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Evans MA, Walsh K. Clonal hematopoiesis, somatic mosaicism, and age-associated disease. Physiol Rev 2023; 103:649-716. [PMID: 36049115 PMCID: PMC9639777 DOI: 10.1152/physrev.00004.2022] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 07/19/2022] [Accepted: 08/02/2022] [Indexed: 12/15/2022] Open
Abstract
Somatic mosaicism, the occurrence of multiple genetically distinct cell clones within the same tissue, is an evitable consequence of human aging. The hematopoietic system is no exception to this, where studies have revealed the presence of expanded blood cell clones carrying mutations in preleukemic driver genes and/or genetic alterations in chromosomes. This phenomenon is referred to as clonal hematopoiesis and is remarkably prevalent in elderly individuals. While clonal hematopoiesis represents an early step toward a hematological malignancy, most individuals will never develop blood cancer. Somewhat unexpectedly, epidemiological studies have found that clonal hematopoiesis is associated with an increase in the risk of all-cause mortality and age-related disease, particularly in the cardiovascular system. Studies using murine models of clonal hematopoiesis have begun to shed light on this relationship, suggesting that driver mutations in mature blood cells can causally contribute to aging and disease by augmenting inflammatory processes. Here we provide an up-to-date review of clonal hematopoiesis within the context of somatic mosaicism and aging and describe recent epidemiological studies that have reported associations with age-related disease. We will also discuss the experimental studies that have provided important mechanistic insight into how driver mutations promote age-related disease and how this knowledge could be leveraged to treat individuals with clonal hematopoiesis.
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Affiliation(s)
- Megan A Evans
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Kenneth Walsh
- Hematovascular Biology Center, Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia
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2
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Lu L, Rao D, Niu C, Cheng L, Ma D, Xi Z. Dibenzocyclooctyne-Branched Primer Assembled Gene Nanovector and Its Potential Applications in Genome Editing. Chembiochem 2022; 23:e202100544. [PMID: 35146856 DOI: 10.1002/cbic.202100544] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 02/08/2022] [Indexed: 11/10/2022]
Abstract
The CRISPR/Cas9 system has been widely used as an efficient genome editing toolkit for gene therapy. The delivery of vectors encoding the full CRISPR/Cas9 components including Cas9 gene and gRNA expression element into cells is the crucial step to effective genome editing. However, the cargo gene sequence for genome editing is usually large, which reduces the cargo encapsulation efficiency and affects the vector size. To obtain a nanovector with high cargo gene loading capacity and biocompatible size, we report the construction of a gene nanovector from branch-PCR with a dibenzocyclooctyne (DBCO)-branched primer and establish the correlation mapping between gene length and nanovector size. The results show that the size of nanovectors can be tuned according to the gene length. According to the findings, we constructed nanovectors carrying the full CRISPR/Cas9 components in 100-200 nm and validated their application in genome editing. The results show that this kind of nanovector exhibits higher serum stability than plasmids and can reach comparable genome editing efficiency with plasmids. Hence, this type of gene nanovector obtained through branch-PCR can carry large gene cargos and maintain a biocompatible nanoscale size, which we envisage will expand its medical applications in gene therapy.
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Affiliation(s)
- Liqing Lu
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
| | - Dunkang Rao
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
| | - Cuili Niu
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
| | - Longhuai Cheng
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
| | - Dejun Ma
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
| | - Zhen Xi
- Department of Chemical Biology, State Key Laboratory of Elemento-Organic Chemistry, National Engineering Research Center of Pesticide (Tianjin), Nankai University, 300071, Tianjin, China
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3
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Mycobacterium tuberculosis CRISPR/Cas system Csm1 holds clues to the evolutionary relationship between DNA polymerase and cyclase activity. Int J Biol Macromol 2020; 170:140-149. [PMID: 33352158 DOI: 10.1016/j.ijbiomac.2020.12.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/02/2020] [Accepted: 12/02/2020] [Indexed: 10/22/2022]
Abstract
Prokaryotic CRISPR/Cas systems confer immunity against invading nucleic acids through effector complexes. Csm1, the signature protein of Type III effector complexes, catalyses cyclic oligoadenylate synthesis when in the effector complex, but not when alone, activating the Csm6 nuclease and switching on the antiviral response. Here, we provide biochemical evidence that M. tuberculosis Csm1 (MtbCsm1) has ion-dependent polymerase activity when independent of the effector complex. Structural studies provide supporting evidence that the catalytic core of the MtbCsm1 palm2 domain is almost identical to that of classical DNA polymerase Pol IV, and that the palm1 and B domains function as the other structural elements required (thumb and fingers) for DNA polymerase activity. MtbCsm1 polymerase activity is relatively weak in vitro and its functional relevance in vivo is unknown. Our structural and mutagenesis data suggest that residue K692 in the palm2 domain has been significant in the evolution of Csm1 from a polymerase to a cyclase, and support the notion that the cyclase activity of Csm1 requires the presence of other elements provided by the CRISPR/Cas effector complex. This structural rationale for Csm1 polymerase (alone) and cyclase (within the effector complex) activity should benefit future functional investigations and engineering.
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Abstract
Though making up nearly half of the known CRISPR-Cas9 family of enzymes, the Type II-C CRISPR-Cas9 has been underexplored for their molecular mechanisms and potential in safe gene editing applications. In comparison with the more popular Type II-A CRISPR-Cas9, the Type II-C enzymes are generally smaller in size and utilize longer base pairing in identification of their DNA substrates. These characteristics suggest easier portability and potentially less off-targets for Type II-C in gene editing applications. We describe identification and biochemical characterization of a thermophilic Type II-C CRISPR-Cas from Acidothermus cellulolyticus (AceCas9). We describe several library-based methods that enabled us to identify the PAM sequence and elements critical to protospacer mismatch surveillance of AceCas9.
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5
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Hand TH, Das A, Roth MO, Smith CL, Jean-Baptiste UL, Li H. Phosphate Lock Residues of Acidothermus cellulolyticus Cas9 Are Critical to Its Substrate Specificity. ACS Synth Biol 2018; 7:2908-2917. [PMID: 30458109 PMCID: PMC6525624 DOI: 10.1021/acssynbio.8b00455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite being utilized widely in genome sciences, CRISPR-Cas9 remains limited in achieving high fidelity in cleaving DNA. A better understanding of the molecular basis of Cas9 holds the key to improve Cas9-based tools. We employed direct evolution and in vitro characterizations to explore structural parameters that impact the specificity of the thermophilic Cas9 from Acidothermus cellulolyticus (AceCas9). By identifying variants that are able to cleave mismatched protospacers within the seed region, we found a critical role of the phosphate lock residues in substrate specificity in a manner that depends on their sizes and charges. Removal of the negative charge from the phosphate lock residues significantly decreases sensitivity to the guide-DNA mismatches. An increase in size of the substituted residues further reduces the sensitivity to mismatches at the first position of the protospacer. Our findings identify the phosphate lock residues as an important site for tuning the specificity and catalytic efficiency of Cas9.
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Affiliation(s)
- Travis H. Hand
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Anuska Das
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Mitchell O. Roth
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Chardasia L. Smith
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Uriel L. Jean-Baptiste
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
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6
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Peters JE, Makarova KS, Shmakov S, Koonin EV. Recruitment of CRISPR-Cas systems by Tn7-like transposons. Proc Natl Acad Sci U S A 2017; 114:E7358-E7366. [PMID: 28811374 PMCID: PMC5584455 DOI: 10.1073/pnas.1709035114] [Citation(s) in RCA: 176] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A survey of bacterial and archaeal genomes shows that many Tn7-like transposons contain minimal type I-F CRISPR-Cas systems that consist of fused cas8f and cas5f, cas7f, and cas6f genes and a short CRISPR array. Several small groups of Tn7-like transposons encompass similarly truncated type I-B CRISPR-Cas. This minimal gene complement of the transposon-associated CRISPR-Cas systems implies that they are competent for pre-CRISPR RNA (precrRNA) processing yielding mature crRNAs and target binding but not target cleavage that is required for interference. Phylogenetic analysis demonstrates that evolution of the CRISPR-Cas-containing transposons included a single, ancestral capture of a type I-F locus and two independent instances of type I-B loci capture. We show that the transposon-associated CRISPR arrays contain spacers homologous to plasmid and temperate phage sequences and, in some cases, chromosomal sequences adjacent to the transposon. We hypothesize that the transposon-encoded CRISPR-Cas systems generate displacement (R-loops) in the cognate DNA sites, targeting the transposon to these sites and thus facilitating their spread via plasmids and phages. These findings suggest the existence of RNA-guided transposition and fit the guns-for-hire concept whereby mobile genetic elements capture host defense systems and repurpose them for different stages in the life cycle of the element.
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Affiliation(s)
- Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853;
| | - Kira S Makarova
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894
| | - Sergey Shmakov
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894
- Skolkovo Institute of Science and Technology, Skolkovo, 143025, Russia
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894;
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8
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Tsui TKM, Hand TH, Duboy EC, Li H. The Impact of DNA Topology and Guide Length on Target Selection by a Cytosine-Specific Cas9. ACS Synth Biol 2017; 6:1103-1113. [PMID: 28277645 PMCID: PMC5706465 DOI: 10.1021/acssynbio.7b00050] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cas9 is an RNA-guided DNA cleavage enzyme being actively developed for genome editing and gene regulation. To be cleaved by Cas9, a double stranded DNA, or the protospacer, must be complementary to the guide region, typically 20-nucleotides in length, of the Cas9-bound guide RNA, and adjacent to a short Cas9-specific element called Protospacer Adjacent Motif (PAM). Understanding the correct juxtaposition of the protospacer- and PAM-interaction with Cas9 will enable development of versatile and safe Cas9-based technology. We report identification and biochemical characterization of Cas9 from Acidothermus cellulolyticus (AceCas9). AceCas9 depends on a 5'-NNNCC-3' PAM and is more efficient in cleaving negative supercoils than relaxed DNA. Kinetic as well as in vivo activity assays reveal that AceCas9 achieves optimal activity when combined with a guide RNA containing a 24-nucleotide complementarity region. The cytosine-specific, DNA topology-sensitive, and extended guide-dependent properties of AceCas9 may be explored for specific genome editing applications.
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Affiliation(s)
- Tsz Kin Martin Tsui
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
| | - Travis H. Hand
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
| | - Emily C. Duboy
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
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9
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Krupovic M, Béguin P, Koonin EV. Casposons: mobile genetic elements that gave rise to the CRISPR-Cas adaptation machinery. Curr Opin Microbiol 2017; 38:36-43. [PMID: 28472712 DOI: 10.1016/j.mib.2017.04.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/04/2017] [Accepted: 04/12/2017] [Indexed: 01/26/2023]
Abstract
A casposon, a member of a distinct superfamily of archaeal and bacterial self-synthesizing transposons that employ a recombinase (casposase) homologous to the Cas1 endonuclease, appears to have given rise to the adaptation module of CRISPR-Cas systems as well as the CRISPR repeats themselves. Comparison of the mechanistic features of the reactions catalyzed by the casposase and the Cas1-Cas2 heterohexamer, the CRISPR integrase, reveals close similarity but also important differences that explain the requirement of Cas2 for integration of short DNA fragments, the CRISPR spacers.
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Affiliation(s)
- Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France.
| | - Pierre Béguin
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
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10
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Nishimasu H, Nureki O. Structures and mechanisms of CRISPR RNA-guided effector nucleases. Curr Opin Struct Biol 2016; 43:68-78. [PMID: 27912110 DOI: 10.1016/j.sbi.2016.11.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/08/2016] [Accepted: 11/09/2016] [Indexed: 12/15/2022]
Abstract
In the prokaryotic CRISPR-Cas adaptive immune systems, a CRISPR RNA (crRNA) assembles with multiple or single Cas proteins to form crRNA ribonucleoprotein (crRNP) effector complexes, responsible for the destruction of invading genetic elements. Although the mechanisms of target recognition and cleavage by the crRNP effectors are quite diverse among the different types of CRISPR-Cas systems, the basic action principles of these crRNA-guided effector nucleases are highly conserved. In all of the crRNP effectors, the repeat-derived invariant and spacer-derived variable segments of the crRNA are recognized by the Cas protein(s) in sequence-dependent and sequence-independent manners, respectively, with the spacer-derived guide segment available for base pairing with target nucleic acids. Over the past few years, intensive studies have provided an atomic view of the crRNA-guided target interference mechanisms in different types of CRISPR-Cas systems. Here, we review the recent progress toward structural and mechanistic understanding of the diverse crRNP effector nucleases.
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Affiliation(s)
- Hiroshi Nishimasu
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; JST, PRESTO, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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11
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Rani R, Yadav P, Barbadikar KM, Baliyan N, Malhotra EV, Singh BK, Kumar A, Singh D. CRISPR/Cas9: a promising way to exploit genetic variation in plants. Biotechnol Lett 2016; 38:1991-2006. [PMID: 27571968 DOI: 10.1007/s10529-016-2195-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 08/18/2016] [Indexed: 12/26/2022]
Abstract
Creation of variation in existing gene pool of crop plants is the foremost requirement in crop improvement programmes. Genome editing is a tool to produce knock out of target genes either by introduction of insertion or by deletion that disrupts the function of a specific gene. The CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) system is the most recent addition to the toolbox of sequence-specific nucleases that includes ZFNs and TALENs. The CRISPR/Cas9 system allows targeted cleavage of genomic DNA guided by a small noncoding RNA, resulting in gene modifications by both non-homologous end joining and homology-directed repair mechanisms. Here, we present an overview of mechanisms of CRISPR, its potential roles in creating variation in germplasm and applications of this novel interference pathway in crop improvement. The availability of the CRISPR/Cas9 system holds promise in facilitating both forward and reverse genetics and will enhance research in crops that lack genetic resources.
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Affiliation(s)
- Reema Rani
- ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur, Rajasthan, 321303, India.
| | - Prashant Yadav
- ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur, Rajasthan, 321303, India
| | | | - Nikita Baliyan
- ICAR-Indian Agricultural Research Institute, New Delhi, India
| | | | | | - Arun Kumar
- ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur, Rajasthan, 321303, India
| | - Dhiraj Singh
- ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur, Rajasthan, 321303, India
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12
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Wright AV, Nuñez JK, Doudna JA. Biology and Applications of CRISPR Systems: Harnessing Nature's Toolbox for Genome Engineering. Cell 2016; 164:29-44. [PMID: 26771484 DOI: 10.1016/j.cell.2015.12.035] [Citation(s) in RCA: 691] [Impact Index Per Article: 86.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Indexed: 12/26/2022]
Abstract
Bacteria and archaea possess a range of defense mechanisms to combat plasmids and viral infections. Unique among these are the CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR associated) systems, which provide adaptive immunity against foreign nucleic acids. CRISPR systems function by acquiring genetic records of invaders to facilitate robust interference upon reinfection. In this Review, we discuss recent advances in understanding the diverse mechanisms by which Cas proteins respond to foreign nucleic acids and how these systems have been harnessed for precision genome manipulation in a wide array of organisms.
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Affiliation(s)
- Addison V Wright
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James K Nuñez
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute HHMI, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Center for RNA Systems Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Innovative Genomics Initiative, University of California, Berkeley, Berkeley, CA 94720, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Berkeley, CA 94720, USA.
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Abstract
The CRISPR-Cas system has emerged as a fascinating and important genome editing tool. It is now widely used in biology, biotechnology, and biomedical research in both academic and industrial settings. To improve the specificity and efficiency of Cas nucleases and to extend the applications of these systems for other areas of research, an understanding of their precise working mechanisms is crucial. In this review, we summarize current studies on the molecular structures and dynamic functions of type I and type II Cas nucleases, with a focus on target DNA searching and cleavage processes as revealed by single-molecule observations. [BMB Reports 2016; 49(4): 201-207].
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Affiliation(s)
- Seung Hwan Lee
- Center for Genome Engineering, Institute for Basic Science, Seoul 08826
| | - Sangsu Bae
- Department of Chemistry
- Institute for Materials Design, Hanyang University, Seoul 04763, Korea
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14
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Unniyampurath U, Pilankatta R, Krishnan MN. RNA Interference in the Age of CRISPR: Will CRISPR Interfere with RNAi? Int J Mol Sci 2016; 17:291. [PMID: 26927085 PMCID: PMC4813155 DOI: 10.3390/ijms17030291] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/09/2016] [Accepted: 02/15/2016] [Indexed: 12/26/2022] Open
Abstract
The recent emergence of multiple technologies for modifying gene structure has revolutionized mammalian biomedical research and enhanced the promises of gene therapy. Over the past decade, RNA interference (RNAi) based technologies widely dominated various research applications involving experimental modulation of gene expression at the post-transcriptional level. Recently, a new gene editing technology, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and the CRISPR-associated protein 9 (Cas9) (CRISPR/Cas9) system, has received unprecedented acceptance in the scientific community for a variety of genetic applications. Unlike RNAi, the CRISPR/Cas9 system is bestowed with the ability to introduce heritable precision insertions and deletions in the eukaryotic genome. The combination of popularity and superior capabilities of CRISPR/Cas9 system raises the possibility that this technology may occupy the roles currently served by RNAi and may even make RNAi obsolete. We performed a comparative analysis of the technical aspects and applications of the CRISPR/Cas9 system and RNAi in mammalian systems, with the purpose of charting out a predictive picture on whether the CRISPR/Cas9 system will eclipse the existence and future of RNAi. The conclusion drawn from this analysis is that RNAi will still occupy specific domains of biomedical research and clinical applications, under the current state of development of these technologies. However, further improvements in CRISPR/Cas9 based technology may ultimately enable it to dominate RNAi in the long term.
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Affiliation(s)
- Unnikrishnan Unniyampurath
- Program on Emerging Infectious Diseases, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore.
| | - Rajendra Pilankatta
- Department of Biochemistry and Molecular Biology, School of Biological Sciences, Central University of Kerala, Nileshwar 671328, India.
| | - Manoj N Krishnan
- Program on Emerging Infectious Diseases, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore.
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15
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Ka D, Lee H, Jung YD, Kim K, Seok C, Suh N, Bae E. Crystal Structure of Streptococcus pyogenes Cas1 and Its Interaction with Csn2 in the Type II CRISPR-Cas System. Structure 2015; 24:70-79. [PMID: 26671707 DOI: 10.1016/j.str.2015.10.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/25/2015] [Accepted: 10/20/2015] [Indexed: 11/27/2022]
Abstract
CRISPRs and Cas proteins constitute an RNA-guided microbial immune system against invading nucleic acids. Cas1 is a universal Cas protein found in all three types of CRISPR-Cas systems, and its role is implicated in new spacer acquisition during CRISPR-mediated adaptive immunity. Here, we report the crystal structure of Streptococcus pyogenes Cas1 (SpCas1) in a type II CRISPR-Cas system and characterize its interaction with S. pyogenes Csn2 (SpCsn2). The SpCas1 structure reveals a unique conformational state distinct from type I Cas1 structures, resulting in a more extensive dimerization interface, a more globular overall structure, and a disruption of potential metal-binding sites for catalysis. We demonstrate that SpCas1 directly interacts with SpCsn2, and identify the binding interface and key residues for Cas complex formation. These results provide structural information for a type II Cas1 protein, and lay a foundation for studying multiprotein Cas complexes functioning in type II CRISPR-Cas systems.
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Affiliation(s)
- Donghyun Ka
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea
| | - Hasup Lee
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea
| | - Yi-Deun Jung
- Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea
| | - Kyunggon Kim
- Clinical Proteomics Core Lab, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea; Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Chaok Seok
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea
| | - Nayoung Suh
- Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea; Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 138-736, Korea
| | - Euiyoung Bae
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea; Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
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16
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Elmore J, Deighan T, Westpheling J, Terns RM, Terns MP. DNA targeting by the type I-G and type I-A CRISPR-Cas systems of Pyrococcus furiosus. Nucleic Acids Res 2015; 43:10353-63. [PMID: 26519471 PMCID: PMC4666368 DOI: 10.1093/nar/gkv1140] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/16/2015] [Indexed: 12/26/2022] Open
Abstract
CRISPR–Cas systems silence plasmids and viruses in prokaryotes. CRISPR–Cas effector complexes contain CRISPR RNAs (crRNAs) that include sequences captured from invaders and direct CRISPR-associated (Cas) proteins to destroy corresponding invader nucleic acids. Pyrococcus furiosus (Pfu) harbors three CRISPR–Cas immune systems: a Cst (Type I-G) system with an associated Cmr (Type III-B) module at one locus, and a partial Csa (Type I-A) module (lacking known invader sequence acquisition and crRNA processing genes) at another locus. The Pfu Cmr complex cleaves complementary target RNAs, and Csa systems have been shown to target DNA, while the mechanism by which Cst complexes silence invaders is unknown. In this study, we investigated the function of the Cst as well as Csa system in Pfu strains harboring a single CRISPR–Cas system. Plasmid transformation assays revealed that the Cst and Csa systems both function by DNA silencing and utilize similar flanking sequence information (PAMs) to identify invader DNA. Silencing by each system specifically requires its associated Cas3 nuclease. crRNAs from the 7 shared CRISPR loci in Pfu are processed for use by all 3 effector complexes, and Northern analysis revealed that individual effector complexes dictate the profile of mature crRNA species that is generated.
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Affiliation(s)
- Joshua Elmore
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Trace Deighan
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Jan Westpheling
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Rebecca M Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Michael P Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA Department of Genetics, University of Georgia, Athens, GA 30602, USA Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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van Erp PBG, Jackson RN, Carter J, Golden SM, Bailey S, Wiedenheft B. Mechanism of CRISPR-RNA guided recognition of DNA targets in Escherichia coli. Nucleic Acids Res 2015; 43:8381-91. [PMID: 26243775 PMCID: PMC4787809 DOI: 10.1093/nar/gkv793] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/22/2015] [Indexed: 01/09/2023] Open
Abstract
In bacteria and archaea, short fragments of foreign DNA are integrated into Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) loci, providing a molecular memory of previous encounters with foreign genetic elements. In Escherichia coli, short CRISPR-derived RNAs are incorporated into a multi-subunit surveillance complex called Cascade (CRISPR-associated complex for antiviral defense). Recent structures of Cascade capture snapshots of this seahorse-shaped RNA-guided surveillance complex before and after binding to a DNA target. Here we determine a 3.2 Å x-ray crystal structure of Cascade in a new crystal form that provides insight into the mechanism of double-stranded DNA binding. Molecular dynamic simulations performed using available structures reveal functional roles for residues in the tail, backbone and belly subunits of Cascade that are critical for binding double-stranded DNA. Structural comparisons are used to make functional predictions and these predictions are tested in vivo and in vitro. Collectively, the results in this study reveal underlying mechanisms involved in target-induced conformational changes and highlight residues important in DNA binding and protospacer adjacent motif recognition.
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Affiliation(s)
- Paul B G van Erp
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Ryan N Jackson
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Joshua Carter
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Sarah M Golden
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Scott Bailey
- Department of Biochemistry and Molecular Biology, Johns Hopkins School of Public Health, Baltimore, MD 21205, USA
| | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
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