| | - Alejandro Toledo-Arana
- Laboratory of Microbial Biofilms. Instituto de Agrobiotecnología (IDAB). Universidad Pública de Navarra-CSIC-Gobierno de Navarra. Campus de Arrosadía. Pamplona, Spain
- * E-mail: (IL); (ATA)
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Lim B, Ahn S, Sim M, Lee K. RNase III controls mltD mRNA degradation in Escherichia coli. Curr Microbiol 2013; 68:518-23. [PMID: 24343175 DOI: 10.1007/s00284-013-0504-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 10/24/2013] [Indexed: 11/26/2022]
Abstract
RNase III is a double-stranded RNA-specific endoribonuclease that processes and degrades numerous mRNA molecules in Escherichia coli. A previous genome-wide analysis of E. coli transcripts showed that steady-state levels of mltD mRNA, which encodes membrane-bound lytic murein transglycosylase D, was most affected by changes in cellular concentration of RNase III. Consistent with this observation, in vitro and in vivo analyses of mltD mRNA revealed RNase III cleavage sites in the coding region of mltD mRNA. Introduction of a nucleotide substitution at the identified RNase III cleavage sites inhibited RNase III cleavage activity on mltD mRNA, resulting in, consequently, approximately two-fold increase in the steady-state level of the mRNA. These findings reveal an RNase III-mediated regulatory pathway that modulates mltD expression in E. coli.
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Affiliation(s)
- Boram Lim
- Department of Life Science, Chung-Ang University, 84 Heuksok-Ro, Dongjak-Gu, Seoul, 156-756, Republic of Korea
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19
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Abstract
Campylobacter jejuni is a foodborne bacterial pathogen, which is now considered as a leading cause of human bacterial gastroenteritis. The information regarding ribonucleases in C. jejuni is very scarce but there are hints that they can be instrumental in virulence mechanisms. Namely, PNPase (polynucleotide phosphorylase) was shown to allow survival of C. jejuni in refrigerated conditions, to facilitate bacterial swimming, cell adhesion, colonization and invasion. In several microorganisms PNPase synthesis is auto-controlled in an RNase III (ribonuclease III)-dependent mechanism. Thereby, we have cloned, overexpressed, purified and characterized Cj-RNase III (C. jejuni RNase III). We have demonstrated that Cj-RNase III is able to complement an Escherichia coli rnc-deficient strain in 30S rRNA processing and PNPase regulation. Cj-RNase III was shown to be active in an unexpectedly large range of conditions, and Mn2+ seems to be its preferred co-factor, contrarily to what was described for other RNase III orthologues. The results lead us to speculate that Cj-RNase III may have an important role under a Mn2+-rich environment. Mutational analysis strengthened the function of some residues in the catalytic mechanism of action of RNase III, which was shown to be conserved.
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20
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Functional conservation of RNase III-like enzymes: studies on a Vibrio vulnificus ortholog of Escherichia coli RNase III. Curr Microbiol 2013; 68:413-8. [PMID: 24241331 DOI: 10.1007/s00284-013-0492-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
Abstract
Bacterial ribonuclease III (RNase III) belongs to the RNase III enzyme family, which plays a pivotal role in controlling mRNA stability and RNA processing in both prokaryotes and eukaryotes. In the Vibrio vulnificus genome, one open reading frame encodes a protein homologous to E. coli RNase III, designated Vv-RNase III, which has 77.9 % amino acid identity to E. coli RNase III. Here, we report that Vv-RNase III has the same cleavage specificity as E. coli RNase III in vivo and in vitro. Expressing Vv-RNase III in E. coli cells deleted for the RNase III gene (rnc) restored normal rRNA processing and, consequently, growth rates of these cells comparable to wild-type cells. In vitro cleavage assays further showed that Vv-RNase III has the same cleavage activity and specificity as E. coli RNase III on RNase III-targeted sequences of corA and mltD mRNA. Our findings suggest that RNase III-like proteins have conserved cleavage specificity across bacterial species.
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21
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Lee JM, Kojin Y, Tatsuke T, Mon H, Miyagawa Y, Kusakabe T. Coexpression of Escherichia coli RNase III in silkworm cells improves the efficiency of RNA interference induced by long hairpin dsRNAs. INSECT SCIENCE 2013; 20:69-77. [PMID: 23955827 DOI: 10.1111/j.1744-7917.2012.01569.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Long hairpin dsRNA transcribed from chromosomal DNA can induce RNA interference in Bombyx mori cells, although its gene silencing efficiency is lower than that of exogenously introduced double-stranded RNAs (dsRNAs). To solve this problem, we monitored the nuclear cytoplasmic translocation of the transcribed hairpin dsRNA and analyzed the processing efficiency into mature small interfering RNA (siRNA). Northern blot analysis revealed that the transcribed hairpin dsRNAs were spliced and transported into the cytoplasm, but were not effectively diced into siRNAs. Interestingly, RNAi with hairpin dsRNAs from genome-integrated IR transgene was stimulated by the coexpression of Escherichia coli RNase III, although this exogenous enzyme seemed to bring about nonspecific cleavage of cellular mRNA.
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Affiliation(s)
- Jae Man Lee
- Laboratory of Silkworm Sciences, Kyushu University Graduate School of Bioresource and Bioenvironmental Sciences, Fukuoka, Japan
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22
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Small RNA modules confer different stabilities and interact differently with multiple targets. PLoS One 2013; 8:e52866. [PMID: 23349691 PMCID: PMC3551931 DOI: 10.1371/journal.pone.0052866] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 11/22/2012] [Indexed: 01/08/2023] Open
Abstract
Bacterial Hfq-associated small regulatory RNAs (sRNAs) parallel animal microRNAs in their ability to control multiple target mRNAs. The small non-coding MicA RNA represses the expression of several genes, including major outer membrane proteins such as ompA, tsx and ecnB. In this study, we have characterised the RNA determinants involved in the stability of MicA and analysed how they influence the expression of its targets. Site-directed mutagenesis was used to construct MicA mutated forms. The 5′linear domain, the structured region with two stem-loops, the A/U-rich sequence or the 3′ poly(U) tail were altered without affecting the overall secondary structure of MicA. The stability and the target regulation abilities of the wild-type and the different mutated forms of MicA were then compared. The 5′ domain impacted MicA stability through an RNase III-mediated pathway. The two stem-loops showed different roles and disruption of stem-loop 2 was the one that mostly affected MicA stability and abundance. Moreover, STEM2 was found to be more important for the in vivo repression of both ompA and ecnB mRNAs while STEM1 was critical for regulation of tsx mRNA levels. The A/U-rich linear sequence is not the only Hfq-binding site present in MicA and the 3′ poly(U) sequence was critical for sRNA stability. PNPase was shown to be an important exoribonuclease involved in sRNA degradation. In addition to the 5′ domain of MicA, the stem-loops and the 3′ poly(U) tail are also shown to affect target-binding. Disruption of the 3′U-rich sequence greatly affects all targets analysed. In conclusion, our results have shown that it is important to understand the “sRNA anatomy” in order to modulate its stability. Furthermore, we have demonstrated that MicA RNA can use different modules to regulate its targets. This knowledge can allow for the engineering of non-coding RNAs that interact differently with multiple targets.
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Gone S, Nicholson AW. Bacteriophage T7 protein kinase: Site of inhibitory autophosphorylation, and use of dephosphorylated enzyme for efficient modification of protein in vitro. Protein Expr Purif 2012; 85:218-23. [PMID: 22951189 DOI: 10.1016/j.pep.2012.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/12/2012] [Accepted: 08/13/2012] [Indexed: 12/01/2022]
Abstract
Bacteriophage T7 encodes a serine/threonine-specific protein kinase that phosphorylates multiple cellular proteins during infection of Escherichia coli. Recombinant T7 protein kinase (T7PK), normally purified in phosphorylated form, exhibits a modest level of phosphotransferase activity. A procedure is described that provides dephosphorylated T7PK with an enhanced ability to phosphorylate protein substrates, including translation initiation factor IF1 and the nuclease domain of ribonuclease III. Mass spectrometric analysis identified Thr12 as the site of IF1 phosphorylation in vitro. T7PK undergoes Mg(2+)-dependent autophosphorylation on Ser216 in vitro, which also is modified in vivo. The inability to isolate the presumptive autophosphorylation-resistant T7PK Ser216Ala mutant indicates a toxicity of the phosphotransferase activity and suggests a role for Ser216 modification in limiting T7PK activity during infection.
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Affiliation(s)
- Swapna Gone
- Department of Chemistry, Temple University, 1901 North 13th St., Philadelphia, PA 19122, USA
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24
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Lioliou E, Sharma CM, Caldelari I, Helfer AC, Fechter P, Vandenesch F, Vogel J, Romby P. Global regulatory functions of the Staphylococcus aureus endoribonuclease III in gene expression. PLoS Genet 2012; 8:e1002782. [PMID: 22761586 PMCID: PMC3386247 DOI: 10.1371/journal.pgen.1002782] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 05/09/2012] [Indexed: 11/18/2022] Open
Abstract
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. Control of mRNA stability is crucial for bacteria to survive and rapidly adapt to environmental changes and stress conditions. The molecular players and the degradation pathways involved in these adaptive processes are poorly understood in Staphylococcus aureus. The universally conserved double-strand-specific endoribonuclease III (RNase III) in S. aureus is known to repress the synthesis of several virulence factors and was recently implicated in genome-wide mRNA processing mediated by antisense transcripts. We present here the first global map of direct RNase III targets in S. aureus. Deep sequencing was used to identify RNAs associated with epitope-tagged wild-type RNase III and two catalytically impaired but binding-competent mutant proteins in vivo. Experimental validation revealed an unexpected variety of structured RNA transcripts as novel RNase III substrates. In addition to rRNA operon maturation, autoregulation, degradation of structured RNAs, and antisense regulation, we propose novel mechanisms by which RNase III increases mRNA translation. Overall, this study shows that RNase III has a broad function in gene regulation of S. aureus. We can now address more specifically the roles of this universally conserved enzyme in gene regulation in response to stress and during host infection.
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Affiliation(s)
- Efthimia Lioliou
- Architecture et Réactivité de l′ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | | | - Isabelle Caldelari
- Architecture et Réactivité de l′ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Anne-Catherine Helfer
- Architecture et Réactivité de l′ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Pierre Fechter
- Architecture et Réactivité de l′ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - François Vandenesch
- Inserm U851, Centre National de Référence des Staphylocoques, Université de Lyon, Lyon, France
| | - Jörg Vogel
- Institut für Molekulare Infektionsbiologie, Würzburg, Germany
- * E-mail: (JV); (PR)
| | - Pascale Romby
- Architecture et Réactivité de l′ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
- * E-mail: (JV); (PR)
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Zhang ZX, Min WP, Jevnikar AM. Use of RNA interference to minimize ischemia reperfusion injury. Transplant Rev (Orlando) 2012; 26:140-55. [DOI: 10.1016/j.trre.2011.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 03/22/2011] [Indexed: 12/21/2022]
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26
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Abstract
In Escherichia coli, the corA gene encodes a transporter that mediates the influx of Co(2+), Mg(2+), and Ni(2+) into the cell. During the course of experiments aimed at identifying RNase III-dependent genes in E. coli, we observed that steady-state levels of corA mRNA as well as the degree of cobalt influx into the cell were dependent on cellular concentrations of RNase III. In addition, changes in corA expression levels by different cellular concentrations of RNase III were closely correlated with degrees of resistance of E. coli cells to Co(2+) and Ni(2+). In vitro and in vivo cleavage analyses of corA mRNA identified RNase III cleavage sites in the 5'-untranslated region of the corA mRNA. The introduction of nucleotide substitutions at the identified RNase III cleavage sites abolished RNase III cleavage activity on corA mRNA and resulted in prolonged half-lives of the mRNA, which demonstrates that RNase III cleavage constitutes a rate-determining step for corA mRNA degradation. These findings reveal an RNase III-mediated regulatory pathway that functions to modulate corA expression and, in turn, the influx of metal ions transported by CorA in E. coli.
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Kiyota E, Okada R, Kondo N, Hiraguri A, Moriyama H, Fukuhara T. An Arabidopsis RNase III-like protein, AtRTL2, cleaves double-stranded RNA in vitro. JOURNAL OF PLANT RESEARCH 2011; 124:405-14. [PMID: 20978817 DOI: 10.1007/s10265-010-0382-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2010] [Accepted: 09/16/2010] [Indexed: 05/30/2023]
Abstract
Class 1 ribonuclease III (RNase III), found in bacteria and yeast, is involved in processing functional RNA molecules such as ribosomal RNAs (rRNAs). However, in Arabidopsis thaliana, the lack of an obvious phenotype or quantitative change in mature rRNAs in class 1 RNase III (AtRTL2) mutants and overexpressing plants suggests that AtRTL2 is not involved in rRNA maturation. We characterized the in vitro activity of AtRTL2 to consider its in vivo function. AtRTL2 cleaved double-stranded RNA (dsRNA) specifically in vitro, yielding products of approximately 25 nt or longer in length, in contrast to 10-20 nt long products in bacteria and yeasts. Although dsRNA-binding activity was not detected, the dsRNA-binding domains in AtRTL2 were essential for its dsRNA-cleaving activity. Accumulation of small RNAs derived from transgene dsRNAs was increased when AtRTL2 was transiently expressed in Nicotiana benthamiana leaves by agroinfiltration. These results raise the possibility that AtRTL2 has functions distinct from those of other class 1 RNase IIIs in vivo.
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Affiliation(s)
- Eri Kiyota
- Department of Applied Biological Sciences, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan
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Agüero-Chapin G, de la Riva GA, Molina-Ruiz R, Sánchez-Rodríguez A, Pérez-Machado G, Vasconcelos V, Antunes A. Non-linear models based on simple topological indices to identify RNase III protein members. J Theor Biol 2010; 273:167-78. [PMID: 21192951 DOI: 10.1016/j.jtbi.2010.12.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 11/15/2010] [Accepted: 12/13/2010] [Indexed: 01/27/2023]
Abstract
Alignment-free classifiers are especially useful in the functional classification of protein classes with variable homology and different domain structures. Thus, the Topological Indices to BioPolymers (TI2BioP) methodology (Agüero-Chapin et al., 2010) inspired in both the TOPS-MODE and the MARCH-INSIDE methodologies allows the calculation of simple topological indices (TIs) as alignment-free classifiers. These indices were derived from the clustering of the amino acids into four classes of hydrophobicity and polarity revealing higher sequence-order information beyond the amino acid composition level. The predictability power of such TIs was evaluated for the first time on the RNase III family, due to the high diversity of its members (primary sequence and domain organization). Three non-linear models were developed for RNase III class prediction: Decision Tree Model (DTM), Artificial Neural Networks (ANN)-model and Hidden Markov Model (HMM). The first two are alignment-free approaches, using TIs as input predictors. Their performances were compared with a non-classical HMM, modified according to our amino acid clustering strategy. The alignment-free models showed similar performances on the training and the test sets reaching values above 90% in the overall classification. The non-classical HMM showed the highest rate in the classification with values above 95% in training and 100% in test. Although the higher accuracy of the HMM, the DTM showed simplicity for the RNase III classification with low computational cost. Such simplicity was evaluated in respect to HMM and ANN models for the functional annotation of a new bacterial RNase III class member, isolated and annotated by our group.
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Affiliation(s)
- Guillermin Agüero-Chapin
- CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 177, 4050-123 Porto, Portugal
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29
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Shi Z, Nicholson RH, Jaggi R, Nicholson AW. Characterization of Aquifex aeolicus ribonuclease III and the reactivity epitopes of its pre-ribosomal RNA substrates. Nucleic Acids Res 2010; 39:2756-68. [PMID: 21138964 PMCID: PMC3074117 DOI: 10.1093/nar/gkq1030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ribonuclease III cleaves double-stranded (ds) structures in bacterial RNAs and participates in diverse RNA maturation and decay pathways. Essential insight on the RNase III mechanism of dsRNA cleavage has been provided by crystallographic studies of the enzyme from the hyperthermophilic bacterium, Aquifex aeolicus. However, the biochemical properties of A. aeolicus (Aa)-RNase III and the reactivity epitopes of its substrates are not known. The catalytic activity of purified recombinant Aa-RNase III exhibits a temperature optimum of ∼70–85°C, with either Mg2+ or Mn2+ supporting efficient catalysis. Small hairpins based on the stem structures associated with the Aquifex 16S and 23S rRNA precursors are cleaved at sites that are consistent with production of the immediate precursors to the mature rRNAs. Substrate reactivity is independent of the distal box sequence, but is strongly dependent on the proximal box sequence. Structural studies have shown that a conserved glutamine (Q157) in the Aa-RNase III dsRNA-binding domain (dsRBD) directly interacts with a proximal box base pair. Aa-RNase III cleavage of the pre-16S substrate is blocked by the Q157A mutation, which reflects a loss of substrate binding affinity. Thus, a highly conserved dsRBD-substrate interaction plays an important role in substrate recognition by bacterial RNase III.
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MESH Headings
- Amino Acid Sequence
- Bacteria/enzymology
- Base Pairing
- Base Sequence
- Biocatalysis
- Cations, Divalent/chemistry
- Enzyme Stability
- Glutamine/chemistry
- Hydrogen-Ion Concentration
- Molecular Sequence Data
- RNA Precursors/chemistry
- RNA Precursors/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Double-Stranded/metabolism
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/metabolism
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/metabolism
- Ribonuclease III/chemistry
- Ribonuclease III/metabolism
- Salts/chemistry
- Temperature
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Affiliation(s)
- Zhongjie Shi
- Department of Chemistry and Department of Biology, Temple University, Philadelphia, PA, USA
| | - Rhonda H. Nicholson
- Department of Chemistry and Department of Biology, Temple University, Philadelphia, PA, USA
| | - Ritu Jaggi
- Department of Chemistry and Department of Biology, Temple University, Philadelphia, PA, USA
| | - Allen W. Nicholson
- Department of Chemistry and Department of Biology, Temple University, Philadelphia, PA, USA
- *To whom correspondence should be addressed. Tel: +1 215 204 9048; Fax: +1 215 204 1532;
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30
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Viegas SC, Silva IJ, Saramago M, Domingues S, Arraiano CM. Regulation of the small regulatory RNA MicA by ribonuclease III: a target-dependent pathway. Nucleic Acids Res 2010; 39:2918-30. [PMID: 21138960 PMCID: PMC3074148 DOI: 10.1093/nar/gkq1239] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MicA is a trans-encoded small non-coding RNA, which downregulates porin-expression in stationary-phase. In this work, we focus on the role of endoribonucleases III and E on Salmonella typhimurium sRNA MicA regulation. RNase III is shown to regulate MicA in a target-coupled way, while RNase E is responsible for the control of free MicA levels in the cell. We purified both Salmonella enzymes and demonstrated that in vitro RNase III is only active over MicA when in complex with its targets (whether ompA or lamB mRNAs). In vivo, MicA is demonstrated to be cleaved by RNase III in a coupled way with ompA mRNA. On the other hand, RNase E is able to cleave unpaired MicA and does not show a marked dependence on its 5′ phosphorylation state. The main conclusion of this work is the existence of two independent pathways for MicA turnover. Each pathway involves a distinct endoribonuclease, having a different role in the context of the fine-tuned regulation of porin levels. Cleavage of MicA by RNase III in a target-dependent fashion, with the concomitant decay of the mRNA target, strongly resembles the eukaryotic RNAi system, where RNase III-like enzymes play a pivotal role.
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Affiliation(s)
- Sandra C Viegas
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal
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31
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Nathania L, Nicholson AW. Thermotoga maritima ribonuclease III. Characterization of thermostable biochemical behavior and analysis of conserved base pairs that function as reactivity epitopes for the Thermotoga 23S rRNA precursor. Biochemistry 2010; 49:7164-78. [PMID: 20677811 DOI: 10.1021/bi100930u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cleavage of double-stranded (ds) RNA by ribonuclease III is a conserved early step in bacterial rRNA maturation. Studies on the mechanism of dsRNA cleavage by RNase III have focused mainly on the enzymes from mesophiles such as Escherichia coli. In contrast, neither the catalytic properties of extremophile RNases III nor the structures and reactivities of their cognate substrates have been described. The biochemical behavior of RNase III of the hyperthermophilic bacterium Thermotoga maritima was analyzed using purified recombinant enzyme. T. maritima (Tm) RNase III catalytic activity exhibits a broad optimal temperature range of approximately 40-70 degrees C, with significant activity at 95 degrees C. Tm-RNase III cleavage of substrate is optimally supported by Mg(2+) at >or=1 mM concentrations. Mn(2+), Co(2+), and Ni(2+) also support activity but with reduced efficiencies. The enzyme functions optimally at pH 8 and approximately 50-80 mM salt concentrations. Small RNA hairpins that incorporate the 16S and 23S pre-rRNA stem sequences are efficiently cleaved by Tm-RNase III at sites that are consistent with production in vivo of the immediate precursors to the mature rRNAs. Analysis of pre-23S substrate variants reveals a dependence of reactivity on the base-pair (bp) sequence in the proximal box (pb), a site of protein contact that functions as a positive recognition determinant for Escherichia coli (Ec) RNase III substrates. The dependence of reactivity on the pb sequence is similar to that observed with Ec-RNase III substrates. In fact, Tm-RNase III cleaves an Ec-RNase III substrate with identical specificity and is inhibited by antideterminant bp that also inhibit Ec-RNase III. These results indicate the conservation, across a broad phylogenetic distance, of positive and negative determinants of reactivity of bacterial RNase III substrates.
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Affiliation(s)
- Lilian Nathania
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, USA
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32
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Sim SH, Yeom JH, Shin C, Song WS, Shin E, Kim HM, Cha CJ, Han SH, Ha NC, Kim SW, Hahn Y, Bae J, Lee K. Escherichia coli ribonuclease III activity is downregulated by osmotic stress: consequences for the degradation of bdm mRNA in biofilm formation. Mol Microbiol 2009; 75:413-25. [PMID: 19943899 DOI: 10.1111/j.1365-2958.2009.06986.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
During the course of experiments aimed at identifying genes with ribonuclease III (RNase III)-dependent expression in Escherichia coli, we found that steady state levels of bdm mRNA were dependent on cellular concentrations of RNase III. The half-lives of adventitiously overexpressed bdm mRNA and the activities of a transcriptional bdm'-'cat fusion were observed to be dependent on cellular concentrations of RNase III, indicating the existence of cis-acting elements in bdm mRNA responsive to RNase III. In vitro and in vivo cleavage analyses of bdm mRNA identified two RNase III cleavage motifs, one in the 5'-untranslated region and the other in the coding region of bdm mRNA, and indicated that RNase III cleavages in the coding region constitute a rate-determining step for bdm mRNA degradation. We also discovered that downregulation of the ribonucleolytic activity of RNase III is required for the sustained elevation of RcsB-induced bdm mRNA levels during osmotic stress and that cells overexpressing bdm form biofilms more efficiently. These findings indicate that the Rcs signalling system has an additional regulatory pathway that functions to modulate bdm expression and consequently, adapt E. coli cells to osmotic stress.
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Affiliation(s)
- Se-Hoon Sim
- Department of Life Science (BK21 program), Chung-Ang University, Seoul, Republic of Korea
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33
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Yin G, Sun Z, Liu N, Zhang L, Song Y, Zhu C, Wen F. Production of double-stranded RNA for interference with TMV infection utilizing a bacterial prokaryotic expression system. Appl Microbiol Biotechnol 2009; 84:323-33. [PMID: 19330324 DOI: 10.1007/s00253-009-1967-y] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 02/11/2009] [Accepted: 03/14/2009] [Indexed: 10/21/2022]
Abstract
In many species, the introduction of double-stranded RNA (dsRNA) induces potent and specific gene silencing, a phenomenon called RNA interference (RNAi). RNAi is the process of sequence-specific, posttranscriptional gene silencing (PTGS) in animals and plants, mediated by dsRNA homologous to the silenced genes. In plants, PTGS is part of a defense mechanism against virus infection, and dsRNA is the pivotal factor that induces gene silencing. Here, we report an efficient method that can produce dsRNA using a bacterial prokaryotic expression system. Using the bacteriophage lambda-dependent Red recombination system, we knocked out the rnc genes of two different Escherichia coli strains and constructed three different vectors that could produce dsRNAs. This work explores the best vector/host combinations for high output of dsRNA. In the end, we found that strain M-JM109 or the M-JM109lacY mutant strain and the vector pGEM-CP480 are the best choices for producing great quantities of dsRNA. Resistance analyses and Northern blot showed that Tobacco mosaic virus infection could be inhibited by dsRNA, and the resistance was an RNA-mediated virus resistance. Our findings indicate that exogenous dsRNA could form the basis for an effective and environmentally friendly biotechnological tool that protects plants from virus infections.
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Affiliation(s)
- Guohua Yin
- College of Plant Protection, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong, 271018, China
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34
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Meng W, Nicholson RH, Nathania L, Pertzev AV, Nicholson AW. New approaches to understanding double-stranded RNA processing by ribonuclease III purification and assays of homodimeric and heterodimeric forms of RNase III from bacterial extremophiles and mesophiles. Methods Enzymol 2009; 447:119-29. [PMID: 19161841 DOI: 10.1016/s0076-6879(08)02207-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Ribonuclease III (RNase III) is a double-stranded (ds)-RNA-specific endonuclease that plays essential roles in the maturation and decay of coding and noncoding RNAs. Bacterial RNases III are structurally the simplest members of the RNase III family, which includes the eukaryotic orthologs Dicer and Drosha. High-resolution crystal structures of RNase III of the hyperthermophilic bacteria Aquifex aeolicus and Thermotoga maritima are available. A. aeolicus RNase III also has been cocrystallized with dsRNA or specific hairpin substrates. These structures have provided essential structural insight to the mechanism of dsRNA recognition and cleavage. However, comparatively little is known about the catalytic behaviors of A. aeolicus or T. maritima RNases III. This chapter provides protocols for the purification of A. aeolicus and T. maritima RNases III and also describes the preparation of artificial heterodimers of Escherichia coli RNase III, which are providing new insight on the subunit and domain interactions involved in dsRNA recognition and cleavage.
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Affiliation(s)
- Wenzhao Meng
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania, USA
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35
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Kim KS, Manasherob R, Cohen SN. YmdB: a stress-responsive ribonuclease-binding regulator of E. coli RNase III activity. Genes Dev 2009; 22:3497-508. [PMID: 19141481 DOI: 10.1101/gad.1729508] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The broad cellular actions of RNase III family enzymes include ribosomal RNA (rRNA) processing, mRNA decay, and the generation of noncoding microRNAs in both prokaryotes and eukaryotes. Here we report that YmdB, an evolutionarily conserved 18.8-kDa protein of Escherichia coli of previously unknown function, is a regulator of RNase III cleavages. We show that YmdB functions by interacting with a site in the RNase III catalytic region, that expression of YmdB is transcriptionally activated by both cold-shock stress and the entry of cells into stationary phase, and that this activation requires the sigma-factor-encoding gene, rpoS. We discovered that down-regulation of RNase III activity occurs during both stresses and is dependent on YmdB production during cold shock; in contrast, stationary-phase regulation was unperturbed in YmdB-null mutant bacteria, indicating the existence of additional, YmdB-independent, factors that dynamically regulate RNase III actions during normal cell growth. Our results reveal the previously unsuspected role of ribonuclease-binding proteins in the regulation of RNase III activity.
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Affiliation(s)
- Kwang-sun Kim
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
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36
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Autoregulation of AbsB (RNase III) expression in Streptomyces coelicolor by endoribonucleolytic cleavage of absB operon transcripts. J Bacteriol 2008; 190:5526-30. [PMID: 18539734 DOI: 10.1128/jb.00558-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Streptomyces coelicolor absB gene encodes an RNase III family endoribonuclease and is normally essential for antibiotic biosynthesis. Here we report that AbsB controls its own expression by sequentially and site specifically cleaving stem-loop segments of its polycistronic transcript. Our results demonstrate a ribonucleolytic regulatory role for AbsB in vivo.
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37
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Heterodimer-based analysis of subunit and domain contributions to double-stranded RNA processing by Escherichia coli RNase III in vitro. Biochem J 2008; 410:39-48. [PMID: 17953512 DOI: 10.1042/bj20071047] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Members of the RNase III family are the primary cellular agents of dsRNA (double-stranded RNA) processing. Bacterial RNases III function as homodimers and contain two dsRBDs (dsRNA-binding domains) and two catalytic sites. The potential for functional cross-talk between the catalytic sites and the requirement for both dsRBDs for processing activity are not known. It is shown that an Escherichia coli RNase III heterodimer that contains a single functional wt (wild-type) catalytic site and an inactive catalytic site (RNase III[E117A/wt]) cleaves a substrate with a single scissile bond with a k(cat) value that is one-half that of wt RNase III, but exhibits an unaltered K(m). Moreover, RNase III[E117A/wt] cleavage of a substrate containing two scissile bonds generates singly cleaved intermediates that are only slowly cleaved at the remaining phosphodiester linkage, and in a manner that is sensitive to excess unlabelled substrate. These results demonstrate the equal probability, during a single binding event, of placement of a scissile bond in a functional or nonfunctional catalytic site of the heterodimer and reveal a requirement for substrate dissociation and rebinding for cleavage of both phosphodiester linkages by the mutant heterodimer. The rate of phosphodiester hydrolysis by RNase III[E117A/wt] has the same dependence on Mg(2+) ion concentration as that of the wt enzyme, and exhibits a Hill coefficient (h) of 2.0+/-0.1, indicating that the metal ion dependence essentially reflects a single catalytic site that employs a two-Mg(2+)-ion mechanism. Whereas an E. coli RNase III mutant that lacks both dsRBDs is inactive, a heterodimer that contains a single dsRBD exhibits significant catalytic activity. These findings support a reaction pathway involving the largely independent action of the dsRBDs and the catalytic sites in substrate recognition and cleavage respectively.
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38
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Gimenez-Barcons M, Clotet B, Martinez MA. Endoribonuclease-prepared short interfering RNAs induce effective and specific inhibition of human immunodeficiency virus type 1 replication. J Virol 2007; 81:10680-6. [PMID: 17652404 PMCID: PMC2045487 DOI: 10.1128/jvi.00950-07] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Short interfering RNAs (siRNAs) targeting viral or cellular genes can efficiently inhibit human immunodeficiency virus type 1 (HIV-1) replication. Nevertheless, optimal HIV-1 gene silencing by siRNA requires precise complementarity with most of the target sequence. The emergence of mutations in the targeted gene could lead to rapid viral escape from the siRNA. In the present study, Escherichia coli endoribonuclease III (RNase III) or mammalian Dicer was used to cleave double-stranded RNA into endoribonuclease-prepared siRNA (esiRNA). esiRNAs generate a variety of siRNAs which can efficiently and specifically target multiple sites in the cognate RNA. esiRNAs targeting the region encoding the HIV-1 reverse transcriptase (RT) reduced viral replication by 90%. The inhibition was dose dependent and sequence specific because several irrelevant esiRNAs did not inhibit HIV-1 replication. Importantly, esiRNAs obtained from the prototypic RT sequence of the HXB2 strain and from highly mutated RT sequences showed similar degrees of viral inhibition, suggesting that the heterogeneous population of esiRNAs could overcome individual mismatches in the RT sequence. Finally, esiRNAs generated by Dicer cleavage were five times more potent than those generated by bacterial RNase III digestion. These results show that esiRNAs are potent HIV-1 inhibitors. Moreover, sequence targets do not need to be highly conserved to reach a high level of viral replication inhibition.
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39
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De Paula D, Bentley MVLB, Mahato RI. Hydrophobization and bioconjugation for enhanced siRNA delivery and targeting. RNA (NEW YORK, N.Y.) 2007; 13:431-56. [PMID: 17329355 PMCID: PMC1831859 DOI: 10.1261/rna.459807] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
RNA interference (RNAi) is an evolutionarily conserved process by which double-stranded small interfering RNA (siRNA) induces sequence-specific, post-transcriptional gene silencing. Unlike other mRNA targeting strategies, RNAi takes advantage of the physiological gene silencing machinery. The potential use of siRNA as therapeutic agents has attracted great attention as a novel approach for treating severe and chronic diseases. RNAi can be achieved by either delivery of chemically synthesized siRNAs or endogenous expression of small hairpin RNA, siRNA, and microRNA (miRNA). However, the relatively high dose of siRNA required for gene silencing limits its therapeutic applications. This review discusses several strategies to improve therapeutic efficacy as well as to abrogate off-target effects and immunostimulation caused by siRNAs. There is an in-depth discussion on various issues related to the (1) mechanisms of RNAi, (2) methods of siRNA production, (3) barriers to RNAi-based therapies, (4) biodistribution, (5) design of siRNA molecules, (6) chemical modification and bioconjugation, (7) complex formation with lipids and polymers, (8) encapsulation into lipid particles, and (9) target specificity for enhanced therapeutic effectiveness.
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Affiliation(s)
- Daniel De Paula
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP Brazil
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40
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Pertzev AV, Nicholson AW. Characterization of RNA sequence determinants and antideterminants of processing reactivity for a minimal substrate of Escherichia coli ribonuclease III. Nucleic Acids Res 2006; 34:3708-21. [PMID: 16896014 PMCID: PMC1540722 DOI: 10.1093/nar/gkl459] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Members of the ribonuclease III family are the primary agents of double-stranded (ds) RNA processing in prokaryotic and eukaryotic cells. Bacterial RNase III orthologs cleave their substrates in a highly site-specific manner, which is necessary for optimal RNA function or proper decay rates. The processing reactivities of Escherichia coli RNase III substrates are determined in part by the sequence content of two discrete double-helical elements, termed the distal box (db) and proximal box (pb). A minimal substrate of E.coli RNase III, μR1.1 RNA, was characterized and used to define the db and pb sequence requirements for reactivity and their involvement in cleavage site selection. The reactivities of μR1.1 RNA sequence variants were examined in assays of cleavage and binding in vitro. The ability of all examined substitutions in the db to inhibit cleavage by weakening RNase III binding indicates that the db is a positive determinant of RNase III recognition, with the canonical UA/UG sequence conferring optimal recognition. A similar analysis showed that the pb also functions as a positive recognition determinant. It also was shown that the ability of the GC or CG bp substitution at a specific position in the pb to inhibit RNase III binding is due to the purine 2-amino group, which acts as a minor groove recognition antideterminant. In contrast, a GC or CG bp at the pb position adjacent to the scissile bond can suppress cleavage without inhibiting binding, and thus act as a catalytic antideterminant. It is shown that a single pb+db ‘set’ is sufficient to specify a cleavage site, supporting the primary function of the two boxes as positive recognition determinants. The base pair sequence control of reactivity is discussed within the context of new structural information on a post-catalytic complex of a bacterial RNase III bound to the cleaved minimal substrate.
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Affiliation(s)
| | - Allen W. Nicholson
- To whom correspondence should be addressed. Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, PA 19122, USA. Tel: +1 215 204 9048; Fax: +1 215 204 1532;
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41
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Li M, Qian H, Ichim TE, Ge WW, Popov IA, Rycerz K, Neu J, White D, Zhong R, Min WP. Induction of RNA interference in dendritic cells. Immunol Res 2005; 30:215-30. [PMID: 15477662 DOI: 10.1385/ir:30:2:215] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Dendritic cells (DC) reside at the center of the immunological universe, possessing the ability both to stimulate and inhibit various types of responses. Tolerogenic/regulatory DC with therapeutic properties can be generated through various means of manipulations in vitro and in vivo. Here we describe several attractive strategies for manipulation of DC using the novel technique of RNA interference (RNAi). Additionally, we overview some of our data regarding yet undescribed characteristics of RNAi in DC such as specific transfection strategies, persistence of gene silencing, and multi-gene silencing. The advantages of using RNAi for DC genetic manipulation gives rise to the promise of generating tailor-made DC that can be used effectively to treat a variety of immunologically mediated diseases.
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Affiliation(s)
- Mu Li
- Department of Surgery, Microbiology and Immunology, The University of Western Ontario, Canada
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42
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Sun W, Pertzev A, Nicholson AW. Catalytic mechanism of Escherichia coli ribonuclease III: kinetic and inhibitor evidence for the involvement of two magnesium ions in RNA phosphodiester hydrolysis. Nucleic Acids Res 2005; 33:807-15. [PMID: 15699182 PMCID: PMC549391 DOI: 10.1093/nar/gki197] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Escherichia coli ribonuclease III (RNase III; EC 3.1.24) is a double-stranded(ds)-RNA-specific endonuclease with key roles in diverse RNA maturation and decay pathways. E.coli RNase III is a member of a structurally distinct superfamily that includes Dicer, a central enzyme in the mechanism of RNA interference. E.coli RNase III requires a divalent metal ion for activity, with Mg2+ as the preferred species. However, neither the function(s) nor the number of metal ions involved in catalysis is known. To gain information on metal ion involvement in catalysis, the rate of cleavage of the model substrate R1.1 RNA was determined as a function of Mg2+ concentration. Single-turnover conditions were applied, wherein phosphodiester cleavage was the rate-limiting event. The measured Hill coefficient (nH) is 2.0 ± 0.1, indicative of the involvement of two Mg2+ ions in phosphodiester hydrolysis. It is also shown that 2-hydroxy-4H-isoquinoline-1,3-dione—an inhibitor of ribonucleases that employ two divalent metal ions in their catalytic sites—inhibits E.coli RNase III cleavage of R1.1 RNA. The IC50 for the compound is 14 μM for the Mg2+-supported reaction, and 8 μM for the Mn2+-supported reaction. The compound exhibits noncompetitive inhibitory kinetics, indicating that it does not perturb substrate binding. Neither the O-methylated version of the compound nor the unsubstituted imide inhibit substrate cleavage, which is consistent with a specific interaction of the N-hydroxyimide with two closely positioned divalent metal ions. A preliminary model is presented for functional roles of two divalent metal ions in the RNase III catalytic mechanism.
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Affiliation(s)
- Weimei Sun
- Department of Chemistry, Temple University1901 North 13th Street, Philadelphia, PA 19122, USA
- Center for Biotechnology, Temple University1901 North 13th Street, Philadelphia, PA 19122, USA
| | - Alexandre Pertzev
- Department of Chemistry, Temple University1901 North 13th Street, Philadelphia, PA 19122, USA
| | - Allen W. Nicholson
- Department of Chemistry, Temple University1901 North 13th Street, Philadelphia, PA 19122, USA
- Center for Biotechnology, Temple University1901 North 13th Street, Philadelphia, PA 19122, USA
- To whom correspondence should be addressed. Tel: +215 204 4410; Fax: +215 204 1532;
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Chae SS, Paik JH, Furneaux H, Hla T. Requirement for sphingosine 1-phosphate receptor-1 in tumor angiogenesis demonstrated by in vivo RNA interference. J Clin Invest 2004; 114:1082-9. [PMID: 15489955 PMCID: PMC522258 DOI: 10.1172/jci22716] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Accepted: 08/17/2004] [Indexed: 01/03/2023] Open
Abstract
Angiogenesis, or new blood vessel formation, is critical for the growth and spread of tumors. Multiple phases of this process, namely, migration, proliferation, morphogenesis, and vascular stabilization, are needed for optimal tumor growth beyond a diffusion-limited size. The sphingosine 1-phosphate (S1P) receptor-1 (S1P(1)) is required for stabilization of nascent blood vessels during embryonic development. Here we show that S1P(1) expression is strongly induced in tumor vessels. We developed a multiplex RNA interference technique to downregulate S1P(1) in mice. The small interfering RNA (siRNA) for S1P(1) specifically silenced the cognate transcript in endothelial cells and inhibited endothelial cell migration in vitro and the growth of neovessels into subcutaneous implants of Matrigel in vivo. Local injection of S1P(1) siRNA, but not a negative control siRNA, into established tumors inhibited the expression of S1P(1) polypeptide on neovessels while concomitantly suppressing vascular stabilization and angiogenesis, which resulted in dramatic suppression of tumor growth in vivo. These data suggest that S1P(1) is a critical component of the tumor angiogenic response and argue for the utility of siRNA technology in antiangiogenic therapeutics.
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Affiliation(s)
- Sung-Suk Chae
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, CT 06030-3501, USA
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Ichim TE, Li M, Qian H, Popov IA, Rycerz K, Zheng X, White D, Zhong R, Min W. RNA interference: a potent tool for gene-specific therapeutics. Am J Transplant 2004; 4:1227-36. [PMID: 15268723 PMCID: PMC7175948 DOI: 10.1111/j.1600-6143.2004.00530.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
RNA interference (RNAi) is a process through which double-stranded RNA induces the activation of cellular pathways, leading to potent and selective silencing of genes with homology to the double strand. Much excitement surrounding small interfering RNA (siRNA)-mediated therapeutics arises from the fact that this approach overcomes many of the shortcomings previously experienced with approaches such as antibodies, antisense oligonucleotides and pharmacological inhibitors. Induction of RNAi through administration of siRNA has been successfully used in treatment of hepatitis, viral infections, and cancer. In this review we will present a brief history of RNAi, methods of inducing RNAi, application of RNAi in the therapeutic setting, and the possibilities of using this highly promising approach in the context of transplantation.
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Affiliation(s)
- Thomas E. Ichim
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
| | - Mu Li
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
| | - Hua Qian
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
| | - Igor A. Popov
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
| | - Katarzyna Rycerz
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
| | - Xiufen Zheng
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
| | - David White
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
- Immunology and Transplantation, Lawson Health Research Institute, and
- Robarts Research Institute, London, ON, Canada
| | - Robert Zhong
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
- Immunology and Transplantation, Lawson Health Research Institute, and
- Robarts Research Institute, London, ON, Canada
| | - Wei‐Ping Min
- Department of Surgery, Microbiology and Immunology, University of Western Ontario
- Multi‐Organ Transplant program, London Health Sciences Centre
- Immunology and Transplantation, Lawson Health Research Institute, and
- Robarts Research Institute, London, ON, Canada
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Lamontagne B, Hannoush RN, Damha MJ, Abou Elela S. Molecular requirements for duplex recognition and cleavage by eukaryotic RNase III: discovery of an RNA-dependent DNA cleavage activity of yeast Rnt1p. J Mol Biol 2004; 338:401-18. [PMID: 15066440 DOI: 10.1016/j.jmb.2004.02.059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 02/10/2004] [Accepted: 02/14/2004] [Indexed: 11/24/2022]
Abstract
Members of the double-stranded RNA (dsRNA) specific RNase III family are known to use a conserved dsRNA-binding domain (dsRBD) to distinguish RNA A-form helices from DNA B-form ones, however, the basis of this selectivity and its effect on cleavage specificity remain unknown. Here, we directly examine the molecular requirements for dsRNA recognition and cleavage by the budding yeast RNase III (Rnt1p), and compare it to both bacterial RNase III and fission yeast RNase III (Pac1). We synthesized substrates with either chemically modified nucleotides near the cleavage sites, or with different DNA/RNA combinations, and investigated their binding and cleavage by Rnt1p. Substitution for the ribonucleotide vicinal to the scissile phosphodiester linkage with 2'-deoxy-2'-fluoro-beta-d-ribose (2' F-RNA), a deoxyribonucleotide, or a 2'-O-methylribonucleotide permitted cleavage by Rnt1p, while the introduction of a 2', 5'-phosphodiester linkage permitted binding, but not cleavage. This indicates that the position of the phosphodiester link with respect to the nuclease domain, and not the 2'-OH group, is critical for cleavage by Rnt1p. Surprisingly, Rnt1p bound to a DNA helix capped with an NGNN tetraribonucleotide loop indicating that the binding of at least one member of the RNase III family is not restricted to RNA. The results also suggest that the dsRBD may accommodate B-form DNA duplexes. Interestingly, Rnt1p, but not Pac1 nor bacterial RNase III, cleaved the DNA strand of a DNA/RNA hybrid, indicating that A-form RNA helix is not essential for cleavage by Rnt1p. In contrast, RNA/DNA hybrids bound to, but were not cleaved by Rnt1p, underscoring the critical role for the nucleotide located at 3' end of the tetraloop and suggesting an asymmetrical mode of substrate recognition. In cell extracts, the native enzyme effectively cleaved the DNA/RNA hybrid, indicating much broader Rnt1p substrate specificity than previously thought. The discovery of this novel RNA-dependent deoxyribonuclease activity has potential implications in devising new antiviral strategies that target actively transcribed DNA.
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Affiliation(s)
- Bruno Lamontagne
- Groupe ARN/RNA Group, Département de microbiologie et d'infectiologie, faculté de médecine, Université de Sherbrooke, Sherbrooke, Que., Canada J1H 5N4
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Zhang Y, Calin-Jageman I, Gurnon JR, Choi TJ, Adams B, Nicholson AW, Van Etten JL. Characterization of a chlorella virus PBCV-1 encoded ribonuclease III. Virology 2004; 317:73-83. [PMID: 14675626 DOI: 10.1016/j.virol.2003.08.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Sequence analysis of the 330-kb genome of chlorella virus PBCV-1 revealed an open reading frame, A464R, which encodes a protein with 30-35% amino acid identity to ribonuclease III (RNase III) from many bacteria. The a464r gene was cloned and the protein was expressed in Escherichia coli using the chitin-binding intein system. The recombinant PBCV-1 RNase III cleaves model dsRNA substrates, in a Mg(2+)-dependent manner, into a defined set of products. The substrate cleavage specificity overlaps, but is nonidentical to that of E. coli RNase III. The a464r gene is expressed very early during PBCV-1 infection, within 5-10 min p.i. The RNase III protein appears at 15 min p.i. and disappears by 120 min p.i. The a464r gene is highly conserved among the chlorella viruses. Phylogenetic analyses indicate that the PBCV enzyme is most closely related to Mycoplasma pneumoniae RNase III.
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Affiliation(s)
- Yuanzheng Zhang
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583-0722, USA
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Calin-Jageman I, Nicholson AW. RNA structure-dependent uncoupling of substrate recognition and cleavage by Escherichia coli ribonuclease III. Nucleic Acids Res 2003; 31:2381-92. [PMID: 12711683 PMCID: PMC154215 DOI: 10.1093/nar/gkg329] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2003] [Revised: 03/06/2003] [Accepted: 03/06/2003] [Indexed: 11/14/2022] Open
Abstract
Members of the ribonuclease III superfamily of double-strand-specific endoribonucleases participate in diverse RNA maturation and decay pathways. Ribonuclease III of the gram-negative bacterium Escherichia coli processes rRNA and mRNA precursors, and its catalytic action can regulate gene expression by controlling mRNA translation and stability. It has been proposed that E.coli RNase III can function in a non-catalytic manner, by binding RNA without cleaving phosphodiesters. However, there has been no direct evidence for this mode of action. We describe here an RNA, derived from the T7 phage R1.1 RNase III substrate, that is resistant to cleavage in vitro by E.coli RNase III but retains comparable binding affinity. R1.1[CL3B] RNA is recognized by RNase III in the same manner as R1.1 RNA, as revealed by the similar inhibitory effects of a specific mutation in both substrates. Structure-probing assays and Mfold analysis indicate that R1.1[CL3B] RNA possesses a bulge- helix-bulge motif in place of the R1.1 asymmetric internal loop. The presence of both bulges is required for uncoupling. The bulge-helix-bulge motif acts as a 'catalytic' antideterminant, which is distinct from recognition antideterminants, which inhibit RNase III binding.
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Affiliation(s)
- Irina Calin-Jageman
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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Tenllado F, Martínez-García B, Vargas M, Díaz-Ruíz JR. Crude extracts of bacterially expressed dsRNA can be used to protect plants against virus infections. BMC Biotechnol 2003; 3:3. [PMID: 12659646 PMCID: PMC153545 DOI: 10.1186/1472-6750-3-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Accepted: 03/20/2003] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Double-stranded RNA (dsRNA) is a potent initiator of gene silencing in a diverse group of organisms that includes plants, Caenorhabditis elegans, Drosophila and mammals. We have previously shown and patented that mechanical inoculation of in vitro-transcribed dsRNA derived from viral sequences specifically prevents virus infection in plants. The approach required the in vitro synthesis of large amounts of RNA involving high cost and considerable labour. RESULTS We have developed an in vivo expression system to produce large amounts of virus-derived dsRNAs in bacteria, with a view to providing a practical control of virus diseases in plants. Partially purified bacterial dsRNAs promoted specific interference with the infection in plants by two viruses belonging to the tobamovirus and potyvirus groups. Furthermore, we have demonstrated that easy to obtain, crude extracts of bacterially expressed dsRNAs are equally effective protecting plants against virus infections when sprayed onto plant surfaces by a simple procedure. Virus infectivity was significantly abolished when plants were sprayed with French Press lysates several days before virus inoculation. CONCLUSION Our approach provides an alternative to genetic transformation of plant species with dsRNA-expressing constructs capable to interfere with plant viruses. The main advantage of this mode of dsRNA production is its simplicity and its extremely low cost compared with the requirements for regenerating transgenic plants. This approach provides a reliable and potential tool, not only for plant protection against virus diseases, but also for the study of gene silencing mechanisms in plant virus infections.
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Affiliation(s)
- Francisco Tenllado
- Departamento de Biología de Plantas, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, Madrid 28006, Spain
| | - Belén Martínez-García
- Departamento de Biología de Plantas, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, Madrid 28006, Spain
| | - Marisol Vargas
- Departamento de Biología de Plantas, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, Madrid 28006, Spain
| | - José Ramón Díaz-Ruíz
- Departamento de Biología de Plantas, Centro de Investigaciones Biológicas, CSIC, Velázquez 144, Madrid 28006, Spain
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Kawasaki H, Suyama E, Iyo M, Taira K. siRNAs generated by recombinant human Dicer induce specific and significant but target site-independent gene silencing in human cells. Nucleic Acids Res 2003; 31:981-7. [PMID: 12560494 PMCID: PMC149204 DOI: 10.1093/nar/gkg184] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
RNA interference has emerged as a powerful tool for the silencing of gene expression in animals and plants. It was reported recently that 21 nt synthetic small interfering RNAs (siRNAs) specifically suppressed the expression of endogenous genes in several lines of mammalian cells. However, the efficacy of siRNAs is dependent on the presence of a specific target site within the target mRNA and it remains very difficult to predict the best or most effective target site. In this study, we demonstrate that siRNAs that have been generated in vitro by recombinant human Dicer (re-hDicer) significantly suppress not only the exogenous expression of a puromycin-resistance gene but also the endogenous expression of H-ras, c-jun and c-fos. In our system, selection of a target site is not necessary in the design of siRNAs. However, it is important to avoid homologous sequences within a target mRNA in a given protein family. Our diced siRNA system should be a powerful tool for the inactivation of genes in mammalian cells.
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Affiliation(s)
- Hiroaki Kawasaki
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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50
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Yang D, Buchholz F, Huang Z, Goga A, Chen CY, Brodsky FM, Bishop JM. Short RNA duplexes produced by hydrolysis with Escherichia coli RNase III mediate effective RNA interference in mammalian cells. Proc Natl Acad Sci U S A 2002; 99:9942-7. [PMID: 12096193 PMCID: PMC126604 DOI: 10.1073/pnas.152327299] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Small interfering RNA (siRNA) has become a powerful tool for selectively silencing gene expression in cultured mammalian cells. Because different siRNAs of the same gene have variable silencing capacities, RNA interference with synthetic siRNA is inefficient and cost intensive, especially for functional genomic studies. Here we report the use of Escherichia coli RNase III to cleave double-stranded RNA (dsRNA) into endoribonuclease-prepared siRNA (esiRNA) that can target multiple sites within an mRNA. esiRNA recapitulates the potent and specific inhibition by long dsRNA in Drosophila S2 cells. In contrast to long dsRNA, esiRNA mediates effective RNA interference without apparent nonspecific effect in cultured mammalian cells. We found that sequence-specific interference by esiRNA and the nonspecific IFN response activated by long dsRNA are independent pathways in mammalian cells. esiRNA works by eliciting the destruction of its cognate mRNA. Because of its simplicity and potency, this approach is useful for analysis of mammalian gene functions.
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Affiliation(s)
- Dun Yang
- G. W. Hooper Foundation and Department of Microbiology and Immunology, University of California, San Francisco, CA 94143-0552, USA.
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