1
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Schiopu I, Dragomir I, Asandei A. Single molecule technique unveils the role of electrostatic interactions in ssDNA-gp32 molecular complex stability. RSC Adv 2024; 14:5449-5460. [PMID: 38352678 PMCID: PMC10862658 DOI: 10.1039/d3ra07746b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 02/07/2024] [Indexed: 02/16/2024] Open
Abstract
The exploration of single-strand DNA-binding protein (SSB)-ssDNA interactions and their crucial roles in essential biological processes lagged behind other types of protein-nucleic acid interactions, such as protein-dsDNA and protein-RNA interactions. The ssDNA binding protein gene product 32 (gp32) of the T4 bacteriophage is a central integrating component of the replication complex that must continuously bind to and unbind from transiently exposed template strands during the DNA synthesis. To gain deeper insights into the electrostatic conditions influencing the stability of the ssDNA-gp32 molecular complex, like the salt concentration or some metal ions proven to specifically bind to gp32, we employed a method that performs rapid measurements of the DNA-protein stability using an α-Hemolysin (α-HL) protein nanopore. We indirectly probed the stability of a protein-nucleic acid complex by monitoring the dissociation process between the gp32 protein and the ssDNA molecular complex in single-molecular electrophysiology experiments, but also through fluorescence spectroscopy techniques. We have shown that the complex is more stable in 0.5 M KCl solution than in 2 M KCl solution and that the presence of Zn2+ ions further increases this stability for any salt used in the present study. This method can be applied to other nucleic acid-protein molecular complexes, as well as for an accurate determination of the drug-protein carrier stability.
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Affiliation(s)
- Irina Schiopu
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
| | - Isabela Dragomir
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
| | - Alina Asandei
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
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2
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Shmakov SA, Barth ZK, Makarova KS, Wolf Y, Brover V, Peters J, Koonin E. Widespread CRISPR-derived RNA regulatory elements in CRISPR-Cas systems. Nucleic Acids Res 2023; 51:8150-8168. [PMID: 37283088 PMCID: PMC10450183 DOI: 10.1093/nar/gkad495] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/15/2023] [Accepted: 05/25/2023] [Indexed: 06/08/2023] Open
Abstract
CRISPR-cas loci typically contain CRISPR arrays with unique spacers separating direct repeats. Spacers along with portions of adjacent repeats are transcribed and processed into CRISPR(cr) RNAs that target complementary sequences (protospacers) in mobile genetic elements, resulting in cleavage of the target DNA or RNA. Additional, standalone repeats in some CRISPR-cas loci produce distinct cr-like RNAs implicated in regulatory or other functions. We developed a computational pipeline to systematically predict crRNA-like elements by scanning for standalone repeat sequences that are conserved in closely related CRISPR-cas loci. Numerous crRNA-like elements were detected in diverse CRISPR-Cas systems, mostly, of type I, but also subtype V-A. Standalone repeats often form mini-arrays containing two repeat-like sequence separated by a spacer that is partially complementary to promoter regions of cas genes, in particular cas8, or cargo genes located within CRISPR-Cas loci, such as toxins-antitoxins. We show experimentally that a mini-array from a type I-F1 CRISPR-Cas system functions as a regulatory guide. We also identified mini-arrays in bacteriophages that could abrogate CRISPR immunity by inhibiting effector expression. Thus, recruitment of CRISPR effectors for regulatory functions via spacers with partial complementarity to the target is a common feature of diverse CRISPR-Cas systems.
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Affiliation(s)
- Sergey A Shmakov
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Zachary K Barth
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Vyacheslav Brover
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
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3
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Pacesa M, Loeff L, Querques I, Muckenfuss LM, Sawicka M, Jinek M. R-loop formation and conformational activation mechanisms of Cas9. Nature 2022; 609:191-196. [PMID: 36002571 PMCID: PMC9433323 DOI: 10.1038/s41586-022-05114-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 07/14/2022] [Indexed: 12/25/2022]
Abstract
Cas9 is a CRISPR-associated endonuclease capable of RNA-guided, site-specific DNA cleavage1-3. The programmable activity of Cas9 has been widely utilized for genome editing applications4-6, yet its precise mechanisms of target DNA binding and off-target discrimination remain incompletely understood. Here we report a series of cryo-electron microscopy structures of Streptococcus pyogenes Cas9 capturing the directional process of target DNA hybridization. In the early phase of R-loop formation, the Cas9 REC2 and REC3 domains form a positively charged cleft that accommodates the distal end of the target DNA duplex. Guide-target hybridization past the seed region induces rearrangements of the REC2 and REC3 domains and relocation of the HNH nuclease domain to assume a catalytically incompetent checkpoint conformation. Completion of the guide-target heteroduplex triggers conformational activation of the HNH nuclease domain, enabled by distortion of the guide-target heteroduplex, and complementary REC2 and REC3 domain rearrangements. Together, these results establish a structural framework for target DNA-dependent activation of Cas9 that sheds light on its conformational checkpoint mechanism and may facilitate the development of novel Cas9 variants and guide RNA designs with enhanced specificity and activity.
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Affiliation(s)
- Martin Pacesa
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Luuk Loeff
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Irma Querques
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Lena M Muckenfuss
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Marta Sawicka
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Martin Jinek
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
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4
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Yoshimi K, Takeshita K, Kodera N, Shibumura S, Yamauchi Y, Omatsu M, Umeda K, Kunihiro Y, Yamamoto M, Mashimo T. Dynamic mechanisms of CRISPR interference by Escherichia coli CRISPR-Cas3. Nat Commun 2022; 13:4917. [PMID: 36042215 PMCID: PMC9427990 DOI: 10.1038/s41467-022-32618-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/09/2022] [Indexed: 11/09/2022] Open
Abstract
Type I CRISPR-Cas3 uses an RNA-guided multi Cas-protein complex, Cascade, which detects and degrades foreign nucleic acids via the helicase-nuclease Cas3 protein. Despite many studies using cryoEM and smFRET, the precise mechanism of Cas3-mediated cleavage and degradation of target DNA remains elusive. Here we reconstitute the CRISPR-Cas3 system in vitro to show how the Escherichia coli Cas3 (EcoCas3) with EcoCascade exhibits collateral non-specific single-stranded DNA (ssDNA) cleavage and target specific DNA degradation. Partial binding of EcoCascade to target DNA with tolerated mismatches within the spacer sequence, but not the PAM, elicits collateral ssDNA cleavage activity of recruited EcoCas3. Conversely, stable binding with complete R-loop formation drives EcoCas3 to nick the non-target strand (NTS) in the bound DNA. Helicase-dependent unwinding then combines with trans ssDNA cleavage of the target strand and repetitive cis cleavage of the NTS to degrade the target double-stranded DNA (dsDNA) substrate. High-speed atomic force microscopy demonstrates that EcoCas3 bound to EcoCascade repeatedly reels and releases the target DNA, followed by target fragmentation. Together, these results provide a revised model for collateral ssDNA cleavage and target dsDNA degradation by CRISPR-Cas3, furthering understanding of type I CRISPR priming and interference and informing future genome editing tools.
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Affiliation(s)
- Kazuto Yoshimi
- Division of Animal Genetics, Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan.,Division of Genome Engineering, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan
| | - Kohei Takeshita
- Life Science Research Infrastructure Group, Advanced Photon Technology Division, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan
| | - Noriyuki Kodera
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | | | - Yuko Yamauchi
- Division of Animal Genetics, Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan
| | - Mine Omatsu
- Life Science Research Infrastructure Group, Advanced Photon Technology Division, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan.,Laboratory of Macromolecular Dynamics and X-ray Crystallography, Department of Life Science, University of Hyogo, Hyogo, 678-1297, Japan
| | - Kenichi Umeda
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | | | - Masaki Yamamoto
- Life Science Research Infrastructure Group, Advanced Photon Technology Division, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan.,Laboratory of Macromolecular Dynamics and X-ray Crystallography, Department of Life Science, University of Hyogo, Hyogo, 678-1297, Japan
| | - Tomoji Mashimo
- Division of Animal Genetics, Laboratory Animal Research Center, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan. .,Division of Genome Engineering, Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan.
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5
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Cofsky JC, Soczek KM, Knott GJ, Nogales E, Doudna JA. CRISPR-Cas9 bends and twists DNA to read its sequence. Nat Struct Mol Biol 2022; 29:395-402. [PMID: 35422516 PMCID: PMC9189902 DOI: 10.1038/s41594-022-00756-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/01/2022] [Indexed: 12/28/2022]
Abstract
In bacterial defense and genome editing applications, the CRISPR-associated protein Cas9 searches millions of DNA base pairs to locate a 20-nucleotide, guide RNA-complementary target sequence that abuts a protospacer-adjacent motif (PAM). Target capture requires Cas9 to unwind DNA at candidate sequences using an unknown ATP-independent mechanism. Here we show that Cas9 sharply bends and undertwists DNA on PAM binding, thereby flipping DNA nucleotides out of the duplex and toward the guide RNA for sequence interrogation. Cryogenic-electron microscopy (cryo-EM) structures of Cas9-RNA-DNA complexes trapped at different states of the interrogation pathway, together with solution conformational probing, reveal that global protein rearrangement accompanies formation of an unstacked DNA hinge. Bend-induced base flipping explains how Cas9 'reads' snippets of DNA to locate target sites within a vast excess of nontarget DNA, a process crucial to both bacterial antiviral immunity and genome editing. This mechanism establishes a physical solution to the problem of complementarity-guided DNA search and shows how interrogation speed and local DNA geometry may influence genome editing efficiency.
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Affiliation(s)
- Joshua C Cofsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Katarzyna M Soczek
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Gavin J Knott
- Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA.
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA.
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Gladstone Institutes, University of California, San Francisco, CA, USA.
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA.
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6
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Zhang Q, Chen Z, Wang F, Zhang S, Chen H, Gu X, Wen F, Jin J, Zhang X, Huang X, Shen B, Sun B. Efficient DNA interrogation of SpCas9 governed by its electrostatic interaction with DNA beyond the PAM and protospacer. Nucleic Acids Res 2021; 49:12433-12444. [PMID: 34850124 PMCID: PMC8643646 DOI: 10.1093/nar/gkab1139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 12/26/2022] Open
Abstract
Streptococcus pyogenes Cas9 (SpCas9), a programmable RNA-guided DNA endonuclease, has been widely repurposed for biological and medical applications. Critical interactions between SpCas9 and DNA confer the high specificity of the enzyme in genome engineering. Here, we unveil that an essential SpCas9–DNA interaction located beyond the protospacer adjacent motif (PAM) is realized through electrostatic forces between four positively charged lysines among SpCas9 residues 1151–1156 and the negatively charged DNA backbone. Modulating this interaction by substituting lysines with amino acids that have distinct charges revealed a strong dependence of DNA target binding and cleavage activities of SpCas9 on the charge. Moreover, the SpCas9 mutants show markedly distinguishable DNA interaction sites beyond the PAM compared with wild-type SpCas9. Functionally, this interaction governs DNA sampling and participates in protospacer DNA unwinding during DNA interrogation. Overall, a mechanistic and functional understanding of this vital interaction explains how SpCas9 carries out efficient DNA interrogation.
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Affiliation(s)
- Qian Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ziting Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Fangzhu Wang
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Siqi Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongyu Chen
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Xueying Gu
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Fengcai Wen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiachuan Jin
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xingxu Huang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Gene Editing Center, ShanghaiTech University, Shanghai 201210, China
| | - Bin Shen
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Gene Editing Center, ShanghaiTech University, Shanghai 201210, China
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7
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Loeff L, Kerssemakers JWJ, Joo C, Dekker C. AutoStepfinder: A fast and automated step detection method for single-molecule analysis. PATTERNS 2021; 2:100256. [PMID: 34036291 PMCID: PMC8134948 DOI: 10.1016/j.patter.2021.100256] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/12/2020] [Accepted: 04/08/2021] [Indexed: 01/05/2023]
Abstract
Single-molecule techniques allow the visualization of the molecular dynamics of nucleic acids and proteins with high spatiotemporal resolution. Valuable kinetic information of biomolecules can be obtained when the discrete states within single-molecule time trajectories are determined. Here, we present a fast, automated, and bias-free step detection method, AutoStepfinder, that determines steps in large datasets without requiring prior knowledge on the noise contributions and location of steps. The analysis is based on a series of partition events that minimize the difference between the data and the fit. A dual-pass strategy determines the optimal fit and allows AutoStepfinder to detect steps of a wide variety of sizes. We demonstrate step detection for a broad variety of experimental traces. The user-friendly interface and the automated detection of AutoStepfinder provides a robust analysis procedure that enables anyone without programming knowledge to generate step fits and informative plots in less than an hour. Fast, automated, and bias-free detection of steps within single-molecule trajectories Robust step detection without any prior knowledge on the data A dual-pass strategy for the detection of steps over a wide variety of scales A user-friendly interface for a simplified step fitting procedure
Single-molecule techniques have made it possible to track individual protein complexes in real time with a nanometer spatial resolution and a millisecond timescale. Accurate determination of the dynamic states within single-molecule time traces provides valuable kinetic information that underlie the function of biological macromolecules. Here, we present a new automated step detection method called AutoStepfinder, a versatile, robust, and easy-to-use algorithm that allows researchers to determine the kinetic states within single-molecule time trajectories without any bias.
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Affiliation(s)
- Luuk Loeff
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
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8
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Abstract
CRISPR-Cas systems have become ubiquitous for genome editing in eukaryotic as well as bacterial systems. Cas9 forms a complex with a guide RNA (gRNA) and searches DNA for a matching sequence (target site) next to a protospacer adjacent motif (PAM). Once found, Cas9 cuts the DNA. Cas9 is revolutionary for the ability to change the RNA sequence and target a new site easily. However, while algorithms have been developed to predict gRNA-specific Cas9 activity, a fundamental biological understanding of gRNA-specific activity is lacking. The number of PAM sites in the genome is effectively a large pool of inhibitory substrates, competing with the target site for the Cas9/gRNA complex. We demonstrate that increasing the number of non-target sites for a given gRNA reduces on-target activity in a dose-dependent manner. Furthermore, we show that the use of Cas9 mutants with increased PAM specificity toward a smaller subset of PAMs (or smaller pool of competitive substrates) improves cutting rates, while increased PAM promiscuity decreases cutting rates. Decreasing the potential search space by increasing PAM specificity provides a path toward improving on-target activity for slower high-fidelity Cas9 variants. Engineering improved PAM specificity to reduce the competitive search space offers an alternative strategy to engineer Cas9 variants with increased specificity and maintained on-target activity.
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Affiliation(s)
- Eirik A Moreb
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Mitchell Hutmacher
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Michael D Lynch
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
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9
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Abstract
Prokaryotes have developed numerous defense strategies to combat the constant threat posed by the diverse genetic parasites that endanger them. Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas loci guard their hosts with an adaptive immune system against foreign nucleic acids. Protection starts with an immunization phase, in which short pieces of the invader's genome, known as spacers, are captured and integrated into the CRISPR locus after infection. Next, during the targeting phase, spacers are transcribed into CRISPR RNAs (crRNAs) that guide CRISPR-associated (Cas) nucleases to destroy the invader's DNA or RNA. Here we describe the many different molecular mechanisms of CRISPR targeting and how they are interconnected with the immunization phase through a third phase of the CRISPR-Cas immune response: primed spacer acquisition. In this phase, Cas proteins direct the crRNA-guided acquisition of additional spacers to achieve a more rapid and robust immunization of the population.
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Affiliation(s)
- Philip M. Nussenzweig
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - Luciano A. Marraffini
- Laboratory of Bacteriology, The Rockefeller University, New York, NY 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
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10
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Vink JNA, Brouns SJJ, Hohlbein J. Extracting Transition Rates in Particle Tracking Using Analytical Diffusion Distribution Analysis. Biophys J 2020; 119:1970-1983. [PMID: 33086040 DOI: 10.1016/j.bpj.2020.09.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/29/2020] [Accepted: 09/29/2020] [Indexed: 10/23/2022] Open
Abstract
Single-particle tracking is an important technique in the life sciences to understand the kinetics of biomolecules. The analysis of apparent diffusion coefficients in vivo, for example, enables researchers to determine whether biomolecules are moving alone, as part of a larger complex, or are bound to large cellular components such as the membrane or chromosomal DNA. A remaining challenge has been to retrieve quantitative kinetic models, especially for molecules that rapidly switch between different diffusional states. Here, we present analytical diffusion distribution analysis (anaDDA), a framework that allows for extracting transition rates from distributions of apparent diffusion coefficients calculated from short trajectories that feature less than 10 localizations per track. Under the assumption that the system is Markovian and diffusion is purely Brownian, we show that theoretically predicted distributions accurately match simulated distributions and that anaDDA outperforms existing methods to retrieve kinetics, especially in the fast regime of 0.1-10 transitions per imaging frame. AnaDDA does account for the effects of confinement and tracking window boundaries. Furthermore, we added the option to perform global fitting of data acquired at different frame times to allow complex models with multiple states to be fitted confidently. Previously, we have started to develop anaDDA to investigate the target search of CRISPR-Cas complexes. In this work, we have optimized the algorithms and reanalyzed experimental data of DNA polymerase I diffusing in live Escherichia coli. We found that long-lived DNA interaction by DNA polymerase are more abundant upon DNA damage, suggesting roles in DNA repair. We further revealed and quantified fast DNA probing interactions that last shorter than 10 ms. AnaDDA pushes the boundaries of the timescale of interactions that can be probed with single-particle tracking and is a mathematically rigorous framework that can be further expanded to extract detailed information about the behavior of biomolecules in living cells.
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Affiliation(s)
- Jochem N A Vink
- Department of Bionanoscience, Delft University of Technology, HZ Delft, the Netherlands; Kavli Institute of Nanoscience, Delft, the Netherlands
| | - Stan J J Brouns
- Department of Bionanoscience, Delft University of Technology, HZ Delft, the Netherlands; Kavli Institute of Nanoscience, Delft, the Netherlands.
| | - Johannes Hohlbein
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, the Netherlands; Microspectroscopy Reasearch Facility, Wageningen University & Research, Wageningen, the Netherlands.
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11
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Lin J, Fuglsang A, Kjeldsen AL, Sun K, Bhoobalan-Chitty Y, Peng X. DNA targeting by subtype I-D CRISPR-Cas shows type I and type III features. Nucleic Acids Res 2020; 48:10470-10478. [PMID: 32960267 PMCID: PMC7544194 DOI: 10.1093/nar/gkaa749] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/21/2020] [Accepted: 08/31/2020] [Indexed: 01/01/2023] Open
Abstract
Prokaryotic CRISPR-Cas immune systems are classified into six types based on their effector complexes which cleave dsDNA specifically (types I, II and V), ssRNA exclusively (type VI) or both ssRNA via a ruler mechanism and ssDNA unspecifically (type III). To date, no specific cleavage of ssDNA target has been reported for CRISPR-Cas. Here, we demonstrate dual dsDNA and ssDNA cleavage activities of a subtype I-D system which carries a type III Cas10-like large subunit, Cas10d. In addition to a specific dsDNA cleavage activity dependent on the HD domain of Cas10d, the helicase Cas3' and a compatible protospacer adjacent motif (PAM), the subtype I-D effector complex can cleave ssDNA that is complementary in sequence to the crRNA. Significantly, the ssDNA cleavage sites occur at 6-nt intervals and the cleavage is catalysed by the backbone subunit Csc2 (Cas7), similar to the periodic cleavage of ssRNA by the backbone subunit of type III effectors. The typical type I cleavage of dsDNA combined with the exceptional 6-nt spaced cleavage of ssDNA and the presence of a type III like large subunit provide strong evidence for the subtype I-D system being an evolutionary intermediate between type I and type III CRISPR-Cas systems.
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Affiliation(s)
- Jinzhong Lin
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Anders Fuglsang
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Anders Lynge Kjeldsen
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Kaiyan Sun
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Yuvaraj Bhoobalan-Chitty
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
| | - Xu Peng
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark
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12
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Nimkar S, Anand B. Cas3/I-C mediated target DNA recognition and cleavage during CRISPR interference are independent of the composition and architecture of Cascade surveillance complex. Nucleic Acids Res 2020; 48:2486-2501. [PMID: 31980818 PMCID: PMC7049708 DOI: 10.1093/nar/gkz1218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/17/2019] [Accepted: 01/22/2020] [Indexed: 12/26/2022] Open
Abstract
In type I CRISPR-Cas system, Cas3—a nuclease cum helicase—in cooperation with Cascade surveillance complex cleaves the target DNA. Unlike the Cascade/I-E, which is composed of five subunits, the Cascade/I-C is made of only three subunits lacking the CRISPR RNA processing enzyme Cas6, whose role is assumed by Cas5. How these differences in the composition and organization of Cascade subunits in type I-C influence the Cas3/I-C binding and its target cleavage mechanism is poorly understood. Here, we show that Cas3/I-C is intrinsically a single-strand specific promiscuous nuclease. Apart from the helicase domain, a constellation of highly conserved residues—which are unique to type I-C—located in the uncharacterized C-terminal domain appears to influence the nuclease activity. Recruited by Cascade/I-C, the HD nuclease of Cas3/I-C nicks the single-stranded region of the non-target strand and positions the helicase motor. Powered by ATP, the helicase motor reels in the target DNA, until it encounters the roadblock en route, which stimulates the HD nuclease. Remarkably, we show that Cas3/I-C supplants Cas3/I-E for CRISPR interference in type I-E in vivo, suggesting that the target cleavage mechanism is evolutionarily conserved between type I-C and type I-E despite the architectural difference exhibited by Cascade/I-C and Cascade/I-E.
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Affiliation(s)
- Siddharth Nimkar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - B Anand
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
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13
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Abstract
Many bacteria and archaea have the unique ability to heritably alter their genomes by incorporating small fragments of foreign DNA, called spacers, into CRISPR loci. Once transcribed and processed into individual CRISPR RNAs, spacer sequences guide Cas effector nucleases to destroy complementary, invading nucleic acids. Collectively, these two processes are known as the CRISPR-Cas immune response. In this Progress article, we review recent studies that have advanced our understanding of the molecular mechanisms underlying spacer acquisition and that have revealed a fundamental link between the two phases of CRISPR immunity that ensures optimal immunity from newly acquired spacers. Finally, we highlight important open questions and discuss the potential basic and applied impact of spacer acquisition research.
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Affiliation(s)
- Jon McGinn
- Laboratory of Bacteriology, The Rockefeller University, New York, NY, USA
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14
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Vink JNA, Martens KJA, Vlot M, McKenzie RE, Almendros C, Estrada Bonilla B, Brocken DJW, Hohlbein J, Brouns SJJ. Direct Visualization of Native CRISPR Target Search in Live Bacteria Reveals Cascade DNA Surveillance Mechanism. Mol Cell 2020; 77:39-50.e10. [PMID: 31735642 DOI: 10.1016/j.molcel.2019.10.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 07/31/2019] [Accepted: 10/11/2019] [Indexed: 11/24/2022]
Abstract
CRISPR-Cas systems encode RNA-guided surveillance complexes to find and cleave invading DNA elements. While it is thought that invaders are neutralized minutes after cell entry, the mechanism and kinetics of target search and its impact on CRISPR protection levels have remained unknown. Here, we visualize individual Cascade complexes in a native type I CRISPR-Cas system. We uncover an exponential relation between Cascade copy number and CRISPR interference levels, pointing to a time-driven arms race between invader replication and target search, in which 20 Cascade complexes provide 50% protection. Driven by PAM-interacting subunit Cas8e, Cascade spends half its search time rapidly probing DNA (∼30 ms) in the nucleoid. We further demonstrate that target DNA transcription and CRISPR arrays affect the integrity of Cascade and affect CRISPR interference. Our work establishes the mechanism of cellular DNA surveillance by Cascade that allows the timely detection of invading DNA in a crowded, DNA-packed environment.
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Affiliation(s)
- Jochem N A Vink
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Koen J A Martens
- Laboratory of Biophysics, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, the Netherlands; Laboratory of Bionanotechnology, Wageningen University & Research, Bornse Weilanden 9, 6708 WG Wageningen, the Netherlands
| | - Marnix Vlot
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, the Netherlands
| | - Rebecca E McKenzie
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Cristóbal Almendros
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Boris Estrada Bonilla
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Daan J W Brocken
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Leiden, the Netherlands
| | - Johannes Hohlbein
- Laboratory of Biophysics, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, the Netherlands; Microspectroscopy Research Facility, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, the Netherlands.
| | - Stan J J Brouns
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands.
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15
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Nussenzweig PM, McGinn J, Marraffini LA. Cas9 Cleavage of Viral Genomes Primes the Acquisition of New Immunological Memories. Cell Host Microbe 2019; 26:515-526.e6. [PMID: 31585845 PMCID: PMC7558852 DOI: 10.1016/j.chom.2019.09.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 02/06/2023]
Abstract
Type II CRISPR-Cas systems defend prokaryotes from bacteriophage infection through the acquisition of short viral DNA sequences known as spacers, which are transcribed into short RNA guides to specify the targets of the Cas9 nuclease. To counter the potentially devastating propagation of escaper phages with mutations in the target sequences, the host population acquires many different spacers. Whether and how pre-existing spacers in type II systems affect the acquisition of new ones is unknown. Here, we demonstrate that previously acquired spacers promote additional spacer acquisition from the vicinity of the target DNA site cleaved by Cas9. Therefore, CRISPR immune cells acquire additional spacers at the same time as they destroy the infecting virus. This anticipates the rise of escapers or related viruses that could escape targeting by the first spacer acquired. Our results thus reveal Cas9's role in the generation of immunological memories.
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Affiliation(s)
- Philip M Nussenzweig
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | - Jon McGinn
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA.
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16
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Abstract
CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against invasion by bacteriophages and other mobile genetic elements. Short fragments of invader DNA are stored as immunological memories within CRISPR (clustered regularly interspaced short palindromic repeat) arrays in the host chromosome. These arrays provide a template for RNA molecules that can guide CRISPR-associated (Cas) proteins to specifically neutralize viruses upon subsequent infection. Over the past 10 years, our understanding of CRISPR-Cas systems has benefited greatly from a number of model organisms. In particular, the study of several members of the Gram-negative Enterobacteriaceae family, especially Escherichia coli and Pectobacterium atrosepticum, have provided significant insights into the mechanisms of CRISPR-Cas immunity. In this review, we provide an overview of CRISPR-Cas systems present in members of the Enterobacteriaceae. We also detail the current mechanistic understanding of the type I-E and type I-F CRISPR-Cas systems that are commonly found in enterobacteria. Finally, we discuss how phages can escape or inactivate CRISPR-Cas systems and the measures bacteria can enact to counter these types of events.
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17
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Klompe SE, Vo PLH, Halpin-Healy TS, Sternberg SH. Transposon-encoded CRISPR-Cas systems direct RNA-guided DNA integration. Nature 2019; 571:219-225. [PMID: 31189177 DOI: 10.1038/s41586-019-1323-z] [Citation(s) in RCA: 320] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/04/2019] [Indexed: 11/09/2022]
Abstract
Conventional CRISPR-Cas systems maintain genomic integrity by leveraging guide RNAs for the nuclease-dependent degradation of mobile genetic elements, including plasmids and viruses. Here we describe a notable inversion of this paradigm, in which bacterial Tn7-like transposons have co-opted nuclease-deficient CRISPR-Cas systems to catalyse RNA-guided integration of mobile genetic elements into the genome. Programmable transposition of Vibrio cholerae Tn6677 in Escherichia coli requires CRISPR- and transposon-associated molecular machineries, including a co-complex between the DNA-targeting complex Cascade and the transposition protein TniQ. Integration of donor DNA occurs in one of two possible orientations at a fixed distance downstream of target DNA sequences, and can accommodate variable length genetic payloads. Deep-sequencing experiments reveal highly specific, genome-wide DNA insertion across dozens of unique target sites. This discovery of a fully programmable, RNA-guided integrase lays the foundation for genomic manipulations that obviate the requirements for double-strand breaks and homology-directed repair.
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Affiliation(s)
- Sanne E Klompe
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Phuc L H Vo
- Department of Pharmacology, Columbia University, New York, NY, USA
| | - Tyler S Halpin-Healy
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Samuel H Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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18
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Dolan AE, Hou Z, Xiao Y, Gramelspacher MJ, Heo J, Howden SE, Freddolino PL, Ke A, Zhang Y. Introducing a Spectrum of Long-Range Genomic Deletions in Human Embryonic Stem Cells Using Type I CRISPR-Cas. Mol Cell 2019; 74:936-950.e5. [PMID: 30975459 PMCID: PMC6555677 DOI: 10.1016/j.molcel.2019.03.014] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 02/04/2019] [Accepted: 03/13/2019] [Indexed: 01/08/2023]
Abstract
CRISPR-Cas systems enable microbial adaptive immunity and provide eukaryotic genome editing tools. These tools employ a single effector enzyme of type II or V CRISPR to generate RNA-guided, precise genome breaks. Here we demonstrate the feasibility of using type I CRISPR-Cas to effectively introduce a spectrum of long-range chromosomal deletions with a single RNA guide in human embryonic stem cells and HAP1 cells. Type I CRISPR systems rely on the multi-subunit ribonucleoprotein (RNP) complex Cascade to identify DNA targets and on the helicase-nuclease enzyme Cas3 to degrade DNA processively. With RNP delivery of T. fusca Cascade and Cas3, we obtained 13%-60% editing efficiency. Long-range PCR-based and high-throughput-sequencing-based lesion analyses reveal that a variety of deletions, ranging from a few hundred base pairs to 100 kilobases, are created upstream of the target site. These results highlight the potential utility of type I CRISPR-Cas for long-range genome manipulations and deletion screens in eukaryotes.
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Affiliation(s)
- Adam E Dolan
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Zhonggang Hou
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA; State Key Laboratory of Natural Medicines, Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
| | - Max J Gramelspacher
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Jaewon Heo
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Sara E Howden
- Murdoch Children's Research Institute, Flemington Rd., Parkville, VIC 3052, Australia; Department of Paediatrics, University of Melbourne, Parkville, VIC 3052, Australia
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA; Department of Computational Medicine and Bioinformatics, University of Michigan, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
| | - Yan Zhang
- Department of Biological Chemistry, University of Michigan, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA.
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19
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Introducing a Spectrum of Long-Range Genomic Deletions in Human Embryonic Stem Cells Using Type I CRISPR-Cas. Mol Cell 2019. [PMID: 30975459 DOI: 10.1016/j.molcel.2019.03.014.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CRISPR-Cas systems enable microbial adaptive immunity and provide eukaryotic genome editing tools. These tools employ a single effector enzyme of type II or V CRISPR to generate RNA-guided, precise genome breaks. Here we demonstrate the feasibility of using type I CRISPR-Cas to effectively introduce a spectrum of long-range chromosomal deletions with a single RNA guide in human embryonic stem cells and HAP1 cells. Type I CRISPR systems rely on the multi-subunit ribonucleoprotein (RNP) complex Cascade to identify DNA targets and on the helicase-nuclease enzyme Cas3 to degrade DNA processively. With RNP delivery of T. fusca Cascade and Cas3, we obtained 13%-60% editing efficiency. Long-range PCR-based and high-throughput-sequencing-based lesion analyses reveal that a variety of deletions, ranging from a few hundred base pairs to 100 kilobases, are created upstream of the target site. These results highlight the potential utility of type I CRISPR-Cas for long-range genome manipulations and deletion screens in eukaryotes.
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20
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Pan S, Li Q, Deng L, Jiang S, Jin X, Peng N, Liang Y, She Q, Li Y. A seed motif for target RNA capture enables efficient immune defence by a type III-B CRISPR-Cas system. RNA Biol 2019; 16:1166-1178. [PMID: 31096876 DOI: 10.1080/15476286.2019.1618693] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas systems provide an adaptive defence against foreign nucleic acids guided by small RNAs (crRNAs) in archaea and bacteria. The Type III CRISPR systems are reported to carry RNase, RNA-activated DNase and cyclic oligoadenylate (cOA) synthetase activity, and are significantly different from other CRISPR systems. However, detailed features of target recognition, which are essential for enhancing target specificity remain unknown in Type III CRISPR systems. Here, we show that the Type III-B Cmr-α system in S. islandicus generates two constant lengths of crRNA independent of the length of the spacer. Either mutation at the 3'-end of crRNA or target truncation greatly influences the target capture and cleavage by the Cmr-α effector complex. Furthermore, we found that cleavage at the tag-proximal site on the target RNA by the Cmr-α RNP complex is delayed relative to the other sites, which probably provides Cas10 more time to function as a guard against invaders. Using a mutagenesis assay in vivo, we discovered that a seed motif located at the tag-distal region of the crRNA is required by Cmr1α for target RNA capture by the Cmr-α system thereby enhancing target specificity and efficiency. These findings further refine the model for immune defence of Type III-B CRISPR-Cas system, commencing on capture, cleavage and regulation.
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Affiliation(s)
- Saifu Pan
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Qi Li
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Ling Deng
- b Archaea Centre, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Suping Jiang
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Xuexia Jin
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Nan Peng
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Yunxiang Liang
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
| | - Qunxin She
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China.,b Archaea Centre, Department of Biology, University of Copenhagen , Copenhagen , Denmark
| | - Yingjun Li
- a State Key Laboratory of Agricultural Microbiology and College of Life Science and Technology, Huazhong Agricultural University , Wuhan , China
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21
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Musharova O, Sitnik V, Vlot M, Savitskaya E, Datsenko KA, Krivoy A, Fedorov I, Semenova E, Brouns SJJ, Severinov K. Systematic analysis of Type I-E Escherichia coli CRISPR-Cas PAM sequences ability to promote interference and primed adaptation. Mol Microbiol 2019; 111:1558-1570. [PMID: 30875129 PMCID: PMC6568314 DOI: 10.1111/mmi.14237] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2019] [Indexed: 01/05/2023]
Abstract
CRISPR interference occurs when a protospacer recognized by the CRISPR RNA is destroyed by Cas effectors. In Type I CRISPR‐Cas systems, protospacer recognition can lead to «primed adaptation» – acquisition of new spacers from in cis located sequences. Type I CRISPR‐Cas systems require the presence of a trinucleotide protospacer adjacent motif (PAM) for efficient interference. Here, we investigated the ability of each of 64 possible trinucleotides located at the PAM position to induce CRISPR interference and primed adaptation by the Escherichia coli Type I‐E CRISPR‐Cas system. We observed clear separation of PAM variants into three groups: those unable to cause interference, those that support rapid interference and those that lead to reduced interference that occurs over extended periods of time. PAM variants unable to support interference also did not support primed adaptation; those that supported rapid interference led to no or low levels of adaptation, while those that caused attenuated levels of interference consistently led to highest levels of adaptation. The results suggest that primed adaptation is fueled by the products of CRISPR interference. Extended over time interference with targets containing «attenuated» PAM variants provides a continuous source of new spacers leading to high overall level of spacer acquisition.
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Affiliation(s)
- Olga Musharova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia
| | - Vasily Sitnik
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
| | - Marnix Vlot
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
| | - Ekaterina Savitskaya
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia
| | - Kirill A Datsenko
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Andrey Krivoy
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
| | - Ivan Fedorov
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
| | - Ekaterina Semenova
- Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Stan J J Brouns
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - Konstantin Severinov
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia.,Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA
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22
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Rollins MF, Chowdhury S, Carter J, Golden SM, Miettinen HM, Santiago-Frangos A, Faith D, Lawrence CM, Lander GC, Wiedenheft B. Structure Reveals a Mechanism of CRISPR-RNA-Guided Nuclease Recruitment and Anti-CRISPR Viral Mimicry. Mol Cell 2019; 74:132-142.e5. [PMID: 30872121 PMCID: PMC6521718 DOI: 10.1016/j.molcel.2019.02.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/21/2018] [Accepted: 01/30/2019] [Indexed: 12/14/2022]
Abstract
Bacteria and archaea have evolved sophisticated adaptive immune systems that rely on CRISPR RNA (crRNA)-guided detection and nuclease-mediated elimination of invading nucleic acids. Here, we present the cryo-electron microscopy (cryo-EM) structure of the type I-F crRNA-guided surveillance complex (Csy complex) from Pseudomonas aeruginosa bound to a double-stranded DNA target. Comparison of this structure to previously determined structures of this complex reveals a ∼180-degree rotation of the C-terminal helical bundle on the "large" Cas8f subunit. We show that the double-stranded DNA (dsDNA)-induced conformational change in Cas8f exposes a Cas2/3 "nuclease recruitment helix" that is structurally homologous to a virally encoded anti-CRISPR protein (AcrIF3). Structural homology between Cas8f and AcrIF3 suggests that AcrIF3 is a mimic of the Cas8f nuclease recruitment helix.
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MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Bacterial Proteins/metabolism
- CRISPR-Associated Proteins/chemistry
- CRISPR-Associated Proteins/genetics
- CRISPR-Associated Proteins/immunology
- CRISPR-Associated Proteins/metabolism
- CRISPR-Cas Systems
- Clustered Regularly Interspaced Short Palindromic Repeats
- Cryoelectron Microscopy
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Models, Molecular
- Molecular Mimicry
- Nucleic Acid Conformation
- Protein Conformation
- Pseudomonas aeruginosa/enzymology
- Pseudomonas aeruginosa/genetics
- Pseudomonas aeruginosa/immunology
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/chemistry
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
- Structure-Activity Relationship
- Viral Proteins/chemistry
- Viral Proteins/genetics
- Viral Proteins/immunology
- Viral Proteins/metabolism
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Affiliation(s)
- MaryClare F Rollins
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, 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
| | - Heini M Miettinen
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | | | - Dominick Faith
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - C Martin Lawrence
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, USA.
| | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.
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23
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Xue C, Zhu Y, Zhang X, Shin YK, Sashital DG. Real-Time Observation of Target Search by the CRISPR Surveillance Complex Cascade. Cell Rep 2019; 21:3717-3727. [PMID: 29281822 DOI: 10.1016/j.celrep.2017.11.110] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 10/30/2017] [Accepted: 11/29/2017] [Indexed: 12/20/2022] Open
Abstract
CRISPR-Cas systems defend bacteria and archaea against infection by bacteriophage and other threats. The central component of these systems are surveillance complexes that use guide RNAs to bind specific regions of foreign nucleic acids, marking them for destruction. Surveillance complexes must locate targets rapidly to ensure timely immune response, but the mechanism of this search process remains unclear. Here, we used single-molecule FRET to visualize how the type I-E surveillance complex Cascade searches DNA in real time. Cascade rapidly and randomly samples DNA through nonspecific electrostatic contacts, pausing at short PAM recognition sites that may be adjacent to the target. We identify Cascade motifs that are essential for either nonspecific sampling or positioning and readout of the PAM. Our findings provide a comprehensive structural and kinetic model for the Cascade target-search mechanism, revealing how CRISPR surveillance complexes can rapidly search large amounts of genetic material en route to target recognition.
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Affiliation(s)
- Chaoyou Xue
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Yicheng Zhu
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Xiangmei Zhang
- Department of Statistics, Iowa State University, Ames, IA 50011, USA
| | - Yeon-Kyun Shin
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Dipali G Sashital
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
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24
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Turkowyd B, Müller-Esparza H, Climenti V, Steube N, Endesfelder U, Randau L. Live-cell single-particle tracking photoactivated localization microscopy of Cascade-mediated DNA surveillance. Methods Enzymol 2019; 616:133-171. [PMID: 30691641 DOI: 10.1016/bs.mie.2018.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Type I CRISPR-Cas systems utilize small CRISPR RNA (crRNA) molecules to scan DNA strands for target regions. Different crRNAs are bound by several CRISPR-associated (Cas) protein subunits that form the stable ribonucleoprotein complex Cascade. The Cascade-mediated DNA surveillance process requires a sufficient degree of base-complementarity between crRNA and target sequences and relies on the recognition of small DNA motifs, termed protospacer adjacent motifs. Recently, super-resolution microscopy and single-particle tracking methods have been developed to follow individual protein complexes in live cells. Here, we described how this technology can be adapted to visualize the DNA scanning process of Cascade assemblies in Escherichia coli cells. The activity of recombinant Type I-Fv Cascade complexes of Shewanella putrefaciens CN-32 serves as a model system that facilitates comparative studies for many of the diverse CRISPR-Cas systems.
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Affiliation(s)
- Bartosz Turkowyd
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Hanna Müller-Esparza
- Prokaryotic Small RNA Biology Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Vanessa Climenti
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Niklas Steube
- Prokaryotic Small RNA Biology Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany.
| | - Lennart Randau
- LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany; Prokaryotic Small RNA Biology Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
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25
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Wang L, Mo CY, Wasserman MR, Rostøl JT, Marraffini LA, Liu S. Dynamics of Cas10 Govern Discrimination between Self and Non-self in Type III CRISPR-Cas Immunity. Mol Cell 2018; 73:278-290.e4. [PMID: 30503774 DOI: 10.1016/j.molcel.2018.11.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/11/2018] [Accepted: 11/05/2018] [Indexed: 12/26/2022]
Abstract
Adaptive immune systems must accurately distinguish between self and non-self in order to defend against invading pathogens while avoiding autoimmunity. Type III CRISPR-Cas systems employ guide RNA to recognize complementary RNA targets, which triggers the degradation of both the invader's transcripts and their template DNA. These systems can broadly eliminate foreign targets with multiple mutations but circumvent damage to the host genome. To explore the molecular basis for these features, we use single-molecule fluorescence microscopy to study the interaction between a type III-A ribonucleoprotein complex and various RNA substrates. We find that Cas10-the DNase effector of the complex-displays rapid conformational fluctuations on foreign RNA targets, but is locked in a static configuration on self RNA. Target mutations differentially modulate Cas10 dynamics and tune the CRISPR interference activity in vivo. These findings highlight the central role of the internal dynamics of CRISPR-Cas complexes in self versus non-self discrimination and target specificity.
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Affiliation(s)
- Ling Wang
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Charlie Y Mo
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Michael R Wasserman
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Jakob T Rostøl
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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26
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Künne T, Zhu Y, da Silva F, Konstantinides N, McKenzie RE, Jackson RN, Brouns S. Role of nucleotide identity in effective CRISPR target escape mutations. Nucleic Acids Res 2018; 46:10395-10404. [PMID: 30107450 PMCID: PMC6212716 DOI: 10.1093/nar/gky687] [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: 05/18/2018] [Revised: 07/16/2018] [Accepted: 08/10/2018] [Indexed: 12/26/2022] Open
Abstract
Prokaryotes use primed CRISPR adaptation to update their memory bank of spacers against invading genetic elements that have escaped CRISPR interference through mutations in their protospacer target site. We previously observed a trend that nucleotide-dependent mismatches between crRNA and the protospacer strongly influence the efficiency of primed CRISPR adaptation. Here we show that guanine-substitutions in the target strand of the protospacer are highly detrimental to CRISPR interference and interference-dependent priming, while cytosine-substitutions are more readily tolerated. Furthermore, we show that this effect is based on strongly decreased binding affinity of the effector complex Cascade for guanine-mismatched targets, while cytosine-mismatched targets only minimally affect target DNA binding. Structural modeling of Cascade-bound targets with mismatches shows that steric clashes of mismatched guanines lead to unfavorable conformations of the RNA-DNA duplex. This effect has strong implications for the natural selection of target site mutations that lead to effective escape from type I CRISPR-Cas systems.
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MESH Headings
- Base Pairing
- Base Sequence
- CRISPR-Associated Proteins/genetics
- CRISPR-Associated Proteins/metabolism
- CRISPR-Cas Systems
- Clustered Regularly Interspaced Short Palindromic Repeats
- Cytosine/chemistry
- Cytosine/metabolism
- DNA Helicases/genetics
- DNA Helicases/metabolism
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Guanine/chemistry
- Guanine/metabolism
- Mutation
- Plasmids/chemistry
- Plasmids/metabolism
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/chemistry
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
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Affiliation(s)
- Tim Künne
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Laboratory of Food Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Yifan Zhu
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Fausia da Silva
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Nico Konstantinides
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Rebecca E McKenzie
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Ryan N Jackson
- Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT, USA
| | - Stan JJ Brouns
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- Kavli Institute of Nanoscience, Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
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27
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Dillard KE, Brown MW, Johnson NV, Xiao Y, Dolan A, Hernandez E, Dahlhauser SD, Kim Y, Myler LR, Anslyn EV, Ke A, Finkelstein IJ. Assembly and Translocation of a CRISPR-Cas Primed Acquisition Complex. Cell 2018; 175:934-946.e15. [PMID: 30343903 DOI: 10.1016/j.cell.2018.09.039] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 07/20/2018] [Accepted: 09/18/2018] [Indexed: 12/18/2022]
Abstract
CRISPR-Cas systems confer an adaptive immunity against viruses. Following viral injection, Cas1-Cas2 integrates segments of the viral genome (spacers) into the CRISPR locus. In type I CRISPR-Cas systems, efficient "primed" spacer acquisition and viral degradation (interference) require both the Cascade complex and the Cas3 helicase/nuclease. Here, we present single-molecule characterization of the Thermobifida fusca (Tfu) primed acquisition complex (PAC). We show that TfuCascade rapidly samples non-specific DNA via facilitated one-dimensional diffusion. Cas3 loads at target-bound Cascade and the Cascade/Cas3 complex translocates via a looped DNA intermediate. Cascade/Cas3 complexes stall at diverse protein roadblocks, resulting in a double strand break at the stall site. In contrast, Cas1-Cas2 samples DNA transiently via 3D collisions. Moreover, Cas1-Cas2 associates with Cascade and translocates with Cascade/Cas3, forming the PAC. PACs can displace different protein roadblocks, suggesting a mechanism for long-range spacer acquisition. This work provides a molecular basis for the coordinated steps in CRISPR-based adaptive immunity.
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Affiliation(s)
- Kaylee E Dillard
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Maxwell W Brown
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Nicole V Johnson
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Adam Dolan
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Erik Hernandez
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Samuel D Dahlhauser
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Yoori Kim
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Logan R Myler
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Eric V Anslyn
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA.
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28
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Xiao Y, Luo M, Dolan AE, Liao M, Ke A. Structure basis for RNA-guided DNA degradation by Cascade and Cas3. Science 2018; 361:eaat0839. [PMID: 29880725 PMCID: PMC6537108 DOI: 10.1126/science.aat0839] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/22/2018] [Indexed: 12/27/2022]
Abstract
Type I CRISPR-Cas system features a sequential target-searching and degradation process on double-stranded DNA by the RNA-guided Cascade (CRISPR associated complex for antiviral defense) complex and the nuclease-helicase fusion enzyme Cas3, respectively. Here, we present a 3.7-angstrom-resolution cryo-electron microscopy (cryo-EM) structure of the Type I-E Cascade/R-loop/Cas3 complex, poised to initiate DNA degradation. Cas3 distinguishes Cascade conformations and only captures the R-loop-forming Cascade, to avoid cleaving partially complementary targets. Its nuclease domain recruits the nontarget strand (NTS) DNA at a bulged region for the nicking of single-stranded DNA. An additional 4.7-angstrom-resolution cryo-EM structure captures the postnicking state, in which the severed NTS retracts to the helicase entrance, to be threaded for adenosine 5'-triphosphate-dependent processive degradation. These snapshots form the basis for understanding RNA-guided DNA degradation in Type I-E CRISPR-Cas systems.
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Affiliation(s)
- Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Min Luo
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA
| | - Adam E Dolan
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA.
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
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29
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Singh D, Mallon J, Poddar A, Wang Y, Tippana R, Yang O, Bailey S, Ha T. Real-time observation of DNA target interrogation and product release by the RNA-guided endonuclease CRISPR Cpf1 (Cas12a). Proc Natl Acad Sci U S A 2018; 115:5444-5449. [PMID: 29735714 PMCID: PMC6003496 DOI: 10.1073/pnas.1718686115] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
CRISPR-Cas9, which imparts adaptive immunity against foreign genomic invaders in certain prokaryotes, has been repurposed for genome-engineering applications. More recently, another RNA-guided CRISPR endonuclease called Cpf1 (also known as Cas12a) was identified and is also being repurposed. Little is known about the kinetics and mechanism of Cpf1 DNA interaction and how sequence mismatches between the DNA target and guide-RNA influence this interaction. We used single-molecule fluorescence analysis and biochemical assays to characterize DNA interrogation, cleavage, and product release by three Cpf1 orthologs. Our Cpf1 data are consistent with the DNA interrogation mechanism proposed for Cas9. They both bind any DNA in search of protospacer-adjacent motif (PAM) sequences, verify the target sequence directionally from the PAM-proximal end, and rapidly reject any targets that lack a PAM or that are poorly matched with the guide-RNA. Unlike Cas9, which requires 9 bp for stable binding and ∼16 bp for cleavage, Cpf1 requires an ∼17-bp sequence match for both stable binding and cleavage. Unlike Cas9, which does not release the DNA cleavage products, Cpf1 rapidly releases the PAM-distal cleavage product, but not the PAM-proximal product. Solution pH, reducing conditions, and 5' guanine in guide-RNA differentially affected different Cpf1 orthologs. Our findings have important implications on Cpf1-based genome engineering and manipulation applications.
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MESH Headings
- Acidaminococcus/enzymology
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Clustered Regularly Interspaced Short Palindromic Repeats/genetics
- DNA Cleavage
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Single-Stranded/chemistry
- DNA, Single-Stranded/genetics
- DNA, Single-Stranded/metabolism
- Endonucleases/chemistry
- Endonucleases/genetics
- Endonucleases/metabolism
- Genome, Bacterial
- Models, Molecular
- Nucleic Acid Conformation
- Protein Binding
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/chemistry
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
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Affiliation(s)
- Digvijay Singh
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - John Mallon
- Bloomberg School of Public Health, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Anustup Poddar
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Yanbo Wang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ramreddy Tippana
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Olivia Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Scott Bailey
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Bloomberg School of Public Health, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205;
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205
- Howard Hughes Medical Institute, Baltimore, MD 21205
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30
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Abstract
Most everyday processes in life involve a necessity for an entity to locate its target. On a cellular level, many proteins have to find their target to perform their function. From gene-expression regulation to DNA repair to host defense, numerous nucleic acid-interacting proteins use distinct target search mechanisms. Several proteins achieve that with the help of short RNA strands known as guides. This review focuses on single-molecule advances studying the target search and recognition mechanism of Argonaute and CRISPR (clustered regularly interspaced short palindromic repeats) systems. We discuss different steps involved in search and recognition, from the initial complex prearrangement into the target-search competent state to the final proofreading steps. We focus on target search mechanisms that range from weak interactions, to one- and three-dimensional diffusion, to conformational proofreading. We compare the mechanisms of Argonaute and CRISPR with a well-studied target search system, RecA.
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Affiliation(s)
- Viktorija Globyte
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands; , ,
| | - Sung Hyun Kim
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands; , ,
- School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Chirlmin Joo
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands; , ,
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31
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Loeff L, Brouns SJJ, Joo C. Repetitive DNA Reeling by the Cascade-Cas3 Complex in Nucleotide Unwinding Steps. Mol Cell 2018; 70:385-394.e3. [PMID: 29706536 DOI: 10.1016/j.molcel.2018.03.031] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/23/2018] [Accepted: 03/24/2018] [Indexed: 01/12/2023]
Abstract
CRISPR-Cas provides RNA-guided adaptive immunity against invading genetic elements. Interference in type I systems relies on the RNA-guided Cascade complex for target DNA recognition and the Cas3 helicase/nuclease protein for target degradation. Even though the biochemistry of CRISPR interference has been largely covered, the biophysics of DNA unwinding and coupling of the helicase and nuclease domains of Cas3 remains elusive. Here, we employed single-molecule Förster resonance energy transfer (FRET) to probe the helicase activity with high spatiotemporal resolution. We show that Cas3 remains tightly associated with the target-bound Cascade complex while reeling the DNA using a spring-loaded mechanism. This spring-loaded reeling occurs in distinct bursts of 3 bp, which underlie three successive 1-nt unwinding events. Reeling is highly repetitive, allowing Cas3 to repeatedly present its inefficient nuclease domain with single-strand DNA (ssDNA) substrate. Our study reveals that the discontinuous helicase properties of Cas3 and its tight interaction with Cascade ensure controlled degradation of target DNA only.
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Affiliation(s)
- Luuk Loeff
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, Delft 2629HZ, the Netherlands
| | - Stan J J Brouns
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, Delft 2629HZ, the Netherlands; Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen 6708WE, the Netherlands.
| | - Chirlmin Joo
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, Delft 2629HZ, the Netherlands.
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32
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Ray S, Widom JR, Walter NG. Life under the Microscope: Single-Molecule Fluorescence Highlights the RNA World. Chem Rev 2018; 118:4120-4155. [PMID: 29363314 PMCID: PMC5918467 DOI: 10.1021/acs.chemrev.7b00519] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The emergence of single-molecule (SM) fluorescence techniques has opened up a vast new toolbox for exploring the molecular basis of life. The ability to monitor individual biomolecules in real time enables complex, dynamic folding pathways to be interrogated without the averaging effect of ensemble measurements. In parallel, modern biology has been revolutionized by our emerging understanding of the many functions of RNA. In this comprehensive review, we survey SM fluorescence approaches and discuss how the application of these tools to RNA and RNA-containing macromolecular complexes in vitro has yielded significant insights into the underlying biology. Topics covered include the three-dimensional folding landscapes of a plethora of isolated RNA molecules, their assembly and interactions in RNA-protein complexes, and the relation of these properties to their biological functions. In all of these examples, the use of SM fluorescence methods has revealed critical information beyond the reach of ensemble averages.
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Affiliation(s)
| | | | - Nils G. Walter
- Department of Chemistry, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA
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33
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Determining the Specificity of Cascade Binding, Interference, and Primed Adaptation In Vivo in the Escherichia coli Type I-E CRISPR-Cas System. mBio 2018; 9:mBio.02100-17. [PMID: 29666291 PMCID: PMC5904413 DOI: 10.1128/mbio.02100-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In clustered regularly interspaced short palindromic repeat (CRISPR)-Cas (CRISPR-associated) immunity systems, short CRISPR RNAs (crRNAs) are bound by Cas proteins, and these complexes target invading nucleic acid molecules for degradation in a process known as interference. In type I CRISPR-Cas systems, the Cas protein complex that binds DNA is known as Cascade. Association of Cascade with target DNA can also lead to acquisition of new immunity elements in a process known as primed adaptation. Here, we assess the specificity determinants for Cascade-DNA interaction, interference, and primed adaptation in vivo, for the type I-E system of Escherichia coli Remarkably, as few as 5 bp of crRNA-DNA are sufficient for association of Cascade with a DNA target. Consequently, a single crRNA promotes Cascade association with numerous off-target sites, and the endogenous E. coli crRNAs direct Cascade binding to >100 chromosomal sites. In contrast to the low specificity of Cascade-DNA interactions, >18 bp are required for both interference and primed adaptation. Hence, Cascade binding to suboptimal, off-target sites is inert. Our data support a model in which the initial Cascade association with DNA targets requires only limited sequence complementarity at the crRNA 5' end whereas recruitment and/or activation of the Cas3 nuclease, a prerequisite for interference and primed adaptation, requires extensive base pairing.IMPORTANCE Many bacterial and archaeal species encode CRISPR-Cas immunity systems that protect against invasion by foreign DNA. In the Escherichia coli CRISPR-Cas system, a protein complex, Cascade, binds 61-nucleotide (nt) CRISPR RNAs (crRNAs). The Cascade complex is directed to invading DNA molecules through base pairing between the crRNA and target DNA. This leads to recruitment of the Cas3 nuclease, which destroys the invading DNA molecule and promotes acquisition of new immunity elements. We made the first in vivo measurements of Cascade binding to DNA targets. Thus, we show that Cascade binding to DNA is highly promiscuous; endogenous E. coli crRNAs can direct Cascade binding to >100 chromosomal locations. In contrast, we show that targeted degradation and acquisition of new immunity elements require highly specific association of Cascade with DNA, limiting CRISPR-Cas function to the appropriate targets.
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34
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Singh D, Wang Y, Mallon J, Yang O, Fei J, Poddar A, Ceylan D, Bailey S, Ha T. Mechanisms of improved specificity of engineered Cas9s revealed by single-molecule FRET analysis. Nat Struct Mol Biol 2018; 25:347-354. [PMID: 29622787 PMCID: PMC6195204 DOI: 10.1038/s41594-018-0051-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 02/27/2018] [Indexed: 12/27/2022]
Abstract
Cas9 (from Streptococcus pyogenes) in complex with a guide RNA targets complementary DNA for cleavage. Here, we developed a single-molecule FRET analysis to study the mechanisms of specificity enhancement of two engineered Cas9s (eCas9 and Cas9-HF1). A DNA-unwinding assay showed that mismatches affect cleavage reactions through rebalancing the unwinding-rewinding equilibrium. Increasing PAM-distal mismatches facilitates rewinding, and the associated cleavage impairment shows that cleavage proceeds from the unwound state. Engineered Cas9s depopulate the unwound state more readily with mismatches. The intrinsic cleavage rate is much lower for engineered Cas9s, preventing cleavage from transiently unwound off-targets. Engineered Cas9s require approximately one additional base pair match for stable binding, freeing them from sites that would otherwise sequester them. Therefore, engineered Cas9s achieve their improved specificity by inhibiting stable DNA binding to partially matching sequences, making DNA unwinding more sensitive to mismatches and slowing down the intrinsic cleavage reaction.
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Affiliation(s)
- Digvijay Singh
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yanbo Wang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - John Mallon
- Bloomberg School of Public Health, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Olivia Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jingyi Fei
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Anustup Poddar
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Damon Ceylan
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Scott Bailey
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Bloomberg School of Public Health, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Howard Hughes Medical Institute, Baltimore, MD, USA.
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35
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Singh D, Ha T. Understanding the Molecular Mechanisms of the CRISPR Toolbox Using Single Molecule Approaches. ACS Chem Biol 2018; 13:516-526. [PMID: 29394047 DOI: 10.1021/acschembio.7b00905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adaptive immunity against foreign genetic elements conferred by the CRISPR systems in microbial species has been repurposed as a revolutionary technology for wide-ranging biological applications-chiefly genome engineering. Biochemical, structural, genetic, and genomics studies have revealed important insights into their function and mechanisms, but most ensemble studies cannot observe structural changes of these molecules during their function and are often blind to key reaction intermediates. Here, we review the use of single molecule approaches such as fluorescent particle tracking, FRET, magnetic tweezers, and atomic force microscopy imaging in improving our understanding of the CRISPR toolbox.
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Affiliation(s)
- Digvijay Singh
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205, United States
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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36
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Hille F, Richter H, Wong SP, Bratovič M, Ressel S, Charpentier E. The Biology of CRISPR-Cas: Backward and Forward. Cell 2018. [DOI: 10.1016/j.cell.2017.11.032] [Citation(s) in RCA: 333] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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37
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van Erp PBG, Patterson A, Kant R, Berry L, Golden SM, Forsman BL, Carter J, Jackson RN, Bothner B, Wiedenheft B. Conformational Dynamics of DNA Binding and Cas3 Recruitment by the CRISPR RNA-Guided Cascade Complex. ACS Chem Biol 2018; 13:481-490. [PMID: 29035497 DOI: 10.1021/acschembio.7b00649] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Bacteria and archaea rely on CRISPR (clustered regularly interspaced short palindromic repeats) RNA-guided adaptive immune systems for sequence specific elimination of foreign nucleic acids. In Escherichia coli, short CRISPR-derived RNAs (crRNAs) assemble with Cas (CRISPR-associated) proteins into a 405-kilodalton multisubunit surveillance complex called Cascade (CRISPR-associated complex for antiviral defense). Cascade binds foreign DNA complementary to the crRNA guide and recruits Cas3, a trans-acting nuclease-helicase required for target degradation. Structural models of Cascade have captured static snapshots of the complex in distinct conformational states, but conformational dynamics of the 11-subunit surveillance complex have not been measured. Here, we use hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) to map conformational dynamics of Cascade onto the three-dimensional structure. New insights from structural dynamics are used to make functional predictions about the mechanisms of the R-loop coordination and Cas3 recruitment. We test these predictions in vivo and in vitro. Collectively, we show how mapping conformational dynamics onto static 3D-structures adds an additional dimension to the functional understanding of this biological machine.
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Affiliation(s)
| | | | | | | | | | | | | | - Ryan N. Jackson
- Department
of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
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38
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Gong S, Yu HH, Johnson KA, Taylor DW. DNA Unwinding Is the Primary Determinant of CRISPR-Cas9 Activity. Cell Rep 2018; 22:359-371. [PMID: 29320733 PMCID: PMC11151164 DOI: 10.1016/j.celrep.2017.12.041] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/16/2017] [Accepted: 12/11/2017] [Indexed: 12/26/2022] Open
Abstract
Bacterial adaptive immunity utilizes RNA-guided surveillance complexes comprising Cas proteins together with CRISPR RNAs (crRNAs) to target foreign nucleic acids for destruction. Cas9, a type II CRISPR-Cas effector complex, can be programed with a single-guide RNA that base pairs with the target strand of dsDNA, displacing the non-target strand to create an R-loop, where the HNH and the RuvC nuclease domains cleave opposing strands. While many structural and biochemical studies have shed light on the mechanism of Cas9 cleavage, a clear unifying model has yet to emerge. Our detailed kinetic characterization of the enzyme reveals that DNA binding is reversible, and R-loop formation is rate-limiting, occurring in two steps, one for each of the nuclease domains. The specificity constant for cleavage is determined through an induced-fit mechanism as the product of the equilibrium binding affinity for DNA and the rate of R-loop formation.
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Affiliation(s)
- Shanzhong Gong
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Helen Hong Yu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Kenneth A Johnson
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
| | - David W Taylor
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA.
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39
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Rao C, Chin D, Ensminger AW. Priming in a permissive type I-C CRISPR-Cas system reveals distinct dynamics of spacer acquisition and loss. RNA (NEW YORK, N.Y.) 2017; 23:1525-1538. [PMID: 28724535 PMCID: PMC5602111 DOI: 10.1261/rna.062083.117] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 07/08/2017] [Indexed: 06/07/2023]
Abstract
CRISPR-Cas is a bacterial and archaeal adaptive immune system that uses short, invader-derived sequences termed spacers to target invasive nucleic acids. Upon recognition of previously encountered invaders, the system can stimulate secondary spacer acquisitions, a process known as primed adaptation. Previous studies of primed adaptation have been complicated by intrinsically high interference efficiency of most systems against bona fide targets. As such, most primed adaptation to date has been studied within the context of imperfect sequence complementarity between spacers and targets. Here, we take advantage of a native type I-C CRISPR-Cas system in Legionella pneumophila that displays robust primed adaptation even within the context of a perfectly matched target. Using next-generation sequencing to survey acquired spacers, we observe strand bias and positional preference that are consistent with a 3'-5' translocation of the adaptation machinery. We show that spacer acquisition happens in a wide range of frequencies across the plasmid, including a remarkable hotspot that predominates irrespective of the priming strand. We systematically characterize protospacer sequence constraints in both adaptation and interference and reveal extensive flexibilities regarding the protospacer adjacent motif in both processes. Lastly, in a strain with a genetically truncated CRISPR array, we observe increased interference efficiency, which, when coupled with forced maintenance of a targeted plasmid, provides a useful experimental system to study spacer loss. Based on these observations, we propose that the Legionella pneumophila type I-C system represents a powerful model to study primed adaptation and the interplay between CRISPR interference and adaptation.
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Affiliation(s)
- Chitong Rao
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Denny Chin
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Alexander W Ensminger
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
- Public Health Ontario, Toronto, Ontario M5G 1M1, Canada
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40
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Musharova O, Klimuk E, Datsenko KA, Metlitskaya A, Logacheva M, Semenova E, Severinov K, Savitskaya E. Spacer-length DNA intermediates are associated with Cas1 in cells undergoing primed CRISPR adaptation. Nucleic Acids Res 2017; 45:3297-3307. [PMID: 28204574 PMCID: PMC5389516 DOI: 10.1093/nar/gkx097] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 02/06/2017] [Indexed: 01/16/2023] Open
Abstract
During primed CRISPR adaptation spacers are preferentially selected from DNA recognized by CRISPR interference machinery, which in the case of Type I CRISPR-Cas systems consists of CRISPR RNA (crRNA) bound effector Cascade complex that locates complementary targets, and Cas3 executor nuclease/helicase. A complex of Cas1 and Cas2 proteins is capable of inserting new spacers in the CRISPR array. Here, we show that in Escherichia coli cells undergoing primed adaptation, spacer-sized fragments of foreign DNA are associated with Cas1. Based on sensitivity to digestion with nucleases, the associated DNA is not in a standard double-stranded state. Spacer-sized fragments are cut from one strand of foreign DNA in Cas1- and Cas3-dependent manner. These fragments are generated from much longer S1-nuclease sensitive fragments of foreign DNA that require Cas3 for their production. We propose that in the course of CRISPR interference Cas3 generates fragments of foreign DNA that are recognized by the Cas1-Cas2 adaptation complex, which excises spacer-sized fragments and channels them for insertion into CRISPR array.
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Affiliation(s)
- Olga Musharova
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Evgeny Klimuk
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Kirill A Datsenko
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | - Maria Logacheva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ekaterina Semenova
- Waksman Institute, Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Konstantin Severinov
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.,Waksman Institute, Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Ekaterina Savitskaya
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
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41
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Jung C, Hawkins JA, Jones SK, Xiao Y, Rybarski JR, Dillard KE, Hussmann J, Saifuddin FA, Savran CA, Ellington AD, Ke A, Press WH, Finkelstein IJ. Massively Parallel Biophysical Analysis of CRISPR-Cas Complexes on Next Generation Sequencing Chips. Cell 2017; 170:35-47.e13. [PMID: 28666121 DOI: 10.1016/j.cell.2017.05.044] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/23/2017] [Accepted: 05/26/2017] [Indexed: 12/26/2022]
Abstract
CRISPR-Cas nucleoproteins target foreign DNA via base pairing with a crRNA. However, a quantitative description of protein binding and nuclease activation at off-target DNA sequences remains elusive. Here, we describe a chip-hybridized association-mapping platform (CHAMP) that repurposes next-generation sequencing chips to simultaneously measure the interactions between proteins and ∼107 unique DNA sequences. Using CHAMP, we provide the first comprehensive survey of DNA recognition by a type I-E CRISPR-Cas (Cascade) complex and Cas3 nuclease. Analysis of mutated target sequences and human genomic DNA reveal that Cascade recognizes an extended protospacer adjacent motif (PAM). Cascade recognizes DNA with a surprising 3-nt periodicity. The identity of the PAM and the PAM-proximal nucleotides control Cas3 recruitment by releasing the Cse1 subunit. These findings are used to develop a model for the biophysical constraints governing off-target DNA binding. CHAMP provides a framework for high-throughput, quantitative analysis of protein-DNA interactions on synthetic and genomic DNA. PAPERCLIP.
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Affiliation(s)
- Cheulhee Jung
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - John A Hawkins
- Institute for Computational Engineering and Science, The University of Texas at Austin, Austin, TX 78712, USA
| | - Stephen K Jones
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - James R Rybarski
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Kaylee E Dillard
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jeffrey Hussmann
- Institute for Computational Engineering and Science, The University of Texas at Austin, Austin, TX 78712, USA
| | - Fatema A Saifuddin
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Cagri A Savran
- School of Mechanical Engineering, Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA
| | - Andrew D Ellington
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - William H Press
- Institute for Computational Engineering and Science, The University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA; Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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42
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Xiao Y, Luo M, Hayes RP, Kim J, Ng S, Ding F, Liao M, Ke A. Structure Basis for Directional R-loop Formation and Substrate Handover Mechanisms in Type I CRISPR-Cas System. Cell 2017; 170:48-60.e11. [PMID: 28666122 DOI: 10.1016/j.cell.2017.06.012] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/27/2017] [Accepted: 06/08/2017] [Indexed: 01/06/2023]
Abstract
Type I CRISPR systems feature a sequential dsDNA target searching and degradation process, by crRNA-displaying Cascade and nuclease-helicase fusion enzyme Cas3, respectively. Here we present two cryo-EM snapshots of the Thermobifida fusca type I-E Cascade: (1) unwinding 11 bp of dsDNA at the seed-sequence region to scout for sequence complementarity, and (2) further unwinding of the entire protospacer to form a full R-loop. These structures provide the much-needed temporal and spatial resolution to resolve key mechanistic steps leading to Cas3 recruitment. In the early steps, PAM recognition causes severe DNA bending, leading to spontaneous DNA unwinding to form a seed-bubble. The full R-loop formation triggers conformational changes in Cascade, licensing Cas3 to bind. The same process also generates a bulge in the non-target DNA strand, enabling its handover to Cas3 for cleavage. The combination of both negative and positive checkpoints ensures stringent yet efficient target degradation in type I CRISPR-Cas systems.
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Affiliation(s)
- Yibei Xiao
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Min Luo
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA
| | - Robert P Hayes
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Jonathan Kim
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Sherwin Ng
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Fang Ding
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, SGM 509, Boston, MA 02115, USA.
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
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43
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CRISPR-Cas adaptive immunity and the three Rs. Biosci Rep 2017; 37:BSR20160297. [PMID: 28674106 PMCID: PMC5518543 DOI: 10.1042/bsr20160297] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/26/2017] [Accepted: 07/03/2017] [Indexed: 12/11/2022] Open
Abstract
In this summary, we focus on fundamental biology of Clustered Regularly Interspersed Short Palindromic Repeats (CRISPR)-Cas (CRISPR-associated proteins) adaptive immunity in bacteria. Emphasis is placed on emerging information about functional interplay between Cas proteins and proteins that remodel DNA during homologous recombination (HR), DNA replication or DNA repair. We highlight how replication forks may act as ‘trigger points’ for CRISPR adaptation events, and the potential for cascade-interference complexes to act as precise roadblocks in DNA replication by an invader MGE (mobile genetic element), without the need for DNA double-strand breaks.
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44
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Celaya G, Perales-Calvo J, Muga A, Moro F, Rodriguez-Larrea D. Label-Free, Multiplexed, Single-Molecule Analysis of Protein-DNA Complexes with Nanopores. ACS NANO 2017; 11:5815-5825. [PMID: 28530800 DOI: 10.1021/acsnano.7b01434] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Protein interactions with specific DNA sequences are crucial in the control of gene expression and the regulation of replication. Single-molecule methods offer excellent capabilities to unravel the mechanism and kinetics of these interactions. Here, we develop a nanopore approach where a target DNA sequence is contained in a hairpin followed by a ssDNA. This system allows DNA-protein complexes to be distinguished from bare DNA molecules as they are pulled through a single nanopore detector, providing both equilibrium and kinetic information. We show that this approach can be used to test the inhibitory effect of small molecules on complex formation and their mechanisms of action. In a proof of concept, we use DNAs with different sequence patterns to probe the ability of the nanopore to distinguish the effects of an inhibitor in a complex mixture of target DNAs and proteins. We anticipate that the use of this technology with arrays of thousands of nanopores will contribute to the development of transcription factor binding inhibitors.
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Affiliation(s)
- Garbiñe Celaya
- Biofisika Institute (CSIC, UPV/EHU) , Department of Biochemistry and Molecular Biology (UPV/EHU), Leioa 48940, Spain
| | - Judit Perales-Calvo
- Biofisika Institute (CSIC, UPV/EHU) , Department of Biochemistry and Molecular Biology (UPV/EHU), Leioa 48940, Spain
| | - Arturo Muga
- Biofisika Institute (CSIC, UPV/EHU) , Department of Biochemistry and Molecular Biology (UPV/EHU), Leioa 48940, Spain
| | - Fernando Moro
- Biofisika Institute (CSIC, UPV/EHU) , Department of Biochemistry and Molecular Biology (UPV/EHU), Leioa 48940, Spain
| | - David Rodriguez-Larrea
- Biofisika Institute (CSIC, UPV/EHU) , Department of Biochemistry and Molecular Biology (UPV/EHU), Leioa 48940, Spain
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45
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Jackson RN, van Erp PB, Sternberg SH, Wiedenheft B. Conformational regulation of CRISPR-associated nucleases. Curr Opin Microbiol 2017. [PMID: 28646675 DOI: 10.1016/j.mib.2017.05.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Adaptive immune systems in bacteria and archaea rely on small CRISPR-derived RNAs (crRNAs) to guide specialized nucleases to foreign nucleic acids. The activation of these nucleases is controlled by a series of molecular checkpoints that ensure precise cleavage of nucleic acid targets, while minimizing toxic off-target cleavage events. In this review, we highlight recent advances in understanding regulatory mechanisms responsible for controlling the activation of these nucleases and identify emerging regulatory themes conserved across diverse CRISPR systems.
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Affiliation(s)
- Ryan N Jackson
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, United States.
| | - Paul Bg van Erp
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States.
| | | | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, United States.
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46
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Cas1 and the Csy complex are opposing regulators of Cas2/3 nuclease activity. Proc Natl Acad Sci U S A 2017; 114:E5113-E5121. [PMID: 28438998 DOI: 10.1073/pnas.1616395114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The type I-F CRISPR adaptive immune system in Pseudomonas aeruginosa (PA14) consists of two CRISPR loci and six CRISPR-associated (cas) genes. Type I-F systems rely on a CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-acting nuclease (i.e., Cas2/3) for target degradation. In most type I systems, Cas2 and Cas3 are separate proteins involved in adaptation and interference, respectively. However, in I-F systems, these proteins are fused into a single polypeptide. Here we use biochemical and structural methods to show that two molecules of Cas2/3 assemble with four molecules of Cas1 (Cas2/32:Cas14) into a four-lobed propeller-shaped structure, where the two Cas2 domains form a central hub (twofold axis of symmetry) flanked by two Cas1 lobes and two Cas3 lobes. We show that the Cas1 subunits repress Cas2/3 nuclease activity and that foreign DNA recognition by the Csy complex activates Cas2/3, resulting in bidirectional degradation of DNA targets. Collectively, this work provides a structure of the Cas1-2/3 complex and explains how Cas1 and the target-bound Csy complex play opposing roles in the regulation of Cas2/3 nuclease activity.
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47
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Jackson SA, McKenzie RE, Fagerlund RD, Kieper SN, Fineran PC, Brouns SJJ. CRISPR-Cas: Adapting to change. Science 2017; 356:356/6333/eaal5056. [PMID: 28385959 DOI: 10.1126/science.aal5056] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bacteria and archaea are engaged in a constant arms race to defend against the ever-present threats of viruses and invasion by mobile genetic elements. The most flexible weapons in the prokaryotic defense arsenal are the CRISPR-Cas adaptive immune systems. These systems are capable of selective identification and neutralization of foreign DNA and/or RNA. CRISPR-Cas systems rely on stored genetic memories to facilitate target recognition. Thus, to keep pace with a changing pool of hostile invaders, the CRISPR memory banks must be regularly updated with new information through a process termed CRISPR adaptation. In this Review, we outline the recent advances in our understanding of the molecular mechanisms governing CRISPR adaptation. Specifically, the conserved protein machinery Cas1-Cas2 is the cornerstone of adaptive immunity in a range of diverse CRISPR-Cas systems.
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Affiliation(s)
- Simon A Jackson
- Department of Microbiology and Immunology, University of Otago, Post Office Box 56, Dunedin 9054, New Zealand
| | - Rebecca E McKenzie
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, Netherlands
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, Post Office Box 56, Dunedin 9054, New Zealand
| | - Sebastian N Kieper
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, Netherlands
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, Post Office Box 56, Dunedin 9054, New Zealand. .,Bio-Protection Research Centre, University of Otago, Post Office Box 56, Dunedin 9054, New Zealand
| | - Stan J J Brouns
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, Netherlands. .,Laboratory of Microbiology, Wageningen University, Wageningen, Netherlands
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48
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Rutkauskas M, Krivoy A, Szczelkun MD, Rouillon C, Seidel R. Single-Molecule Insight Into Target Recognition by CRISPR-Cas Complexes. Methods Enzymol 2016; 582:239-273. [PMID: 28062037 DOI: 10.1016/bs.mie.2016.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ribonucleoprotein (RNP) complexes from CRISPR-Cas systems have attracted enormous interest since they can be easily and flexibly reprogrammed to target any desired locus for genome engineering and gene regulation applications. Basis for the programmability is a short RNA (crRNA) inside these complexes that recognizes the target nucleic acid by base pairing. For CRISPR-Cas systems that target double-stranded DNA this results in local DNA unwinding and formation of a so-called R-loop structure. Here we provide an overview how this target recognition mechanism can be dissected in great detail at the level of a single molecule. Specifically, we demonstrate how magnetic tweezers are applied to measure the local DNA unwinding at the target in real time. To this end we introduce the technique and the measurement principle. By studying modifications of the consensus target sequence, we show how different sequence elements contribute to the target recognition mechanism. From these data, a unified target recognition mechanism can be concluded for the RNPs Cascade and Cas9 from types I and II CRISPR-Cas systems. R-loop formation is hereby initiated on the target at an upstream element, called protospacer adjacent motif (PAM), from which the R-loop structure zips directionally toward the PAM-distal end of the target. At mismatch positions, the R-loop propagation stalls and further propagation competes with collapse of the structure. Upon full R-loop zipping conformational changes within the RNPs trigger degradation of the DNA target. This represents a shared labor mechanism in which zipping between nucleic acid strands is the actual target recognition mechanism while sensing of the R-loop arrival at the PAM-distal end just verifies the success of the full zipping.
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Affiliation(s)
- M Rutkauskas
- Molecular Biophysics Group, Institute for Experimental Physics I, Universität Leipzig, Leipzig, Germany
| | - A Krivoy
- Molecular Biophysics Group, Institute for Experimental Physics I, Universität Leipzig, Leipzig, Germany; Skolkovo Institute of Science and Technology, Skolkovo, Russia
| | - M D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - C Rouillon
- Molecular Biophysics Group, Institute for Experimental Physics I, Universität Leipzig, Leipzig, Germany.
| | - R Seidel
- Molecular Biophysics Group, Institute for Experimental Physics I, Universität Leipzig, Leipzig, Germany.
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49
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Westra ER, Dowling AJ, Broniewski JM, van Houte S. Evolution and Ecology of CRISPR. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2016. [DOI: 10.1146/annurev-ecolsys-121415-032428] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Edze R. Westra
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Andrea J. Dowling
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Jenny M. Broniewski
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Stineke van Houte
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
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50
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Xue C, Whitis NR, Sashital DG. Conformational Control of Cascade Interference and Priming Activities in CRISPR Immunity. Mol Cell 2016; 64:826-834. [PMID: 27871367 DOI: 10.1016/j.molcel.2016.09.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/11/2016] [Accepted: 08/22/2016] [Indexed: 10/20/2022]
Abstract
During type I-E CRISPR-Cas immunity, the Cascade surveillance complex utilizes CRISPR-derived RNAs to target complementary invasive DNA for destruction. When invader mutation blocks this interference activity, Cascade instead triggers rapid primed adaptation against the invader. The molecular basis for this dual Cascade activity is poorly understood. Here we show that the conformation of the Cse1 subunit controls Cascade activity. Using FRET, we find that Cse1 exists in a dynamic equilibrium between "open" and "closed" conformations, and the extent to which the open conformation is favored directly correlates with the attenuation of interference and relative increase in priming activity upon target mutation. Additionally, the Cse1 L1 motif modulates Cascade activity by stabilizing the closed conformation. L1 mutations promote the open conformation and switch immune response from interference to priming. Our results demonstrate that Cascade conformation controls the functional outcome of target recognition, enabling tunable CRISPR immune response to combat invader evolution.
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Affiliation(s)
- Chaoyou Xue
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Ames, IA 50011, USA
| | - Natalie R Whitis
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Ames, IA 50011, USA
| | - Dipali G Sashital
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Ames, IA 50011, USA.
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