1
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Wang X, Leptihn S. Defense and anti-defense mechanisms of bacteria and bacteriophages. J Zhejiang Univ Sci B 2024; 25:181-196. [PMID: 38453634 PMCID: PMC10918411 DOI: 10.1631/jzus.b2300101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 06/24/2023] [Indexed: 03/09/2024]
Abstract
In the post-antibiotic era, the overuse of antimicrobials has led to a massive increase in antimicrobial resistance, leaving medical doctors few or no treatment options to fight infections caused by superbugs. The use of bacteriophages is a promising alternative to treat infections, supplementing or possibly even replacing antibiotics. Using phages for therapy is possible, since these bacterial viruses can kill bacteria specifically, causing no harm to the normal flora. However, bacteria have developed a multitude of sophisticated and complex ways to resist infection by phages, including abortive infection and the clustered regularly interspersed short palindromic repeats (CRISPR)/CRISPR-associated (Cas) system. Phages also can evolve and acquire new anti-defense strategies to continue predation. An in-depth exploration of both defense and anti-defense mechanisms would contribute to optimizing phage therapy, while we would also gain novel insights into the microbial world. In this paper, we summarize recent research on bacterial phage resistance and phage anti-defense mechanisms, as well as collaborative win-win systems involving both virus and host.
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Affiliation(s)
- Xiaoqing Wang
- School of Medicine, Lishui University, Lishui 323000, China.
| | - Sebastian Leptihn
- University of Edinburgh Medical School, Biomedical Sciences, College of Medicine & Veterinary Medicine, The University of Edinburgh, Edinburgh EH8 9JZ, UK.
- HMU Health and Medical University, Am Anger 64/73- 99084 Erfurt, Germany.
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2
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Forsberg KJ. Anti-CRISPR Discovery: Using Magnets to Find Needles in Haystacks. J Mol Biol 2023; 435:167952. [PMID: 36638909 PMCID: PMC10073268 DOI: 10.1016/j.jmb.2023.167952] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/22/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
CRISPR-Cas immune systems in bacteria and archaea protect against viral infection, which has spurred viruses to develop dedicated inhibitors of these systems called anti-CRISPRs (Acrs). Like most host-virus arms races, many diverse examples of these immune and counter-immune proteins are encoded by the genomes of bacteria, archaea, and their viruses. For the case of Acrs, it is almost certain that just a small minority of nature's true diversity has been described. In this review, I discuss the various approaches used to identify these Acrs and speculate on the future for Acr discovery. Because Acrs can determine infection outcomes in nature and regulate CRISPR-Cas activities in applied settings, they have a dual importance to both host-virus conflicts and emerging biotechnologies. Thus, revealing the largely hidden world of Acrs should provide important lessons in microbiology that have the potential to ripple far beyond the field.
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Affiliation(s)
- Kevin J Forsberg
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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3
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Yin P, Zhang Y, Yang L, Feng Y. Non-canonical inhibition strategies and structural basis of anti-CRISPR proteins targeting type I CRISPR-Cas systems. J Mol Biol 2023; 435:167996. [PMID: 36754343 DOI: 10.1016/j.jmb.2023.167996] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/10/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023]
Abstract
Mobile genetic elements (MGEs) such as bacteriophages and their host prokaryotes are trapped in an eternal battle against each other. To cope with foreign infection, bacteria and archaea have evolved multiple immune strategies, out of which CRISPR-Cas system is up to now the only discovered adaptive system in prokaryotes. Despite the fact that CRISPR-Cas system provides powerful and delicate protection against MGEs, MGEs have also evolved anti-CRISPR proteins (Acrs) to counteract the CRISPR-Cas immune defenses. To date, 46 families of Acrs targeting type I CRISPR-Cas system have been characterized, out of which structure information of 21 families have provided insights on their inhibition strategies. Here, we review the non-canonical inhibition strategies adopted by Acrs targeting type I CRISPR-Cas systems based on their structure information by incorporating the most recent advances in this field, and discuss our current understanding and future perspectives. The delicate interplay between type I CRISPR-Cas systems and their Acrs provides us with important insights into the ongoing fierce arms race between prokaryotic hosts and their predators.
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Affiliation(s)
- Peipei Yin
- Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, College of Chemical and Biological Engineering, Yichun University, Yichun 336000, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Lingguang Yang
- Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, College of Chemical and Biological Engineering, Yichun University, Yichun 336000, China
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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4
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Zakrzewska M, Burmistrz M. Mechanisms regulating the CRISPR-Cas systems. Front Microbiol 2023; 14:1060337. [PMID: 36925473 PMCID: PMC10013973 DOI: 10.3389/fmicb.2023.1060337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/10/2023] [Indexed: 03/08/2023] Open
Abstract
The CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats- CRISPR associated proteins) is a prokaryotic system that enables sequence specific recognition and cleavage of nucleic acids. This is possible due to cooperation between CRISPR array which contains short fragments of DNA called spacers that are complimentary to the targeted nucleic acid and Cas proteins, which take part in processes of: acquisition of new spacers, processing them into their functional form as well as recognition and cleavage of targeted nucleic acids. The primary role of CRISPR-Cas systems is to provide their host with an adaptive and hereditary immunity against exogenous nucleic acids. This system is present in many variants in both Bacteria and Archea. Due to its modular structure, and programmability CRISPR-Cas system become attractive tool for modern molecular biology. Since their discovery and implementation, the CRISPR-Cas systems revolutionized areas of gene editing and regulation of gene expression. Although our knowledge on how CRISPR-Cas systems work has increased rapidly in recent years, there is still little information on how these systems are controlled and how they interact with other cellular mechanisms. Such regulation can be the result of both auto-regulatory mechanisms as well as exogenous proteins of phage origin. Better understanding of these interaction networks would be beneficial for optimization of current and development of new CRISPR-Cas-based tools. In this review we summarize current knowledge on the various molecular mechanisms that affect activity of CRISPR-Cas systems.
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Affiliation(s)
- Marta Zakrzewska
- Department of Environmental Microbiology and Biotechnology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland.,Department of Molecular Microbiology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Michal Burmistrz
- Department of Molecular Microbiology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, Warsaw, Poland
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5
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Patterson A, White A, Waymire E, Fleck S, Golden S, Wilkinson RA, Wiedenheft B, Bothner B. Anti-CRISPR proteins function through thermodynamic tuning and allosteric regulation of CRISPR RNA-guided surveillance complex. Nucleic Acids Res 2022; 50:11243-11254. [PMID: 36215034 DOI: 10.1093/nar/gkac841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 09/14/2022] [Accepted: 10/07/2022] [Indexed: 11/13/2022] Open
Abstract
CRISPR RNA-guided detection and degradation of foreign DNA is a dynamic process. Viruses can interfere with this cellular defense by expressing small proteins called anti-CRISPRs. While structural models of anti-CRISPRs bound to their target complex provide static snapshots that inform mechanism, the dynamics and thermodynamics of these interactions are often overlooked. Here, we use hydrogen deuterium exchange-mass spectrometry (HDX-MS) and differential scanning fluorimetry (DSF) experiments to determine how anti-CRISPR binding impacts the conformational landscape of the type IF CRISPR RNA guided surveillance complex (Csy) upon binding of two different anti-CRISPR proteins (AcrIF9 and AcrIF2). The results demonstrate that AcrIF2 binding relies on enthalpic stabilization, whereas AcrIF9 uses an entropy driven reaction to bind the CRISPR RNA-guided surveillance complex. Collectively, this work reveals the thermodynamic basis and mechanistic versatility of anti-CRISPR-mediated immune suppression. More broadly, this work presents a striking example of how allosteric effectors are employed to regulate nucleoprotein complexes.
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Affiliation(s)
- Angela Patterson
- Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, USA
| | - Aidan White
- Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, USA
| | - Elizabeth Waymire
- Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, USA
| | - Sophie Fleck
- Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, USA
| | - Sarah Golden
- Microbiology and Cell Biology Department, Montana State University, Bozeman, MT 59717, USA
| | - Royce A Wilkinson
- Microbiology and Cell Biology Department, Montana State University, Bozeman, MT 59717, USA
| | - Blake Wiedenheft
- Microbiology and Cell Biology Department, Montana State University, Bozeman, MT 59717, USA
| | - Brian Bothner
- Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, USA
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6
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Gao Z, Zhang L, Ge Z, Wang H, Yue Y, Jiang Z, Wang X, Xu C, Zhang Y, Yang M, Feng Y. Anti-CRISPR protein AcrIF4 inhibits the type I-F CRISPR-Cas surveillance complex by blocking nuclease recruitment and DNA cleavage. J Biol Chem 2022; 298:102575. [PMID: 36209819 PMCID: PMC9637919 DOI: 10.1016/j.jbc.2022.102575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/28/2022] [Accepted: 10/01/2022] [Indexed: 11/25/2022] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system provides prokaryotes with protection against mobile genetic elements such as phages. In turn, phages deploy anti-CRISPR (Acr) proteins to evade this immunity. AcrIF4, an Acr targeting the type I-F CRISPR-Cas system, has been reported to bind the crRNA-guided surveillance (Csy) complex. However, it remains controversial whether AcrIF4 inhibits target DNA binding to the Csy complex. Here, we present structural and mechanistic studies into AcrIF4, exploring its unique anti-CRISPR mechanism. While the Csy-AcrIF4 complex displays decreased affinity for target DNA, it is still able to bind the DNA. Our structural and functional analyses of the Csy-AcrIF4-dsDNA complex revealed that AcrIF4 binding prevents rotation of the helical bundle of the Cas8f subunit induced by dsDNA binding, therefore resulting in failure of nuclease Cas2/3 recruitment and DNA cleavage. Overall, our study provides an interesting example of attack on the nuclease recruitment event by an Acr, but not conventional mechanisms of blocking binding of target DNA.
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Affiliation(s)
- Zhengyu Gao
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Laixing Zhang
- Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Zihao Ge
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Hao Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Yourun Yue
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Zhuobing Jiang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Xin Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Chenying Xu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China,For correspondence: Yue Feng; Maojun Yang; Yi Zhang
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China,For correspondence: Yue Feng; Maojun Yang; Yi Zhang
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China,For correspondence: Yue Feng; Maojun Yang; Yi Zhang
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7
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Mukherjee IA, Gabel C, Noinaj N, Bondy-Denomy J, Chang L. Structural basis of AcrIF24 as an anti-CRISPR protein and transcriptional suppressor. Nat Chem Biol 2022; 18:1417-1424. [PMID: 36163386 PMCID: PMC9691602 DOI: 10.1038/s41589-022-01137-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 08/08/2022] [Indexed: 11/09/2022]
Abstract
Anti-CRISPR (Acr) proteins are encoded by phages to inactivate CRISPR-Cas systems of bacteria and archaea and are used to enhance the CRISPR toolbox for genome editing. Here we report the structure and mechanism of AcrIF24, an Acr protein that inhibits the type I-F CRISPR-Cas system from Pseudomonas aeruginosa. AcrIF24 is a homodimer that associates with two copies of the surveillance complex (Csy) and prevents the hybridization between CRISPR RNA and target DNA. Furthermore, AcrIF24 functions as an anti-CRISPR-associated (Aca) protein to repress the transcription of the acrIF23-acrIF24 operon. Alone or in complex with Csy, AcrIF24 is capable of binding to the acrIF23-acrIF24 promoter DNA with nanomolar affinity. The structure of a Csy-AcrIF24-promoter DNA complex at 2.7 Å reveals the mechanism for transcriptional suppression. Our results reveal that AcrIF24 functions as an Acr-Aca fusion protein, and they extend understanding of the diverse mechanisms used by Acr proteins.
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Affiliation(s)
| | - Clinton Gabel
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Nicholas Noinaj
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.,Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, USA.,Innovative Genomics Institute, Berkeley, CA, USA
| | - Leifu Chang
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA. .,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, USA.
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8
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Disarming of type I-F CRISPR-Cas surveillance complex by anti-CRISPR proteins AcrIF6 and AcrIF9. Sci Rep 2022; 12:15548. [PMID: 36109551 PMCID: PMC9478129 DOI: 10.1038/s41598-022-19797-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 09/05/2022] [Indexed: 11/30/2022] Open
Abstract
CRISPR-Cas systems are prokaryotic adaptive immune systems that protect against phages and other invading nucleic acids. The evolutionary arms race between prokaryotes and phages gave rise to phage anti-CRISPR (Acr) proteins that act as a counter defence against CRISPR-Cas systems by inhibiting the effector complex. Here, we used a combination of bulk biochemical experiments, X-ray crystallography and single-molecule techniques to explore the inhibitory activity of AcrIF6 and AcrIF9 proteins against the type I-F CRISPR-Cas system from Aggregatibacter actinomycetemcomitans (Aa). We showed that AcrIF6 and AcrIF9 proteins hinder Aa-Cascade complex binding to target DNA. We solved a crystal structure of Aa1-AcrIF9 protein, which differ from other known AcrIF9 proteins by an additional structurally important loop presumably involved in the interaction with Cascade. We revealed that AcrIF9 association with Aa-Cascade promotes its binding to off-target DNA sites, which facilitates inhibition of CRISPR-Cas protection.
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9
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Ren J, Wang H, Yang L, Li F, Wu Y, Luo Z, Chen Z, Zhang Y, Feng Y. Structural and mechanistic insights into the inhibition of type I-F CRISPR-Cas system by anti-CRISPR protein AcrIF23. J Biol Chem 2022; 298:102124. [PMID: 35697070 PMCID: PMC9270243 DOI: 10.1016/j.jbc.2022.102124] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 11/29/2022] Open
Abstract
Prokaryotes evolved CRISPR and CRISPR-associated (Cas) proteins as a kind of adaptive immune defense against mobile genetic elements (MGEs) including harmful phages. To counteract this defense, many MGEs in turn encode anti-CRISPR proteins (Acrs) to inactivate the CRISPR-Cas system. While multiple mechanisms of Acrs have been uncovered, it remains unknown whether other mechanisms are also utilized by uncharacterized Acrs. Here, we report a novel mechanism adopted by recently identified AcrIF23. We show that AcrIF23 interacts with the Cas2/3 helicase-nuclease in the type I-F CRISPR-Cas system, similar to AcrIF3. The structure of AcrIF23 demonstrated a novel fold and structure-based mutagenesis identified a surface region of AcrIF23 involved in both Cas2/3-binding and its inhibition capacity. Unlike AcrIF3, however, we found AcrIF23 only potently inhibits the DNA cleavage activity of Cas2/3, but does not hinder the recruitment of Cas2/3 to the CRISPR RNA (crRNA)-guided surveillance complex (the Csy complex). Also in contrast to AcrIF3 which hinders substrate DNA recognition by Cas2/3, we show AcrIF23 promotes DNA binding to Cas2/3. Taken together, our study identifies a novel anti-CRISPR mechanism used by AcrIF23 and highlights the diverse mechanisms adopted by Acrs.
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Affiliation(s)
- Junhui Ren
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hao Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Lingguang Yang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China; Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, Department of Chemistry and Bioengineering, Yichun University, Yichun 336000, China
| | - Feixue Li
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yao Wu
- State Key Laboratory of Plant Genomic, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhipu Luo
- Institute of Molecular Enzymology, School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, Jiangsu, China
| | - Zeliang Chen
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China; Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Liaoning Province, Shenyang 110866, China.
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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10
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Yang L, Zhang L, Yin P, Ding H, Xiao Y, Zeng J, Wang W, Zhou H, Wang Q, Zhang Y, Chen Z, Yang M, Feng Y. Insights into the inhibition of type I-F CRISPR-Cas system by a multifunctional anti-CRISPR protein AcrIF24. Nat Commun 2022; 13:1931. [PMID: 35411005 PMCID: PMC9001735 DOI: 10.1038/s41467-022-29581-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 03/16/2022] [Indexed: 11/18/2022] Open
Abstract
CRISPR-Cas systems are prokaryotic adaptive immune systems and phages use anti-CRISPR proteins (Acrs) to counteract these systems. Here, we report the structures of AcrIF24 and its complex with the crRNA-guided surveillance (Csy) complex. The HTH motif of AcrIF24 can bind the Acr promoter region and repress its transcription, suggesting its role as an Aca gene in self-regulation. AcrIF24 forms a homodimer and further induces dimerization of the Csy complex. Apart from blocking the hybridization of target DNA to the crRNA, AcrIF24 also induces the binding of non-sequence-specific dsDNA to the Csy complex, similar to AcrIF9, although this binding seems to play a minor role in AcrIF24 inhibitory capacity. Further structural and biochemical studies of the Csy-AcrIF24-dsDNA complexes and of AcrIF24 mutants reveal that the HTH motif of AcrIF24 and the PAM recognition loop of the Csy complex are structural elements essential for this non-specific dsDNA binding. Moreover, AcrIF24 and AcrIF9 display distinct characteristics in inducing non-specific DNA binding. Together, our findings highlight a multifunctional Acr and suggest potential wide distribution of Acr-induced non-specific DNA binding. Phages use anti-CRISPR proteins (Acrs) to counteract the bacterial CRISPR-Cas systems. Here, the authors characterize AcrIF24, which functions as an Aca (Acr-associated) to repress and regulate its own transcription, dimerizes the Csy complex, blocks the hybridization of target DNA, and tethers non-sequence-specific DNA to the Csy complex.
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11
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AcrIF5 specifically targets DNA-bound CRISPR-Cas surveillance complex for inhibition. Nat Chem Biol 2022; 18:670-677. [PMID: 35301482 DOI: 10.1038/s41589-022-00995-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 02/10/2022] [Indexed: 01/04/2023]
Abstract
CRISPR-Cas systems are prokaryotic antiviral systems, and phages use anti-CRISPR proteins (Acrs) to inactivate these systems. Here we present structural and functional analyses of AcrIF5, exploring its unique anti-CRISPR mechanism. AcrIF5 shows binding specificity only for the target DNA-bound form of the crRNA-guided surveillance (Csy) complex, but not the apo Csy complex from the type I-F CRISPR-Cas system. We solved the structure of the Csy-dsDNA-AcrIF5 complex, revealing that the conformational changes of the Csy complex caused by dsDNA binding dictate the binding specificity for the Csy-dsDNA complex by AcrIF5. Mechanistically, five AcrIF5 molecules bind one Csy-dsDNA complex, which destabilizes the helical bundle domain of Cas8f, thus preventing subsequent Cas2/3 recruitment. AcrIF5 exists in symbiosis with AcrIF3, which blocks Cas2/3 recruitment. This attack on the recruitment event stands in contrast to the conventional mechanisms of blocking binding of target DNA. Overall, our study reveals an unprecedented mechanism of CRISPR-Cas inhibition by AcrIF5.
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12
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Wang H, Gao T, Zhou Y, Ren J, Guo J, Zeng J, Xiao Y, Zhang Y, Feng Y. Mechanistic insights into the inhibition of the CRISPR-Cas Surveillance Complex by anti-CRISPR protein AcrIF13. J Biol Chem 2022; 298:101636. [PMID: 35085557 PMCID: PMC8857482 DOI: 10.1016/j.jbc.2022.101636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 11/09/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins provide prokaryotes with nucleic acid–based adaptive immunity against infections of mobile genetic elements, including phages. To counteract this immune process, phages have evolved various anti-CRISPR (Acr) proteins which deactivate CRISPR-Cas–based immunity. However, the mechanisms of many of these Acr-mediated inhibitions are not clear. Here, we report the crystal structure of AcrIF13 and explore its inhibition mechanism. The structure of AcrIF13 is unique and displays a negatively charged surface. Additionally, biochemical studies identified that AcrIF13 interacts with the type I-F CRISPR-Cas surveillance complex (Csy complex) to block target DNA recognition and that the Cas5f-8f tail and Cas7.6f subunit of the Csy complex are specific binding targets of AcrIF13. Further mutational studies demonstrated that several negatively charged residues of AcrIF13 and positively charged residues of Cas8f and Cas7f of the Csy complex are involved in AcrIF13–Csy binding. Together, our findings provide mechanistic insights into the inhibition mechanism of AcrIF13 and further suggest the prevalence of the function of Acr proteins as DNA mimics.
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Affiliation(s)
- Hao Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Teng Gao
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Yu Zhou
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Junhui Ren
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Junhua Guo
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Jianwei Zeng
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Yu Xiao
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China.
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13
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Vyas P, Harish. Anti-CRISPR proteins as a therapeutic agent against drug-resistant bacteria. Microbiol Res 2022; 257:126963. [PMID: 35033831 DOI: 10.1016/j.micres.2022.126963] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 02/08/2023]
Abstract
The continuous deployment of various antibiotics to treat multiple serious bacterial infections leads to multidrug resistance among the bacterial population. It has failed the standard treatment strategies through different antibacterial agents and serves as a significant threat to public health worldwide at devastating levels. The discovery of anti-CRISPR proteins catches the interest of researchers around the world as a promising therapeutic agent against drug-resistant bacteria. Anti-CRISPR proteins are known to inhibit bacterial CRISPR-Cas defense systems in multiple possible ways. The CRISPR-Cas nucleoprotein assembly provides adaptive immunity in bacteria against diverse categories of phage infections. Parallelly, phages also try to break the CRISPR-Cas barrier by producing anti-CRISPR proteins, leading to growth inhibition and bacterial lysis. This review begins with a brief description of the bacterial CRISPR-Cas system, followed by a detailed portrayal of anti-CRISPR proteins, including their discovery and evolution, mechanism of action, regulation of expression, and potential applications in the healthcare sector as an alternative therapeutic strategy to combat severe bacterial infections.
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Affiliation(s)
- Pallavi Vyas
- Plant Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University, Udaipur, 313 001, Rajasthan, India
| | - Harish
- Plant Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University, Udaipur, 313 001, Rajasthan, India.
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14
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Alternative functions of CRISPR-Cas systems in the evolutionary arms race. Nat Rev Microbiol 2022; 20:351-364. [PMID: 34992260 DOI: 10.1038/s41579-021-00663-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2021] [Indexed: 12/14/2022]
Abstract
CRISPR-Cas systems of bacteria and archaea comprise chromosomal loci with typical repetitive clusters and associated genes encoding a range of Cas proteins. Adaptation of CRISPR arrays occurs when virus-derived and plasmid-derived sequences are integrated as new CRISPR spacers. Cas proteins use CRISPR-derived RNA guides to specifically recognize and cleave nucleic acids of invading mobile genetic elements. Apart from this role as an adaptive immune system, some CRISPR-associated nucleases are hijacked by mobile genetic elements: viruses use them to attack their prokaryotic hosts, and transposons have adopted CRISPR systems for guided transposition. In addition, some CRISPR-Cas systems control the expression of genes involved in bacterial physiology and virulence. Moreover, pathogenic bacteria may use their Cas nuclease activity indirectly to evade the human immune system or directly to invade the nucleus and damage the chromosomal DNA of infected human cells. Thus, the evolutionary arms race has led to the expansion of exciting variations in CRISPR mechanisms and functionalities. In this Review, we explore the latest insights into the diverse functions of CRISPR-Cas systems beyond adaptive immunity and discuss the implications for the development of CRISPR-based applications.
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15
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Yang L, Zhang Y, Yin P, Feng Y. Structural insights into the inactivation of the type I-F CRISPR-Cas system by anti-CRISPR proteins. RNA Biol 2021; 18:562-573. [PMID: 34606423 DOI: 10.1080/15476286.2021.1985347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Phage infection is one of the major threats to prokaryotic survival, and prokaryotes in turn have evolved multiple protection approaches to fight against this challenge. Various delicate mechanisms have been discovered from this eternal arms race, among which the CRISPR-Cas systems are the prokaryotic adaptive immune systems and phages evolve diverse anti-CRISPR (Acr) proteins to evade this immunity. Until now, about 90 families of Acr proteins have been identified, out of which 24 families were verified to fight against subtype I-F CRISPR-Cas systems. Here, we review the structural and biochemical mechanisms of the characterized type I-F Acr proteins, classify their inhibition mechanisms into two major groups and provide insights for future studies of other Acr proteins. Understanding Acr proteins in this context will lead to a variety of practical applications in genome editing and also provide exciting insights into the molecular arms race between prokaryotes and phages.
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Affiliation(s)
- Lingguang Yang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China.,Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, Department of Chemistry and Bioengineering, Yichun University, Yichun, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
| | - Peipei Yin
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China.,Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, Department of Chemistry and Bioengineering, Yichun University, Yichun, China
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China
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16
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Liu X, Zhang L, Xiu Y, Gao T, Huang L, Xie Y, Yang L, Wang W, Wang P, Zhang Y, Yang M, Feng Y. Insights into the dual functions of AcrIF14 during the inhibition of type I-F CRISPR-Cas surveillance complex. Nucleic Acids Res 2021; 49:10178-10191. [PMID: 34432044 PMCID: PMC8464039 DOI: 10.1093/nar/gkab738] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/20/2021] [Accepted: 08/17/2021] [Indexed: 11/21/2022] Open
Abstract
CRISPR–Cas systems are bacterial adaptive immune systems, and phages counteract these systems using many approaches such as producing anti-CRISPR (Acr) proteins. Here, we report the structures of both AcrIF14 and its complex with the crRNA-guided surveillance (Csy) complex. Our study demonstrates that apart from interacting with the Csy complex to block the hybridization of target DNA to the crRNA, AcrIF14 also endows the Csy complex with the ability to interact with non-sequence-specific dsDNA as AcrIF9 does. Further structural studies of the Csy–AcrIF14–dsDNA complex and biochemical studies uncover that the PAM recognition loop of the Cas8f subunit of the Csy complex and electropositive patches within the N-terminal domain of AcrIF14 are essential for the non-sequence-specific dsDNA binding to the Csy–AcrIF14 complex, which is different from the mechanism of AcrIF9. Our findings highlight the prevalence of Acr-induced non-specific DNA binding and shed light on future studies into the mechanisms of such Acr proteins.
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Affiliation(s)
- Xi Liu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Laixing Zhang
- Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Tsinghua-Peking Center for Life Sciences, 100084 Beijing, China
| | - Yu Xiu
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Teng Gao
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Ling Huang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Yongchao Xie
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Lingguang Yang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Wenhe Wang
- Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Tsinghua-Peking Center for Life Sciences, 100084 Beijing, China
| | - Peiyi Wang
- Cryo-EM Centre, Department of Biology, Southern University of Science and Technology, 515055 Shenzhen, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Tsinghua-Peking Center for Life Sciences, 100084 Beijing, China
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029 Beijing, China
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17
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Jia N, Patel DJ. Structure-based functional mechanisms and biotechnology applications of anti-CRISPR proteins. Nat Rev Mol Cell Biol 2021; 22:563-579. [PMID: 34089013 DOI: 10.1038/s41580-021-00371-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2021] [Indexed: 02/03/2023]
Abstract
CRISPR loci and Cas proteins provide adaptive immunity in prokaryotes against invading bacteriophages and plasmids. In response, bacteriophages have evolved a broad spectrum of anti-CRISPR proteins (anti-CRISPRs) to counteract and overcome this immunity pathway. Numerous anti-CRISPRs have been identified to date, which suppress single-subunit Cas effectors (in CRISPR class 2, type II, V and VI systems) and multisubunit Cascade effectors (in CRISPR class 1, type I and III systems). Crystallography and cryo-electron microscopy structural studies of anti-CRISPRs bound to effector complexes, complemented by functional experiments in vitro and in vivo, have identified four major CRISPR-Cas suppression mechanisms: inhibition of CRISPR-Cas complex assembly, blocking of target binding, prevention of target cleavage, and degradation of cyclic oligonucleotide signalling molecules. In this Review, we discuss novel mechanistic insights into anti-CRISPR function that have emerged from X-ray crystallography and cryo-electron microscopy studies, and how these structures in combination with function studies provide valuable tools for the ever-growing CRISPR-Cas biotechnology toolbox, to be used for precise and robust genome editing and other applications.
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Affiliation(s)
- Ning Jia
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA. .,Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China.
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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18
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Lu WT, Trost CN, Müller-Esparza H, Randau L, Davidson AR. Anti-CRISPR AcrIF9 functions by inducing the CRISPR-Cas complex to bind DNA non-specifically. Nucleic Acids Res 2021; 49:3381-3393. [PMID: 33660777 PMCID: PMC8034650 DOI: 10.1093/nar/gkab092] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 01/28/2021] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
Phages and other mobile genetic elements express anti-CRISPR proteins (Acrs) to protect their genomes from destruction by CRISPR–Cas systems. Acrs usually block the ability of CRISPR–Cas systems to bind or cleave their nucleic acid substrates. Here, we investigate an unusual Acr, AcrIF9, that induces a gain-of-function to a type I-F CRISPR–Cas (Csy) complex, causing it to bind strongly to DNA that lacks both a PAM sequence and sequence complementarity. We show that specific and non-specific dsDNA compete for the same site on the Csy:AcrIF9 complex with rapid exchange, but specific ssDNA appears to still bind through complementarity to the CRISPR RNA. Induction of non-specific DNA-binding is a shared property of diverse AcrIF9 homologues. Substitution of a conserved positively charged surface on AcrIF9 abrogated non-specific dsDNA-binding of the Csy:AcrIF9 complex, but specific dsDNA binding was maintained. AcrIF9 mutants with impaired non-specific dsDNA binding activity in vitro displayed a reduced ability to inhibit CRISPR–Cas activity in vivo. We conclude that misdirecting the CRISPR–Cas complex to bind non-specific DNA is a key component of the inhibitory mechanism of AcrIF9. This inhibitory mechanism is distinct from a previously characterized anti-CRISPR, AcrIF1, that sterically blocks DNA-binding, even though AcrIF1and AcrIF9 bind to the same site on the Csy complex.
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Affiliation(s)
- Wang-Ting Lu
- Department of Biochemistry, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
| | - Chantel N Trost
- Department of Molecular Genetics, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
| | - Hanna Müller-Esparza
- Faculty of Biology, University of Marburg, Karl-von-Frisch-Straße 1, 35043 Marburg, Germany
| | - Lennart Randau
- Faculty of Biology, University of Marburg, Karl-von-Frisch-Straße 1, 35043 Marburg, Germany.,Loewe Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Alan R Davidson
- Department of Biochemistry, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada.,Department of Molecular Genetics, University of Toronto, 661 University Ave, Toronto, ON, M5G 1M1, Canada
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19
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Gabel C, Li Z, Zhang H, Chang L. Structural basis for inhibition of the type I-F CRISPR-Cas surveillance complex by AcrIF4, AcrIF7 and AcrIF14. Nucleic Acids Res 2021; 49:584-594. [PMID: 33332569 PMCID: PMC7797054 DOI: 10.1093/nar/gkaa1199] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/22/2020] [Accepted: 12/14/2020] [Indexed: 12/21/2022] Open
Abstract
CRISPR-Cas systems are adaptive immune systems in bacteria and archaea to defend against mobile genetic elements (MGEs) and have been repurposed as genome editing tools. Anti-CRISPR (Acr) proteins are produced by MGEs to counteract CRISPR-Cas systems and can be used to regulate genome editing by CRISPR techniques. Here, we report the cryo-EM structures of three type I-F Acr proteins, AcrIF4, AcrIF7 and AcrIF14, bound to the type I-F CRISPR-Cas surveillance complex (the Csy complex) from Pseudomonas aeruginosa. AcrIF4 binds to an unprecedented site on the C-terminal helical bundle of Cas8f subunit, precluding conformational changes required for activation of the Csy complex. AcrIF7 mimics the PAM duplex of target DNA and is bound to the N-terminal DNA vise of Cas8f. Two copies of AcrIF14 bind to the thumb domains of Cas7.4f and Cas7.6f, preventing hybridization between target DNA and the crRNA. Our results reveal structural detail of three AcrIF proteins, each binding to a different site on the Csy complex for inhibiting degradation of MGEs.
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Affiliation(s)
- Clinton Gabel
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
| | - Zhuang Li
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
| | - Heng Zhang
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
| | - Leifu Chang
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.,Purdue University Center for Cancer Research, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
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20
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Mejdani M, Pawluk A, Maxwell KL, Davidson AR. Anti-CRISPR AcrIE2 Binds the Type I-E CRISPR-Cas Complex But Does Not Block DNA Binding. J Mol Biol 2020; 433:166759. [PMID: 33338493 DOI: 10.1016/j.jmb.2020.166759] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/02/2020] [Accepted: 12/09/2020] [Indexed: 02/06/2023]
Abstract
Anti-CRISPRs are protein inhibitors of CRISPR-Cas systems. They are produced by phages and other mobile genetic elements to evade CRISPR-Cas-mediated destruction. Anti-CRISPRs are remarkably diverse in sequence, structure, and functional mechanism; thus, structural and mechanistic investigations of anti-CRISPRs continue to yield exciting new insights. In this study, we used nuclear magnetic resonance (NMR) spectroscopy to determine the solution structure of AcrIE2, an anti-CRISPR that inhibits the type I-E CRISPR-Cas system of Pseudomonas aeruginosa. Guided by the structure, we used site-directed mutagenesis to identify key residues that are required for AcrIE2 function. Using affinity purification experiments, we found that AcrIE2 binds the type I-E CRISPR-Cas complex (Cascade). In vivo transcriptional assays, in which Cascade was targeted to promoter regions, demonstrated that Cascade still binds to DNA in the presence of AcrIE2. This is the first instance of a type I anti-CRISPR that binds to a CRISPR-Cas complex but does not prevent DNA-binding. Another unusual property of AcrIE2 is that the effect of Cascade:AcrIE2 complex binding to promoter regions varied depending on the position of the binding site. Most surprisingly, Cascade:AcrIE2 binding led to transcriptional activation in some cases rather than repression, which did not occur when Cascade alone bound to the same sites. We conclude that AcrIE2 operates through a distinct mechanism compared to other type I anti-CRISPRs. While AcrIE2 does not prevent Cascade from binding DNA, it likely blocks subsequent recruitment of the Cas3 nuclease to Cascade thereby preventing DNA cleavage.
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Affiliation(s)
- Marios Mejdani
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - April Pawluk
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Karen L Maxwell
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
| | - Alan R Davidson
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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21
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Liu TY, Doudna JA. Chemistry of Class 1 CRISPR-Cas effectors: Binding, editing, and regulation. J Biol Chem 2020; 295:14473-14487. [PMID: 32817336 PMCID: PMC7573268 DOI: 10.1074/jbc.rev120.007034] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 08/13/2020] [Indexed: 12/19/2022] Open
Abstract
Among the multiple antiviral defense mechanisms found in prokaryotes, CRISPR-Cas systems stand out as the only known RNA-programmed pathways for detecting and destroying bacteriophages and plasmids. Class 1 CRISPR-Cas systems, the most widespread and diverse of these adaptive immune systems, use an RNA-guided multiprotein complex to find foreign nucleic acids and trigger their destruction. In this review, we describe how these multisubunit complexes target and cleave DNA and RNA and how regulatory molecules control their activities. We also highlight similarities to and differences from Class 2 CRISPR-Cas systems, which use a single-protein effector, as well as other types of bacterial and eukaryotic immune systems. We summarize current applications of the Class 1 CRISPR-Cas systems for DNA/RNA modification, control of gene expression, and nucleic acid detection.
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Affiliation(s)
- Tina Y Liu
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
- Department of Chemistry, University of California, Berkeley, California, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California, USA
- Innovative Genomics Institute, University of California, Berkeley, California, USA
- Howard Hughes Medical Institute, University of California, Berkeley, California, USA
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Gladstone Institutes, University of California, San Francisco, California, USA
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