751
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Pride DT, Sun CL, Salzman J, Rao N, Loomer P, Armitage GC, Banfield JF, Relman DA. Analysis of streptococcal CRISPRs from human saliva reveals substantial sequence diversity within and between subjects over time. Genome Res 2011; 21:126-36. [PMID: 21149389 PMCID: PMC3012920 DOI: 10.1101/gr.111732.110] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 10/28/2010] [Indexed: 01/06/2023]
Abstract
Viruses may play an important role in the evolution of human microbial communities. Clustered regularly interspaced short palindromic repeats (CRISPRs) provide bacteria and archaea with adaptive immunity to previously encountered viruses. Little is known about CRISPR composition in members of human microbial communities, the relative rate of CRISPR locus change, or how CRISPR loci differ between the microbiota of different individuals. We collected saliva from four periodontally healthy human subjects over an 11- to 17-mo time period and analyzed CRISPR sequences with corresponding streptococcal repeats in order to improve our understanding of the predominant features of oral streptococcal adaptive immune repertoires. We analyzed a total of 6859 CRISPR bearing reads and 427,917 bacterial 16S rRNA gene sequences. We found a core (ranging from 7% to 22%) of shared CRISPR spacers that remained stable over time within each subject, but nearly a third of CRISPR spacers varied between time points. We document high spacer diversity within each subject, suggesting constant addition of new CRISPR spacers. No greater than 2% of CRISPR spacers were shared between subjects, suggesting that each individual was exposed to different virus populations. We detect changes in CRISPR spacer sequence diversity over time that may be attributable to locus diversification or to changes in streptococcal population structure, yet the composition of the populations within subjects remained relatively stable. The individual-specific and traceable character of CRISPR spacer complements could potentially open the way for expansion of the domain of personalized medicine to the oral microbiome, where lineages may be tracked as a function of health and other factors.
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Affiliation(s)
- David T Pride
- Department of Pathology, University of California, San Diego, La Jolla, California 92093, USA
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752
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Collins LJ. The RNA infrastructure: an introduction to ncRNA networks. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 722:1-19. [PMID: 21915779 DOI: 10.1007/978-1-4614-0332-6_1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The RNA infrastructure connects RNA-based functions. With transcription-to-translation processing forming the core of the network, we can visualise how RNA-based regulation, cleavage and modification are the backbone of cellular function. The key to interpreting the RNA-infrastructure is in understanding how core RNAs (tRNA, mRNA and rRNA) and other ncRNAs operate in a spatial-temporal manner, moving around the nucleus, cytoplasm and organelles during processing, or in response to environmental cues. This chapter summarises the concept of the RNA-infrastructure, and highlights examples of RNA-based networking within prokaryotes and eukaryotes. It describes how transcription-to-translation processes are tightly connected, and explores some similarities and differences between prokaryotic and eukaryotic RNA networking.
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Affiliation(s)
- Lesley J Collins
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
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753
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Kataoka K, Mochizuki K. Programmed DNA elimination in Tetrahymena: a small RNA-mediated genome surveillance mechanism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 722:156-73. [PMID: 21915788 DOI: 10.1007/978-1-4614-0332-6_10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
RNA interference (RNAi) was initially discovered as a post-transcriptional gene silencing mechanism in which short RNAs are used to target complementary RNAs for degradation. During the past several years, it has been demonstrated that RNAi-related processes are also involved in transcriptional gene silencing by directing formation of heterochromatin. The dynamic DNA rearrangement during sexual reproduction of the ciliated protozoan Tetrahymena provides an extreme example of RNAi-directed heterochromatin formation. In this process, small RNAs of ∼28-29 nt, which are processed by the Dicer-like protein Dcl1p and are associated with the Argonaute family protein Twi1p, induce heterochromatin formation at complementary genomic sequences by recruiting the histone H3 lysine 9/27 methyltransferase Ezl1p and chromodomain proteins. Eventually these heterochromatinized regions are targeted for DNA elimination. In many eukaryotes, one of the major roles for RNAi-related mechanisms is silencing transposons, and DNA elimination in Tetrahymena is also believed to have evolved as a transposon defense by removing transposon-related sequences from the somatic genome. Because DNA elimination is achieved by the coordinated actions of noncoding RNA transcription, RNA processing, RNA transport, RNA-RNA and RNA-protein interactions, RNA degradation and RNA-directed chromatin modifications, DNA elimination in Tetrahymena is a useful model to study 'RNA infrastructure'.
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Affiliation(s)
- Kensuke Kataoka
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
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754
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Babu M, Beloglazova N, Flick R, Graham C, Skarina T, Nocek B, Gagarinova A, Pogoutse O, Brown G, Binkowski A, Phanse S, Joachimiak A, Koonin EV, Savchenko A, Emili A, Greenblatt J, Edwards AM, Yakunin AF. A dual function of the CRISPR-Cas system in bacterial antivirus immunity and DNA repair. Mol Microbiol 2011; 79:484-502. [PMID: 21219465 PMCID: PMC3071548 DOI: 10.1111/j.1365-2958.2010.07465.x] [Citation(s) in RCA: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) and the associated proteins (Cas) comprise a system of adaptive immunity against viruses and plasmids in prokaryotes. Cas1 is a CRISPR-associated protein that is common to all CRISPR-containing prokaryotes but its function remains obscure. Here we show that the purified Cas1 protein of Escherichia coli (YgbT) exhibits nuclease activity against single-stranded and branched DNAs including Holliday junctions, replication forks and 5'-flaps. The crystal structure of YgbT and site-directed mutagenesis have revealed the potential active site. Genome-wide screens show that YgbT physically and genetically interacts with key components of DNA repair systems, including recB, recC and ruvB. Consistent with these findings, the ygbT deletion strain showed increased sensitivity to DNA damage and impaired chromosomal segregation. Similar phenotypes were observed in strains with deletion of CRISPR clusters, suggesting that the function of YgbT in repair involves interaction with the CRISPRs. These results show that YgbT belongs to a novel, structurally distinct family of nucleases acting on branched DNAs and suggest that, in addition to antiviral immunity, at least some components of the CRISPR-Cas system have a function in DNA repair.
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Affiliation(s)
- Mohan Babu
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Natalia Beloglazova
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Robert Flick
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Chris Graham
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Tatiana Skarina
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Boguslaw Nocek
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, IL 60439
| | - Alla Gagarinova
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Oxana Pogoutse
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Greg Brown
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Andrew Binkowski
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, IL 60439
| | - Sadhna Phanse
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, IL 60439
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894
| | - Alexei Savchenko
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
| | - Andrew Emili
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Jack Greenblatt
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Aled M. Edwards
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
- Midwest Center for Structural Genomics and Structural Biology Center, Department of Biosciences, Argonne National Laboratory, Argonne, IL 60439
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | - Alexander F. Yakunin
- Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada
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755
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Deveau H, Garneau JE, Moineau S. CRISPR/Cas system and its role in phage-bacteria interactions. Annu Rev Microbiol 2010; 64:475-93. [PMID: 20528693 DOI: 10.1146/annurev.micro.112408.134123] [Citation(s) in RCA: 404] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPRs) along with Cas proteins is a widespread system across bacteria and archaea that causes interference against foreign nucleic acids. The CRISPR/Cas system acts in at least two general stages: the adaptation stage, where the cell acquires new spacer sequences derived from foreign DNA, and the interference stage, which uses the recently acquired spacers to target and cleave invasive nucleic acid. The CRISPR/Cas system participates in a constant evolutionary battle between phages and bacteria through addition or deletion of spacers in host cells and mutations or deletion in phage genomes. This review describes the recent progress made in this fast-expanding field.
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Affiliation(s)
- Hélène Deveau
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Université Laval, Quebec City, Quebec, G1V 0A6, Canada.
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756
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Mojica FJM, Díez-Villaseñor C. The on-off switch of CRISPR immunity against phages in Escherichia coli. Mol Microbiol 2010; 77:1341-5. [PMID: 20860086 DOI: 10.1111/j.1365-2958.2010.07326.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Francisco J M Mojica
- Universidad de Alicante, Division de Microbiologia, Dpto. Fisiologia, Genetica y Microbiologia, Apartado 99, Alicante 03080, Spain.
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757
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Gudbergsdottir S, Deng L, Chen Z, Jensen JVK, Jensen LR, She Q, Garrett RA. Dynamic properties of the Sulfolobus CRISPR/Cas and CRISPR/Cmr systems when challenged with vector-borne viral and plasmid genes and protospacers. Mol Microbiol 2010; 79:35-49. [PMID: 21166892 PMCID: PMC3025118 DOI: 10.1111/j.1365-2958.2010.07452.x] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The adaptive immune CRISPR/Cas and CRISPR/Cmr systems of the crenarchaeal thermoacidophile Sulfolobus were challenged by a variety of viral and plasmid genes, and protospacers preceded by different dinucleotide motifs. The genes and protospacers were constructed to carry sequences matching individual spacers of CRISPR loci, and a range of mismatches were introduced. Constructs were cloned into vectors carrying pyrE/pyrF genes and transformed into uracil auxotrophic hosts derived from Sulfolobus solfataricus P2 or Sulfolobus islandicus REY15A. Most constructs, including those carrying different protospacer mismatches, yielded few viable transformants. These were shown to carry either partial deletions of CRISPR loci, covering a broad spectrum of sizes and including the matching spacer, or deletions of whole CRISPR/Cas modules. The deletions occurred independently of whether genes or protospacers were transcribed. For family I CRISPR loci, the presence of the protospacer CC motif was shown to be important for the occurrence of deletions. The results are consistent with a low level of random dynamic recombination occurring spontaneously, either inter-genomically or intra-genomically, at the repeat regions of Sulfolobus CRISPR loci. Moreover, the relatively high incidence of single-spacer deletions observed for S. islandicus suggests that an additional more directed mechanism operates in this organism.
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Affiliation(s)
- Soley Gudbergsdottir
- Archaea Centre, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200N Copenhagen, Denmark
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758
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Samai P, Smith P, Shuman S. Structure of a CRISPR-associated protein Cas2 from Desulfovibrio vulgaris. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:1552-6. [PMID: 21139194 DOI: 10.1107/s1744309110039801] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 10/05/2010] [Indexed: 11/10/2022]
Abstract
CRISPRs (clustered regularly interspaced short palindromic repeats) provide bacteria and archaea with RNA-guided acquired immunity to invasive DNAs. CRISPR-associated (Cas) proteins carry out the immune effector functions. Cas2 is a universal component of the CRISPR system. Here, a 1.35 Å resolution crystal structure of Cas2 from the bacterium Desulfovibrio vulgaris (DvuCas2) is reported. DvuCas2 is a homodimer, with each protomer consisting of an N-terminal βαββαβ ferredoxin fold (amino acids 1-78) to which is appended a C-terminal segment (amino acids 79-102) that includes a short 3(10)-helix and a fifth β-strand. The β5 strands align with the β4 strands of the opposite protomers, resulting in two five-stranded antiparallel β-sheets that form a sandwich at the dimer interface. The DvuCas2 dimer is stabilized by a distinctive network of hydrophilic cross-protomer side-chain interactions.
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Affiliation(s)
- Poulami Samai
- Molecular Biology Program, Sloan-Kettering Institute for Cancer Research, USA
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759
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Carte J, Pfister NT, Compton MM, Terns RM, Terns MP. Binding and cleavage of CRISPR RNA by Cas6. RNA (NEW YORK, N.Y.) 2010; 16:2181-8. [PMID: 20884784 PMCID: PMC2957057 DOI: 10.1261/rna.2230110] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The CRISPR-Cas system provides many prokaryotes with acquired resistance to viruses and other mobile genetic elements. The core components of this defense system are small, host-encoded prokaryotic silencing (psi)RNAs and Cas (CRISPR-associated) proteins. Invader-derived sequences within the psiRNAs guide Cas effector proteins to recognize and silence invader nucleic acids. Critical for CRISPR-Cas defense is processing of the psiRNAs from the primary transcripts of the host CRISPR (clustered regularly interspaced short palindromic repeat) locus. Cas6, a previously identified endoribonuclease present in a wide range of prokaryotes with the CRISPR-Cas system, binds and cleaves within the repeat sequences that separate the individual invader targeting elements in the CRISPR locus transcript. In the present study, we investigated several key aspects of the mechanism of function of Cas6 in psiRNA biogenesis. RNA footprinting reveals that Pyrococcus furiosus Cas6 binds to a 7-nt (nucleotide) sequence near the 5' end of the CRISPR RNA repeat sequence, 14 nt upstream of the Cas6 cleavage site. In addition, analysis of the cleavage activity of P. furiosus Cas6 proteins with mutations at conserved residues suggests that a triad comprised of Tyr31, His46, and Lys52 plays a critical role in catalysis, consistent with a possible general acid-base RNA cleavage mechanism for Cas6. Finally, we show that P. furiosus Cas6 remains stably associated with its cleavage products, suggesting additional roles for Cas6 in psiRNA biogenesis.
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Affiliation(s)
- Jason Carte
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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760
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Xia Z, Gardner DP, Gutell RR, Ren P. Coarse-grained model for simulation of RNA three-dimensional structures. J Phys Chem B 2010; 114:13497-506. [PMID: 20883011 PMCID: PMC2989335 DOI: 10.1021/jp104926t] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The accurate prediction of an RNA's three-dimensional structure from its "primary structure" will have a tremendous influence on the experimental design and its interpretation and ultimately our understanding of the many functions of RNA. This paper presents a general coarse-grained (CG) potential for modeling RNA 3-D structures. Each nucleotide is represented by five pseudo atoms, two for the backbone (one for the phosphate and another for the sugar) and three for the base to represent base-stacking interactions. The CG potential has been parametrized from statistical analysis of 688 RNA experimental structures. Molecular dynamic simulations of 15 RNA molecules with the length of 12-27 nucleotides have been performed using the CG potential, with performance comparable to that from all-atom simulations. For ~75% of systems tested, simulated annealing led to native-like structures at least once out of multiple repeated runs. Furthermore, with weak distance restraints based on the knowledge of three to five canonical Watson-Crick pairs, all 15 RNAs tested are successfully folded to within 6.5 Å of native structures using the CG potential and simulated annealing. The results reveal that with a limited secondary structure model the current CG potential can reliably predict the 3-D structures for small RNA molecules. We also explored an all-atom force field to construct atomic structures from the CG simulations.
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Affiliation(s)
- Zhen Xia
- Department of Biomedical Engineering, The University of Texas at Austin, TX 78712
| | - David Paul Gardner
- Section of Integrative Biology and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, TX 78712
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX 78712
| | - Robin R. Gutell
- Section of Integrative Biology and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, TX 78712
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX 78712
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, TX 78712
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, TX 78712
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761
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Papenfort K, Vogel J. Regulatory RNA in bacterial pathogens. Cell Host Microbe 2010; 8:116-27. [PMID: 20638647 DOI: 10.1016/j.chom.2010.06.008] [Citation(s) in RCA: 249] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 05/18/2010] [Accepted: 06/22/2010] [Indexed: 01/26/2023]
Abstract
Bacteria constitute a large and diverse class of infectious agents, causing devastating diseases in humans, animals, and plants. Our understanding of gene expression control, which forms the basis for successful prevention and treatment strategies, has until recently neglected the many roles that regulatory RNAs might have in bacteria. In recent years, several such regulators have been found to facilitate host-microbe interactions and act as key switches between saprophytic and pathogenic lifestyles. This review covers the versatile regulatory RNA mechanisms employed by bacterial pathogens and highlights the dynamic interplay between riboregulation and virulence factor expression.
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Affiliation(s)
- Kai Papenfort
- RNA Biology Group, Max Planck Institute for Infection Biology, Charitéplatz 1, D-10117 Berlin, Germany
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762
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Lawrence PK, Kittichotirat W, McDermott JE, Bumgarner RE. A three-way comparative genomic analysis of Mannheimia haemolytica isolates. BMC Genomics 2010; 11:535. [PMID: 20920355 PMCID: PMC3091684 DOI: 10.1186/1471-2164-11-535] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Accepted: 10/04/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mannhemia haemolytica is a Gram-negative bacterium and the principal etiological agent associated with bovine respiratory disease complex. They transform from a benign commensal to a deadly pathogen, during stress such as viral infection and transportation to feedlots and cause acute pleuropneumonia commonly known as shipping fever. The U.S beef industry alone loses more than one billion dollars annually due to shipping fever. Despite its enormous economic importance there are no specific and accurate genetic markers, which will aid in understanding the pathogenesis and epidemiology of M. haemolytica at molecular level and assist in devising an effective control strategy. DESCRIPTION During our comparative genomic sequence analysis of three Mannheimia haemolytica isolates, we identified a number of genes that are unique to each strain. These genes are "high value targets" for future studies that attempt to correlate the variable gene pool with phenotype. We also identified a number of high confidence single nucleotide polymorphisms (hcSNPs) spread throughout the genome and focused on non-synonymous SNPs in known virulence genes. These SNPs will be used to design new hcSNP arrays to study variation across strains, and will potentially aid in understanding gene regulation and the mode of action of various virulence factors. CONCLUSIONS During our analysis we identified previously unknown possible type III secretion effector proteins, clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated sequences (Cas). The presence of CRISPR regions is indicative of likely co-evolution with an associated phage. If proven functional, the presence of a type III secretion system in M. haemolytica will help us re-evaluate our approach to study host-pathogen interactions. We also identified various adhesins containing immuno-dominant domains, which may interfere with host-innate immunity and which could potentially serve as effective vaccine candidates.
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Affiliation(s)
- Paulraj K Lawrence
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA
| | | | | | - Roger E Bumgarner
- Department of Microbiology, University of Washington, Seattle, WA 98195-7242, USA
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763
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The Escherichia coli CRISPR system protects from λ lysogenization, lysogens, and prophage induction. J Bacteriol 2010; 192:6291-4. [PMID: 20889749 DOI: 10.1128/jb.00644-10] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We show that phage lysogenization, lysogens, and prophage induction are all targeted by CRISPR. The results demonstrate that genomic DNA is not immune to the CRISPR system, that the CRISPR system does not require noncytoplasmic elements, and that the system protects from phages entering and exiting the lysogenic cycle.
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764
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Shah SA, Garrett RA. CRISPR/Cas and Cmr modules, mobility and evolution of adaptive immune systems. Res Microbiol 2010; 162:27-38. [PMID: 20863886 DOI: 10.1016/j.resmic.2010.09.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 07/22/2010] [Indexed: 11/16/2022]
Abstract
CRISPR/Cas and CRISPR/Cmr immune machineries of archaea and bacteria provide an adaptive and effective defence mechanism directed specifically against viruses and plasmids. Present data suggest that both CRISPR/Cas and Cmr modules can behave like integral genetic elements. They tend to be located in the more variable regions of chromosomes and are displaced by genome shuffling mechanisms including transposition. CRISPR loci may be broken up and dispersed in chromosomes by transposons with the potential for creating genetic novelty. Both CRISPR/Cas and Cmr modules appear to exchange readily between closely related organisms where they may be subjected to strong selective pressure. It is likely that this process occurs primarily via conjugative plasmids or chromosomal conjugation. It is inferred that interdomain transfer between archaea and bacteria has occurred, albeit very rarely, despite the significant barriers imposed by their differing conjugative, transcriptional and translational mechanisms. There are parallels between the CRISPR crRNAs and eukaryal siRNAs, most notably to germ cell piRNAs which are directed, with the help of effector proteins, to silence or destroy transposons. No homologous proteins are identifiable at a sequence level between eukaryal siRNA proteins and those of archaeal or bacterial CRISPR/Cas and Cmr modules.
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Affiliation(s)
- Shiraz A Shah
- Archaea Centre, Department of Biology, Copenhagen University, DK2200 Copenhagen N, Denmark
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765
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Haurwitz RE, Jinek M, Wiedenheft B, Zhou K, Doudna JA. Sequence- and structure-specific RNA processing by a CRISPR endonuclease. Science 2010; 329:1355-8. [PMID: 20829488 PMCID: PMC3133607 DOI: 10.1126/science.1192272] [Citation(s) in RCA: 507] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many bacteria and archaea contain clustered regularly interspaced short palindromic repeats (CRISPRs) that confer resistance to invasive genetic elements. Central to this immune system is the production of CRISPR-derived RNAs (crRNAs) after transcription of the CRISPR locus. Here, we identify the endoribonuclease (Csy4) responsible for CRISPR transcript (pre-crRNA) processing in Pseudomonas aeruginosa. A 1.8 angstrom crystal structure of Csy4 bound to its cognate RNA reveals that Csy4 makes sequence-specific interactions in the major groove of the crRNA repeat stem-loop. Together with electrostatic contacts to the phosphate backbone, these enable Csy4 to bind selectively and cleave pre-crRNAs using phylogenetically conserved serine and histidine residues in the active site. The RNA recognition mechanism identified here explains sequence- and structure-specific processing by a large family of CRISPR-specific endoribonucleases.
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Affiliation(s)
- Rachel E. Haurwitz
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Martin Jinek
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Blake Wiedenheft
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Kaihong Zhou
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Jennifer A. Doudna
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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766
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Pougach K, Semenova E, Bogdanova E, Datsenko KA, Djordjevic M, Wanner BL, Severinov K. Transcription, processing and function of CRISPR cassettes in Escherichia coli. Mol Microbiol 2010; 77:1367-79. [PMID: 20624226 PMCID: PMC2939963 DOI: 10.1111/j.1365-2958.2010.07265.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CRISPR/Cas, bacterial and archaeal systems of interference with foreign genetic elements such as viruses or plasmids, consist of DNA loci called CRISPR cassettes (a set of variable spacers regularly separated by palindromic repeats) and associated cas genes. When a CRISPR spacer sequence exactly matches a sequence in a viral genome, the cell can become resistant to the virus. The CRISPR/Cas systems function through small RNAs originating from longer CRISPR cassette transcripts. While laboratory strains of Escherichia coli contain a functional CRISPR/Cas system (as judged by appearance of phage resistance at conditions of artificial co-overexpression of Cas genes and a CRISPR cassette engineered to target a λ-phage), no natural phage resistance due to CRISPR system function was observed in this best-studied organism and no E. coli CRISPR spacer matches sequences of well-studied E. coli phages. To better understand the apparently 'silent'E. coli CRISPR/Cas system, we systematically characterized processed transcripts from CRISPR cassettes. Using an engineered strain with genomically located spacer matching phage λ we show that endogenous levels of CRISPR cassette and cas genes expression allow only weak protection against infection with the phage. However, derepression of the CRISPR/Cas system by disruption of the hns gene leads to high level of protection.
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Affiliation(s)
- Ksenia Pougach
- Institutes of Molecular Genetics and Gene Biology, Russian Academy of Sciences, Moscow, Russia
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767
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Chakraborty S, Snijders AP, Chakravorty R, Ahmed M, Tarek AM, Hossain MA. Comparative network clustering of direct repeats (DRs) and cas genes confirms the possibility of the horizontal transfer of CRISPR locus among bacteria. Mol Phylogenet Evol 2010; 56:878-87. [DOI: 10.1016/j.ympev.2010.05.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 05/16/2010] [Accepted: 05/19/2010] [Indexed: 11/25/2022]
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768
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Stern A, Keren L, Wurtzel O, Amitai G, Sorek R. Self-targeting by CRISPR: gene regulation or autoimmunity? Trends Genet 2010; 26:335-40. [PMID: 20598393 PMCID: PMC2910793 DOI: 10.1016/j.tig.2010.05.008] [Citation(s) in RCA: 276] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 11/26/2022]
Abstract
The recently discovered prokaryotic immune system known as CRISPR (clustered regularly interspaced short palindromic repeats) is based on small RNAs ('spacers') that restrict phage and plasmid infection. It has been hypothesized that CRISPRs can also regulate self gene expression by utilizing spacers that target self genes. By analyzing CRISPRs from 330 organisms we found that one in every 250 spacers is self-targeting, and that such self-targeting occurs in 18% of all CRISPR-bearing organisms. However, complete lack of conservation across species, combined with abundance of degraded repeats near self-targeting spacers, suggests that self-targeting is a form of autoimmunity rather than a regulatory mechanism. We propose that accidental incorporation of self nucleic acids by CRISPR can incur an autoimmune fitness cost, and this could explain the abundance of degraded CRISPR systems across prokaryotes.
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Affiliation(s)
- Adi Stern
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Leeat Keren
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
| | - Omri Wurtzel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Gil Amitai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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769
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Aklujkar M, Lovley DR. Interference with histidyl-tRNA synthetase by a CRISPR spacer sequence as a factor in the evolution of Pelobacter carbinolicus. BMC Evol Biol 2010; 10:230. [PMID: 20667132 PMCID: PMC2923632 DOI: 10.1186/1471-2148-10-230] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 07/28/2010] [Indexed: 11/21/2022] Open
Abstract
Background Pelobacter carbinolicus, a bacterium of the family Geobacteraceae, cannot reduce Fe(III) directly or produce electricity like its relatives. How P. carbinolicus evolved is an intriguing problem. The genome of P. carbinolicus contains clustered regularly interspaced short palindromic repeats (CRISPR) separated by unique spacer sequences, which recent studies have shown to produce RNA molecules that interfere with genes containing identical sequences. Results CRISPR spacer #1, which matches a sequence within hisS, the histidyl-tRNA synthetase gene of P. carbinolicus, was shown to be expressed. Phylogenetic analysis and genetics demonstrated that a gene paralogous to hisS in the genomes of Geobacteraceae is unlikely to compensate for interference with hisS. Spacer #1 inhibited growth of a transgenic strain of Geobacter sulfurreducens in which the native hisS was replaced with that of P. carbinolicus. The prediction that interference with hisS would result in an attenuated histidyl-tRNA pool insufficient for translation of proteins with multiple closely spaced histidines, predisposing them to mutation and elimination during evolution, was investigated by comparative genomics of P. carbinolicus and related species. Several ancestral genes with high histidine demand have been lost or modified in the P. carbinolicus lineage, providing an explanation for its physiological differences from other Geobacteraceae. Conclusions The disappearance of multiheme c-type cytochromes and other genes typical of a metal-respiring ancestor from the P. carbinolicus lineage may be the consequence of spacer #1 interfering with hisS, a condition that can be reproduced in a heterologous host. This is the first successful co-introduction of an active CRISPR spacer and its target in the same cell, the first application of a chimeric CRISPR construct consisting of a spacer from one species in the context of repeats of another species, and the first report of a potential impact of CRISPR on genome-scale evolution by interference with an essential gene.
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Affiliation(s)
- Muktak Aklujkar
- University of Massachusetts Amherst, Amherst, MA 01003, USA.
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770
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Belasco JG. All things must pass: contrasts and commonalities in eukaryotic and bacterial mRNA decay. Nat Rev Mol Cell Biol 2010; 11:467-78. [PMID: 20520623 PMCID: PMC3145457 DOI: 10.1038/nrm2917] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite its universal importance for controlling gene expression, mRNA degradation was initially thought to occur by disparate mechanisms in eukaryotes and bacteria. This conclusion was based on differences in the structures used by these organisms to protect mRNA termini and in the RNases and modifying enzymes originally implicated in mRNA decay. Subsequent discoveries have identified several striking parallels between the cellular factors and molecular events that govern mRNA degradation in these two kingdoms of life. Nevertheless, some key distinctions remain, the most fundamental of which may be related to the different mechanisms by which eukaryotes and bacteria control translation initiation.
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Affiliation(s)
- Joel G Belasco
- Kimmel Center for Biology and Medicine at the Skirball Institute and Department of Microbiology, New York University School of Medicine, New York, 10016, USA.
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771
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Arraiano CM, Andrade JM, Domingues S, Guinote IB, Malecki M, Matos RG, Moreira RN, Pobre V, Reis FP, Saramago M, Silva IJ, Viegas SC. The critical role of RNA processing and degradation in the control of gene expression. FEMS Microbiol Rev 2010; 34:883-923. [PMID: 20659169 DOI: 10.1111/j.1574-6976.2010.00242.x] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The continuous degradation and synthesis of prokaryotic mRNAs not only give rise to the metabolic changes that are required as cells grow and divide but also rapid adaptation to new environmental conditions. In bacteria, RNAs can be degraded by mechanisms that act independently, but in parallel, and that target different sites with different efficiencies. The accessibility of sites for degradation depends on several factors, including RNA higher-order structure, protection by translating ribosomes and polyadenylation status. Furthermore, RNA degradation mechanisms have shown to be determinant for the post-transcriptional control of gene expression. RNases mediate the processing, decay and quality control of RNA. RNases can be divided into endonucleases that cleave the RNA internally or exonucleases that cleave the RNA from one of the extremities. Just in Escherichia coli there are >20 different RNases. RNase E is a single-strand-specific endonuclease critical for mRNA decay in E. coli. The enzyme interacts with the exonuclease polynucleotide phosphorylase (PNPase), enolase and RNA helicase B (RhlB) to form the degradosome. However, in Bacillus subtilis, this enzyme is absent, but it has other main endonucleases such as RNase J1 and RNase III. RNase III cleaves double-stranded RNA and family members are involved in RNA interference in eukaryotes. RNase II family members are ubiquitous exonucleases, and in eukaryotes, they can act as the catalytic subunit of the exosome. RNases act in different pathways to execute the maturation of rRNAs and tRNAs, and intervene in the decay of many different mRNAs and small noncoding RNAs. In general, RNases act as a global regulatory network extremely important for the regulation of RNA levels.
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Affiliation(s)
- Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
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772
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Luciano A Marraffini. Impact of CRIPSR immunity on the emergence of bacterial pathogens. Future Microbiol 2010; 5:693-5. [DOI: 10.2217/fmb.10.38] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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773
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Letarov AV, Golomidova AK, Tarasyan KK. Ecological basis for rational phage therapy. Acta Naturae 2010; 2:60-72. [PMID: 22649629 PMCID: PMC3347537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Understanding the mutual interactions of bacterial and phage populations in the environment of a human or animal body is essential in any attempt to influence these complex processes, particularly for rational phage therapy. Current knowledge on the impact of naturally occurring bacteriophages on the populations of their host bacteria, and their role in the homeostasis maintenance of a macro host, is still sketchy. The existing data suggest that different mechanisms stabilize phage-bacteria coexistence in different animal species or different body sites. The defining set of parameters governing phage infection includes specific physical, chemical, and biological conditions, such as pH, nutrient densities, host prevalence, relation to mucosa and other surfaces, the presence of phage inhibiting substances, etc. Phage therapy is also an ecological process that always implies three components that form a complex pattern of interactions: populations of the pathogen, the bacteriophages used as antibacterial agents, and the macroorganism. We present a review of contemporary data on natural bacteriophages occuring in human- and animal-body associated microbial communities, and analyze ecological and physiological considerations that determine the success of phage therapy in mammals.
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Affiliation(s)
- A V Letarov
- Winogradsky Institute of Microbiology, Russian Academy of Sciences
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774
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Karginov FV, Hannon GJ. The CRISPR system: small RNA-guided defense in bacteria and archaea. Mol Cell 2010; 37:7-19. [PMID: 20129051 DOI: 10.1016/j.molcel.2009.12.033] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 12/11/2009] [Accepted: 12/23/2009] [Indexed: 01/23/2023]
Abstract
All cellular systems evolve ways to combat predators and genomic parasites. In bacteria and archaea, numerous resistance mechanisms have developed against phage. Our understanding of this defensive repertoire has recently been expanded to include the CRISPR system of clustered, regularly interspaced short palindromic repeats. In this remarkable pathway, short sequence tags from invading genetic elements are actively incorporated into the host's CRISPR locus to be transcribed and processed into a set of small RNAs that guide the destruction of foreign genetic material. Here we review the inner workings of this adaptable and heritable immune system and draw comparisons to small RNA-guided defense mechanisms in eukaryotic cells.
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Affiliation(s)
- Fedor V Karginov
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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775
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Pul Ü, Wurm R, Arslan Z, Geißen R, Hofmann N, Wagner R. Identification and characterization ofE. coliCRISPR-caspromoters and their silencing by H-NS. Mol Microbiol 2010; 75:1495-512. [DOI: 10.1111/j.1365-2958.2010.07073.x] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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776
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Molloy S. CRISPRs hit the RNA target. Nat Rev Microbiol 2010. [DOI: 10.1038/nrmicro2305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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777
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Abstract
Microbes rely on diverse defense mechanisms that allow them to withstand viral predation and exposure to invading nucleic acid. In many Bacteria and most Archaea, clustered regularly interspaced short palindromic repeats (CRISPR) form peculiar genetic loci, which provide acquired immunity against viruses and plasmids by targeting nucleic acid in a sequence-specific manner. These hypervariable loci take up genetic material from invasive elements and build up inheritable DNA-encoded immunity over time. Conversely, viruses have devised mutational escape strategies that allow them to circumvent the CRISPR/Cas system, albeit at a cost. CRISPR features may be exploited for typing purposes, epidemiological studies, host-virus ecological surveys, building specific immunity against undesirable genetic elements, and enhancing viral resistance in domesticated microbes.
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