1
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Guo J, Gong L, Yu H, Li M, An Q, Liu Z, Fan S, Yang C, Zhao D, Han J, Xiang H. Engineered minimal type I CRISPR-Cas system for transcriptional activation and base editing in human cells. Nat Commun 2024; 15:7277. [PMID: 39179566 DOI: 10.1038/s41467-024-51695-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 08/15/2024] [Indexed: 08/26/2024] Open
Abstract
Type I CRISPR-Cas systems are widespread and have exhibited high versatility and efficiency in genome editing and gene regulation in prokaryotes. However, due to the multi-subunit composition and large size, their application in eukaryotes has not been thoroughly investigated. Here, we demonstrate that the type I-F2 Cascade, the most compact among type I systems, with a total gene size smaller than that of SpCas9, can be developed for transcriptional activation in human cells. The efficiency of the engineered I-F2 tool can match or surpass that of dCas9. Additionally, we create a base editor using the I-F2 Cascade, which induces a considerably wide editing window (~30 nt) with a bimodal distribution. It can expand targetable sites, which is useful for disrupting functional sequences and genetic screening. This research underscores the application of compact type I systems in eukaryotes, particularly in the development of a base editor with a wide editing window.
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Affiliation(s)
- Jing Guo
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
| | - Haiying Yu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Qiaohui An
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Zhenquan Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Shuru Fan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Changjialian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Dahe Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China.
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
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2
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Hu K, Chou CW, Wilke CO, Finkelstein IJ. Distinct horizontal transfer mechanisms for type I and type V CRISPR-associated transposons. Nat Commun 2024; 15:6653. [PMID: 39103341 DOI: 10.1038/s41467-024-50816-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 07/22/2024] [Indexed: 08/07/2024] Open
Abstract
CASTs use both CRISPR-associated proteins and Tn7-family transposons for RNA-guided vertical and horizontal transmission. CASTs encode minimal CRISPR arrays but can't acquire new spacers. Here, we report that CASTs can co-opt defense-associated CRISPR arrays for horizontal transmission. A bioinformatic analysis shows that CASTs co-occur with defense-associated CRISPR systems, with the highest prevalence for type I-B and type V CAST sub-types. Using an E. coli quantitative transposition assay and in vitro reconstitution, we show that CASTs can use CRISPR RNAs from these defense systems. A high-resolution structure of the type I-F CAST-Cascade in complex with a type III-B CRISPR RNA reveals that Cas6 recognizes direct repeats via sequence-independent π - π interactions. In addition to using heterologous CRISPR arrays, type V CASTs can also transpose via an unguided mechanism, even when the S15 co-factor is over-expressed. Over-expressing S15 and the trans-activating CRISPR RNA or a single guide RNA reduces, but does not abrogate, off-target integration for type V CASTs. Our findings suggest that some CASTs may exploit defense-associated CRISPR arrays and that this fact must be considered when porting CASTs to heterologous bacterial hosts. More broadly, this work will guide further efforts to engineer the activity and specificity of CASTs for gene editing applications.
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Affiliation(s)
- Kuang Hu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Chia-Wei Chou
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Claus O Wilke
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, 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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3
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Yang Z, Li Z, Li B, Bu R, Tan GY, Wang Z, Yan H, Xin Z, Zhang G, Li M, Xiang H, Zhang L, Wang W. A thermostable type I-B CRISPR-Cas system for orthogonal and multiplexed genetic engineering. Nat Commun 2023; 14:6193. [PMID: 37794017 PMCID: PMC10551041 DOI: 10.1038/s41467-023-41973-5] [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: 04/19/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023] Open
Abstract
Thermophilic cell factories have remarkably broad potential for industrial applications, but are limited by a lack of genetic manipulation tools and recalcitrance to transformation. Here, we identify a thermophilic type I-B CRISPR-Cas system from Parageobacillus thermoglucosidasius and find it displays highly efficient transcriptional repression or DNA cleavage activity that can be switched by adjusting crRNA length to less than or greater than 26 bp, respectively, without ablating Cas3 nuclease. We then develop an orthogonal tool for genome editing and transcriptional repression using this type I-B system in both thermophile and mesophile hosts. Empowered by this tool, we design a strategy to screen the genome-scale targets involved in transformation efficiency and established dynamically controlled supercompetent P. thermoglucosidasius cells with high efficiency ( ~ 108 CFU/μg DNA) by temporal multiplexed repression. We also demonstrate the construction of thermophilic riboflavin cell factory with hitherto highest titers in high temperature fermentation by genome-scale identification and combinatorial manipulation of multiple targets. This work enables diverse high-efficiency genetic manipulation in P. thermoglucosidasius and facilitates the engineering of thermophilic cell factories.
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Affiliation(s)
- Zhiheng Yang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Zilong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Bixiao Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Ruihong Bu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- School of Medicine and Pharmacy, Ocean University of China, 266003, Qingdao, China
| | - Gao-Yi Tan
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Zhengduo Wang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China
| | - Hao Yan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Zhenguo Xin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
| | - Guojian Zhang
- School of Medicine and Pharmacy, Ocean University of China, 266003, Qingdao, China
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Lixin Zhang
- State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), 200237, Shanghai, China.
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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4
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Hu K, Chia-Wei C, Wilke CO, Finkelstein IJ. Distinct horizontal transfer mechanisms for type I and type V CRISPR-associated transposons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.03.531003. [PMID: 37502928 PMCID: PMC10369902 DOI: 10.1101/2023.03.03.531003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
CRISPR-associated transposons (CASTs) co-opt CRISPR-Cas proteins and Tn7-family transposons for RNA-guided vertical and horizontal transmission. CASTs encode minimal CRISPR arrays but can't acquire new spacers. Here, we show that CASTs instead co-opt defense-associated CRISPR arrays for horizontal transmission. A bioinformatic analysis shows that all CAST sub-types co-occur with defense-associated CRISPR-Cas systems. Using an E. coli quantitative transposition assay, we show that CASTs use CRISPR RNAs (crRNAs) from these defense systems for horizontal gene transfer. A high-resolution structure of the type I-F CAST-Cascade in complex with a type III-B crRNA reveals that Cas6 recognizes direct repeats via sequence-independent π - π interactions. In addition to using heterologous CRISPR arrays, type V CASTs can also transpose via a crRNA-independent unguided mechanism, even when the S15 co-factor is over-expressed. Over-expressing S15 and the trans-activating CRISPR RNA (tracrRNA) or a single guide RNA (sgRNA) reduces, but does not abrogate, off-target integration for type V CASTs. Exploiting new spacers in defense-associated CRISPR arrays explains how CASTs horizontally transfer to new hosts. More broadly, this work will guide further efforts to engineer the activity and specificity of CASTs for gene editing applications.
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Affiliation(s)
- Kuang Hu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Chou Chia-Wei
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Claus O. Wilke
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Ilya J. Finkelstein
- Department of Molecular Biosciences, 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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5
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Hussain MS, Anand V, Kumar M. Functional PAM sequence for DNA interference by CRISPR-Cas I-B system of Leptospira interrogans and the role of LinCas11b encoded within lincas8b. Int J Biol Macromol 2023; 237:124086. [PMID: 36940764 DOI: 10.1016/j.ijbiomac.2023.124086] [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: 12/14/2022] [Revised: 02/18/2023] [Accepted: 03/15/2023] [Indexed: 03/23/2023]
Abstract
Pathogenic species of Leptospira are recalcitrant for genetic manipulation using conventional tools, and therefore there is a need to explore techniques of higher efficiency. Application of endogenous CRISPR-Cas tool is emerging and efficient; nevertheless, it is limited by a poor understanding of interference machinery in the bacterial genome and its associated protospacer adjacent motif (PAM). In this study, interference machinery of CRISPR-Cas subtype I-B (Lin_I-B) from L. interrogans was experimentally validated in E. coli using the various identified PAM (TGA, ATG, ATA). The overexpression of the Lin_I-B interference machinery in E. coli demonstrated that LinCas5, LinCas6, LinCas7, and LinCas8b can self-assemble on cognate CRISPR RNA to form an interference complex (LinCascade). Moreover, a robust interference of target plasmids containing a protospacer with a PAM suggested a functional LinCascade. We also recognized a small open reading frame within lincas8b that independently co-translates LinCas11b. A mutant variant of LinCascade-Cas11b that lacks LinCas11b co-expression erred to mount target plasmid interference. At the same time, LinCas11b complementation in LinCascade-Cas11b rescued target plasmid interference. Thus, the present study establishes Leptospira subtype I-B interference machinery to be functional and, soon, may pave the way for scientists to harness it as a programmable endogenous genetic manipulation tool.
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Affiliation(s)
- Md Saddam Hussain
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Vineet Anand
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Manish Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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6
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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: 2] [Impact Index Per Article: 1.0] [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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7
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Hussain MS, Kumar M. Assembly of Cas7 subunits of Leptospira on the mature crRNA of CRISPR-Cas I-B is modulated by divalent ions. Gene X 2022; 818:146244. [PMID: 35074418 DOI: 10.1016/j.gene.2022.146244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/10/2022] [Accepted: 01/18/2022] [Indexed: 01/02/2023] Open
Abstract
The spirochete Leptospira interrogans serovar Copenhageni harbors the genetic elements of the CRISPR-Cas type I-B system in its genome. CRISPR-Cas is a CRISPR RNA (crRNA) mediated adaptive immune system in most prokaryotes against mobile genetic elements (MGEs). To eliminate the intruding MGEs, CRISPR-Cas type I systems utilize a Cascade (CRISPR-associated complex for antiviral defense) complex composed of Cas5, Cas6, Cas7, and Cas8 bound with a crRNA. The Cas7 is essentially known to constitute the major component of the Cascade complex. The present study reports the biochemical characterization of the Cas7 (LinCas7) from the CRISPR-Cas type I-B system of L. interrogans serovar Copenhageni. The pure recombinant LinCas7 (rLinCas7) exists as a monomer in the solution by size exclusion chromatography. The rLinCas7 demonstrates an endoDNase activity dependent upon divalent Mg2+ ions, monovalent ions, pH, temperature, and substrate size. Analysis of ribonucleoprotein composite (rLinCas7-crRNA) by electron microscopy and native-PAGE demonstrated that rLinCas7 could oligomerize on the mature CRISPR RNA (crRNA) framework in the presence of Mg2+ ions. The ribonucleoprotein composite attains a helical shape similar to the backbone of the Cascade complex. However, in the absence of Mg2+ ions, rLinCas7 acts as an RNase. The fluorescence spectroscopy disclosed a weak interaction (Kd = 26.81 mM) between rLinCas7 and Mg2+ ions, leading to an overall conformational change in rLinCas7 that modulates the rLinCas7's activity on DNA and RNA substrates. The nuclease activity of LinCas7 characterized in this study aids to the functional divergences among proteins of the Cas7 family from different CRISPR-Cas systems in various organisms.
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Affiliation(s)
- Md Saddam Hussain
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 7810 39, Assam, India
| | - Manish Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 7810 39, Assam, India.
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8
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Du K, Gong L, Li M, Yu H, Xiang H. Reprogramming the endogenous type I CRISPR-Cas system for simultaneous gene regulation and editing in Haloarcula hispanica. MLIFE 2022; 1:40-50. [PMID: 38818324 PMCID: PMC10989794 DOI: 10.1002/mlf2.12010] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 06/01/2024]
Abstract
The type I system is the most widely distributed CRISPR-Cas system identified so far. Recently, we have revealed the natural reprogramming of the type I CRISPR effector for gene regulation with a crRNA-resembling RNA in halophilic archaea. Here, we conducted a comprehensive study of the impact of redesigned crRNAs with different spacer lengths on gene regulation with the native type I-B CRISPR system in Haloarcula hispanica. When the spacer targeting the chromosomal gene was shortened from 36 to 28 bp, transformation efficiencies of the spacer-encoding plasmids were improved by over three orders of magnitude, indicating a significant loss of interference. However, by conducting whole-genome sequencing and measuring the growth curves of the hosts, we still detected DNA cleavage and its influence on cell growth. Intriguingly, when the spacer was shortened to 24 bp, the transcription of the target gene was downregulated to 10.80%, while both interference and primed adaptation disappeared. By modifying the lengths of the spacers, the expression of the target gene could be suppressed to varying degrees. Significantly, by designing crRNAs with different spacer lengths and targeting different genes, we achieved simultaneous gene editing (cdc6E) and gene regulation (crtB) for the first time with the endogenous type I CRISPR-Cas system.
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Affiliation(s)
- Kaixin Du
- State Key Laboratory of Microbial Resources, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Haiying Yu
- State Key Laboratory of Microbial Resources, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of MicrobiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
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9
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Rybarski JR, Hu K, Hill AM, Wilke CO, Finkelstein IJ. Metagenomic discovery of CRISPR-associated transposons. Proc Natl Acad Sci U S A 2021; 118:e2112279118. [PMID: 34845024 PMCID: PMC8670466 DOI: 10.1073/pnas.2112279118] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022] Open
Abstract
CRISPR-associated Tn7 transposons (CASTs) co-opt cas genes for RNA-guided transposition. CASTs are exceedingly rare in genomic databases; recent surveys have reported Tn7-like transposons that co-opt Type I-F, I-B, and V-K CRISPR effectors. Here, we expand the diversity of reported CAST systems via a bioinformatic search of metagenomic databases. We discover architectures for all known CASTs, including arrangements of the Cascade effectors, target homing modalities, and minimal V-K systems. We also describe families of CASTs that have co-opted the Type I-C and Type IV CRISPR-Cas systems. Our search for non-Tn7 CASTs identifies putative candidates that include a nuclease dead Cas12. These systems shed light on how CRISPR systems have coevolved with transposases and expand the programmable gene-editing toolkit.
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Affiliation(s)
- James R Rybarski
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
| | - Kuang Hu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Alexis M Hill
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Claus O Wilke
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712;
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712;
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712
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10
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Nobrega FL, Walinga H, Dutilh BE, Brouns SJJ. Prophages are associated with extensive CRISPR-Cas auto-immunity. Nucleic Acids Res 2020; 48:12074-12084. [PMID: 33219687 PMCID: PMC7708048 DOI: 10.1093/nar/gkaa1071] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas systems require discriminating self from non-self DNA during adaptation and interference. Yet, multiple cases have been reported of bacteria containing self-targeting spacers (STS), i.e. CRISPR spacers targeting protospacers on the same genome. STS has been suggested to reflect potential auto-immunity as an unwanted side effect of CRISPR-Cas defense, or a regulatory mechanism for gene expression. Here we investigated the incidence, distribution, and evasion of STS in over 100 000 bacterial genomes. We found STS in all CRISPR-Cas types and in one fifth of all CRISPR-carrying bacteria. Notably, up to 40% of I-B and I-F CRISPR-Cas systems contained STS. We observed that STS-containing genomes almost always carry a prophage and that STS map to prophage regions in more than half of the cases. Despite carrying STS, genetic deterioration of CRISPR-Cas systems appears to be rare, suggesting a level of escape from the potentially deleterious effects of STS by other mechanisms such as anti-CRISPR proteins and CRISPR target mutations. We propose a scenario where it is common to acquire an STS against a prophage, and this may trigger more extensive STS buildup by primed spacer acquisition in type I systems, without detrimental autoimmunity effects as mechanisms of auto-immunity evasion create tolerance to STS-targeted prophages.
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Affiliation(s)
- Franklin L Nobrega
- Department of Bionanoscience, Delft University of Technology, Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands
| | - Hielke Walinga
- Department of Bionanoscience, Delft University of Technology, Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands
| | - Bas E Dutilh
- Theoretical Biology and Bioinformatics, Science4Life, Utrecht University, Utrecht, Netherlands
| | - Stan J J Brouns
- Department of Bionanoscience, Delft University of Technology, Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands
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11
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Petassi MT, Hsieh SC, Peters JE. Guide RNA Categorization Enables Target Site Choice in Tn7-CRISPR-Cas Transposons. Cell 2020; 183:1757-1771.e18. [PMID: 33271061 PMCID: PMC7770071 DOI: 10.1016/j.cell.2020.11.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/10/2020] [Accepted: 11/03/2020] [Indexed: 01/08/2023]
Abstract
CRISPR-Cas defense systems have been coopted multiple times in nature for guide RNA-directed transposition by Tn7-like elements. Prototypic Tn7 uses dedicated proteins for two targeting pathways: one targeting a neutral and conserved attachment site in the chromosome and a second directing transposition into mobile plasmids facilitating cell-to-cell transfer. We show that Tn7-CRISPR-Cas elements evolved a system of guide RNA categorization to accomplish the same two-pathway lifestyle. Multiple mechanisms allow functionally distinct guide RNAs for transposition: a conventional system capable of acquiring guide RNAs to new plasmid and phage targets and a second providing long-term memory for access to chromosomal sites upon entry into a new host. Guide RNAs are privatized to be recognized only by the transposon-adapted system via sequence specialization, mismatch tolerance, and selective regulation to avoid toxic self-targeting by endogenous CRISPR-Cas defense systems. This information reveals promising avenues to engineer guide RNAs for enhanced CRISPR-Cas functionality for genome modification.
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Affiliation(s)
- Michael T Petassi
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Shan-Chi Hsieh
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
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12
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Tuminauskaite D, Norkunaite D, Fiodorovaite M, Tumas S, Songailiene I, Tamulaitiene G, Sinkunas T. DNA interference is controlled by R-loop length in a type I-F1 CRISPR-Cas system. BMC Biol 2020; 18:65. [PMID: 32539804 PMCID: PMC7296934 DOI: 10.1186/s12915-020-00799-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 05/20/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND CRISPR-Cas systems, which provide adaptive immunity against foreign nucleic acids in prokaryotes, can serve as useful molecular tools for multiple applications in genome engineering. Diverse CRISPR-Cas systems originating from distinct prokaryotes function through a common mechanism involving the assembly of small crRNA molecules and Cas proteins into a ribonucleoprotein (RNP) effector complex, and formation of an R-loop structure upon binding to the target DNA. Extensive research on the I-E subtype established the prototypical mechanism of DNA interference in type I systems, where the coordinated action of a ribonucleoprotein Cascade complex and Cas3 protein destroys foreign DNA. However, diverse protein composition between type I subtypes suggests differences in the mechanism of DNA interference that could be exploited for novel practical applications that call for further exploration of these systems. RESULTS Here we examined the mechanism of DNA interference provided by the type I-F1 system from Aggregatibacter actinomycetemcomitans D7S-1 (Aa). We show that functional Aa-Cascade complexes can be assembled not only with WT spacer of 32 nt but also with shorter or longer (14-176 nt) spacers. All complexes guided by the spacer bind to the target DNA sequence (protospacer) forming an R-loop when a C or CT protospacer adjacent motif (PAM) is present immediately upstream the protospacer (at -1 or -2,-1 position, respectively). The range of spacer and protospacer complementarity predetermine the length of the R-loop; however, only R-loops of WT length or longer trigger the nuclease/helicase Cas2/3, which initiates ATP-dependent unidirectional degradation at the PAM-distal end of the WT R-loop. Meanwhile, truncation of the WT R-loop at the PAM-distal end abolishes Cas2/3 cleavage. CONCLUSIONS We provide a comprehensive characterisation of the DNA interference mechanism in the type I-F1 CRISPR-Cas system, which is different from the type I-E in a few aspects. First, DNA cleavage initiation, which usually happens at the PAM-proximal end in type I-E, is shifted to the PAM-distal end of WT R-loop in the type I-F1. Second, the R-loop length controls on/off switch of DNA interference in the type I-F1, while cleavage initiation is less restricted in the type I-E. These results indicate that DNA interference in type I-F1 systems is governed through a checkpoint provided by the Cascade complex, which verifies the appropriate length for the R-loop.
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Affiliation(s)
- Donata Tuminauskaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania
| | - Danguole Norkunaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania
| | - Marija Fiodorovaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania
| | - Sarunas Tumas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania.,Pressent Address: Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Lyngby, Denmark
| | - Inga Songailiene
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania
| | - Giedre Tamulaitiene
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania
| | - Tomas Sinkunas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio av. 7, LT-10257, Vilnius, Lithuania.
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13
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Mekler V, Kuznedelov K, Severinov K. Quantification of the affinities of CRISPR-Cas9 nucleases for cognate protospacer adjacent motif (PAM) sequences. J Biol Chem 2020; 295:6509-6517. [PMID: 32241913 PMCID: PMC7212624 DOI: 10.1074/jbc.ra119.012239] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/31/2020] [Indexed: 11/06/2022] Open
Abstract
The CRISPR/Cas9 nucleases have been widely applied for genome editing in various organisms. Cas9 nucleases complexed with a guide RNA (Cas9-gRNA) find their targets by scanning and interrogating the genomic DNA for sequences complementary to the gRNA. Recognition of the DNA target sequence requires a short protospacer adjacent motif (PAM) located outside this sequence. Given that the efficiency of target location may depend on the strength of interactions that promote target recognition, here we sought to compare affinities of different Cas9 nucleases for their cognate PAM sequences. To this end, we measured affinities of Cas9 nucleases from Streptococcus pyogenes, Staphylococcus aureus, and Francisella novicida complexed with guide RNAs (gRNAs) (SpCas9-gRNA, SaCas9-gRNA, and FnCas9-gRNA, respectively) and of three engineered SpCas9-gRNA variants with altered PAM specificities for short, PAM-containing DNA probes. We used a "beacon" assay that measures the relative affinities of DNA probes by determining their ability to competitively affect the rate of Cas9-gRNA binding to fluorescently labeled target DNA derivatives called "Cas9 beacons." We observed significant differences in the affinities for cognate PAM sequences among the studied Cas9 enzymes. The relative affinities of SpCas9-gRNA and its engineered variants for canonical and suboptimal PAMs correlated with previous findings on the efficiency of these PAM sequences in genome editing. These findings suggest that high affinity of a Cas9 nuclease for its cognate PAM promotes higher genome-editing efficiency.
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Affiliation(s)
- Vladimir Mekler
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854
| | - Konstantin Kuznedelov
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854
| | - Konstantin Severinov
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, New Jersey 08854
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 119334, Russia
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14
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Detection of CRISPR adaptation. Biochem Soc Trans 2020; 48:257-269. [PMID: 32010936 PMCID: PMC7054753 DOI: 10.1042/bst20190662] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/26/2019] [Accepted: 01/03/2020] [Indexed: 12/12/2022]
Abstract
Prokaryotic adaptive immunity is built when short DNA fragments called spacers are acquired into CRISPR (clustered regularly interspaced short palindromic repeats) arrays. CRISPR adaptation is a multistep process which comprises selection, generation, and incorporation of prespacers into arrays. Once adapted, spacers provide immunity through the recognition of complementary nucleic acid sequences, channeling them for destruction. To prevent deleterious autoimmunity, CRISPR adaptation must therefore be a highly regulated and infrequent process, at least in the absence of genetic invaders. Over the years, ingenious methods to study CRISPR adaptation have been developed. In this paper, we discuss and compare methods that detect CRISPR adaptation and its intermediates in vivo and propose suppressing PCR as a simple modification of a popular assay to monitor spacer acquisition with increased sensitivity.
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15
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Type I-F CRISPR-Cas Distribution and Array Dynamics in Legionella pneumophila. G3-GENES GENOMES GENETICS 2020; 10:1039-1050. [PMID: 31937548 PMCID: PMC7056967 DOI: 10.1534/g3.119.400813] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In bacteria and archaea, several distinct types of CRISPR-Cas systems provide adaptive immunity through broadly similar mechanisms: short nucleic acid sequences derived from foreign DNA, known as spacers, engage in complementary base pairing with invasive genetic elements setting the stage for nucleases to degrade the target DNA. A hallmark of type I CRISPR-Cas systems is their ability to acquire spacers in response to both new and previously encountered invaders (naïve and primed acquisition, respectively). Our phylogenetic analyses of 43 L. pneumophila type I-F CRISPR-Cas systems and their resident genomes suggest that many of these systems have been horizontally acquired. These systems are frequently encoded on plasmids and can co-occur with nearly identical chromosomal loci. We show that two such co-occurring systems are highly protective and undergo efficient primed acquisition in the lab. Furthermore, we observe that targeting by one system’s array can prime spacer acquisition in the other. Lastly, we provide experimental and genomic evidence for a model in which primed acquisition can efficiently replenish a depleted type I CRISPR array following a mass spacer deletion event.
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16
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Wittig S, Songailiene I, Schmidt C. Formation and Stoichiometry of CRISPR-Cascade Complexes with Varying Spacer Lengths Revealed by Native Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:538-546. [PMID: 32008319 DOI: 10.1021/jasms.9b00011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The adaptive immune system of bacteria and archaea against viral DNA is based on clustered, regularly interspaced, short palindromic repeats (CRISPRs) which are encoded in the host genome and translated into CRISPR RNAs (crRNAs) containing single spacer sequences complementary to foreign DNA. crRNAs assemble with CRISPR-associated (Cas) proteins forming surveillance complexes that base-pair with viral DNA and mediate its degradation. As specificity of degradation is provided by the crRNA spacer sequence, genetic engineering of the CRISPR system has emerged as a popular molecular tool, for instance, in gene silencing and programmed DNA degradation. Elongating or shortening the crRNA spacer sequence are therefore promising ventures to modify specificity toward the target DNA. However, even though the stoichiometry of wild-type complexes is well established, it is unknown how variations in crRNA spacer length affect their stoichiometry. The CRISPR-associated antiviral defense surveillance complexes of Streptococcus thermophilus (StCascade complexes) contain crRNA and five protein subunits. Using native mass spectrometry, we studied the formation and stoichiometry of StCascade complexes assembled on a set of crRNAs with different spacer lengths. We assigned all relevant complexes and gained insights into the stoichiometry of the complexes as well as their preferred assembly. We found that stable complexes, which incorporate or lose a (Cas7)2(Cse2)1-module, assemble on crRNA varied in length by 12-nucleotide units, while varying crRNA length in six-nucleotide units results in heterogeneous mixtures of complexes. Combining our results from the various variants, we generated an assembly pathway revealing general features of I-E type Cascade complex formation.
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Affiliation(s)
- Sabine Wittig
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 3a, 06120 Halle, Germany
| | - Inga Songailiene
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, 7 Saulėtekio Avenue, 10257 Vilnius, Lithuania
| | - Carla Schmidt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 3a, 06120 Halle, Germany
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17
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Characterization and applications of Type I CRISPR-Cas systems. Biochem Soc Trans 2020; 48:15-23. [DOI: 10.1042/bst20190119] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/13/2019] [Accepted: 12/17/2019] [Indexed: 12/14/2022]
Abstract
CRISPR-Cas constitutes the adaptive immune system of bacteria and archaea. This RNA-mediated sequence-specific recognition and targeting machinery has been used broadly for diverse applications in a wide range of organisms across the tree of life. The compact class 2 systems, that hinge on a single Cas effector nuclease have been harnessed for genome editing, transcriptional regulation, detection, imaging and other applications, in different research areas. However, most of the CRISPR-Cas systems belong to class 1, and the molecular machinery of the most widespread and diverse Type I systems afford tremendous opportunities for a broad range of applications. These highly abundant systems rely on a multi-protein effector complex, the CRISPR associated complex for antiviral defense (Cascade), which drives DNA targeting and cleavage. The complexity of these systems has somewhat hindered their widespread usage, but the pool of thousands of diverse Type I CRISPR-Cas systems opens new avenues for CRISPR-based applications in bacteria, archaea and eukaryotes. Here, we describe the features and mechanism of action of Type I CRISPR-Cas systems, illustrate how endogenous systems can be reprogrammed to target the host genome and perform genome editing and transcriptional regulation by co-delivering a minimal CRISPR array together with a repair template. Moreover, we discuss how these systems can also be used in eukaryotes. This review provides a framework for expanding the CRISPR toolbox, and repurposing the most abundant CRISPR-Cas systems for a wide range of applications.
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18
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Gu DH, Ha SC, Kim JS. A CRISPR RNA Is Closely Related With the Size of the Cascade Nucleoprotein Complex. Front Microbiol 2019; 10:2458. [PMID: 31736904 PMCID: PMC6828817 DOI: 10.3389/fmicb.2019.02458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 10/14/2019] [Indexed: 12/26/2022] Open
Abstract
The currently known prokaryotic adaptive immune system against mobile genetic elements is based on clustered regularly interspaced short palindromic repeats (CRISPR). CRISPR-associated (Cas) proteins and the transcribed short CRISPR RNA (crRNA) molecule form a heterologous ribonucleoprotein complex that neutralizes invading foreign nucleic acids, wherein the crRNA molecule base-pairs with the exogenous genetic elements. In the ribonucleoprotein complexes of the type I CRISPR system, a helical backbone of six identical subunits is commonly found. However, it is not clear how this ribonucleoprotein complex is assembled and what is the determinant factor for its size. We elucidated the crystal structure of the Csy3 subunit of the type I-F ribonucleoprotein complex from Zymomonas mobilis (ZmCsy3), in which seven ZmCsy3 protomers in the asymmetric unit form a molecular helix that is part of a filamentous structure in the entire crystal system. This ZmCsy3 helical structure is remarkably similar to the crRNA-bound hexameric Csy3 backbone from Pseudomonas aeruginosa, with conserved interactions between neighboring subunits. The monomeric ZmCsy3 in solution is transformed into different oligomeric states depending on the added crRNAs. These results suggest that a crRNA and Csy3 subunit play a determinant role in the stepwise formation of the functional Cascade ribonucleoprotein complex and the recruitment of other subunits, and crRNA functions as a molecular ruler for determining the size of the Cascade silencing complex.
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Affiliation(s)
- Do-Heon Gu
- Department of Chemistry, Chonnam National University, Gwangju, South Korea
| | - Sung Chul Ha
- Pohang Accelerator Laboratory, Pohang, South Korea
| | - Jeong-Sun Kim
- Department of Chemistry, Chonnam National University, Gwangju, South Korea
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19
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Songailiene I, Rutkauskas M, Sinkunas T, Manakova E, Wittig S, Schmidt C, Siksnys V, Seidel R. Decision-Making in Cascade Complexes Harboring crRNAs of Altered Length. Cell Rep 2019; 28:3157-3166.e4. [PMID: 31533038 PMCID: PMC6859484 DOI: 10.1016/j.celrep.2019.08.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 06/21/2019] [Accepted: 08/09/2019] [Indexed: 12/24/2022] Open
Abstract
The multi-subunit type I CRISPR-Cas surveillance complex Cascade uses its crRNA to recognize dsDNA targets. Recognition involves DNA unwinding and base-pairing between the crRNA spacer region and a complementary DNA strand, resulting in formation of an R-loop structure. The modular Cascade architecture allows assembly of complexes containing crRNAs with altered spacer lengths that promise increased target specificity in emerging biotechnological applications. Here we produce type I-E Cascade complexes containing crRNAs with up to 57-nt-long spacers. We show that these complexes form R-loops corresponding to the designed target length, even for the longest spacers tested. Furthermore, the complexes can bind their targets with much higher affinity compared with the wild-type form. However, target recognition and the subsequent Cas3-mediated DNA cleavage do not require extended R-loops but already occur for wild-type-sized R-loops. These findings set important limits for specificity improvements of type I CRISPR-Cas systems.
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Affiliation(s)
- Inga Songailiene
- Institute of Biotechnology, Vilnius University, Vilnius 10257, Lithuania
| | - Marius Rutkauskas
- Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany
| | - Tomas Sinkunas
- Institute of Biotechnology, Vilnius University, Vilnius 10257, Lithuania
| | - Elena Manakova
- Institute of Biotechnology, Vilnius University, Vilnius 10257, Lithuania
| | - Sabine Wittig
- HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Halle 06120, Germany
| | - Carla Schmidt
- HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Halle 06120, Germany
| | - Virginijus Siksnys
- Institute of Biotechnology, Vilnius University, Vilnius 10257, Lithuania.
| | - Ralf Seidel
- Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany.
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20
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Krivoy A, Rutkauskas M, Kuznedelov K, Musharova O, Rouillon C, Severinov K, Seidel R. Primed CRISPR adaptation in Escherichia coli cells does not depend on conformational changes in the Cascade effector complex detected in Vitro. Nucleic Acids Res 2019; 46:4087-4098. [PMID: 29596641 PMCID: PMC5934681 DOI: 10.1093/nar/gky219] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 03/14/2018] [Indexed: 11/13/2022] Open
Abstract
In type I CRISPR-Cas systems, primed adaptation of new spacers into CRISPR arrays occurs when the effector Cascade-crRNA complex recognizes imperfectly matched targets that are not subject to efficient CRISPR interference. Thus, primed adaptation allows cells to acquire additional protection against mobile genetic elements that managed to escape interference. Biochemical and biophysical studies suggested that Cascade-crRNA complexes formed on fully matching targets (subject to efficient interference) and on partially mismatched targets that promote primed adaption are structurally different. Here, we probed Escherichia coli Cascade-crRNA complexes bound to matched and mismatched DNA targets using a magnetic tweezers assay. Significant differences in complex stabilities were observed consistent with the presence of at least two distinct conformations. Surprisingly, in vivo analysis demonstrated that all mismatched targets stimulated robust primed adaptation irrespective of conformational states observed in vitro. Our results suggest that primed adaptation is a direct consequence of a reduced interference efficiency and/or rate and is not a consequence of distinct effector complex conformations on target DNA.
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Affiliation(s)
- Andrey Krivoy
- Center for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, Moscow 143028, Russia.,Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany
| | - Marius Rutkauskas
- Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany
| | - Konstantin Kuznedelov
- Waksman Institute, Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Olga Musharova
- Center for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, Moscow 143028, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Christophe Rouillon
- Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany
| | - Konstantin Severinov
- Center for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, Moscow 143028, Russia.,Waksman Institute, Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Ralf Seidel
- Molecular Biophysics Group, Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig 04103, Germany
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21
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Gong L, Li M, Cheng F, Zhao D, Chen Y, Xiang H. Primed adaptation tolerates extensive structural and size variations of the CRISPR RNA guide in Haloarcula hispanica. Nucleic Acids Res 2019; 47:5880-5891. [PMID: 30957847 PMCID: PMC6582329 DOI: 10.1093/nar/gkz244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/22/2019] [Accepted: 03/27/2019] [Indexed: 12/13/2022] Open
Abstract
Recent studies on CRISPR adaptation revealed that priming is a major pathway of spacer acquisition, at least for the most prevalent type I systems. Priming is guided by a CRISPR RNA which fully/partially matches the invader DNA, but the plasticity of this RNA guide has not yet been characterized. In this study, we extensively modified the two conserved handles of a priming crRNA in Haloarcula hispanica, and altered the size of its central spacer part. Interestingly, priming is insusceptible to the full deletion of 3' handle, which seriously impaired crRNA stability and interference effects. With 3' handle deletion, further truncation of 5' handle revealed that its spacer-proximal 6 nucleotides could provide the least conserved sequence required for priming. Subsequent scanning mutation further identified critical nucleotides within 5' handle. Besides, priming was also shown to tolerate a wider size variation of the spacer part, compared to interference. These data collectively illustrate the high tolerance of priming to extensive structural/size variations of the crRNA guide, which highlights the structural flexibility of the crRNA-effector ribonucleoprotein complex. The observed high priming effectiveness suggests that primed adaptation promotes clearance of the fast-replicating and ever-evolving viral DNA, by rapidly and persistently multiplexing the interference pathway.
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Affiliation(s)
- Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Feiyue Cheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dahe Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yihua Chen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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22
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Jain I, Minakhin L, Mekler V, Sitnik V, Rubanova N, Severinov K, Semenova E. Defining the seed sequence of the Cas12b CRISPR-Cas effector complex. RNA Biol 2019; 16:413-422. [PMID: 30022698 PMCID: PMC6546406 DOI: 10.1080/15476286.2018.1495492] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 06/12/2018] [Indexed: 12/14/2022] Open
Abstract
Target binding by CRISPR-Cas ribonucleoprotein effectors is initiated by the recognition of double-stranded PAM motifs by the Cas protein moiety followed by destabilization, localized melting, and interrogation of the target by the guide part of CRISPR RNA moiety. The latter process depends on seed sequences, parts of the target that must be strictly complementary to CRISPR RNA guide. Mismatches between the target and CRISPR RNA guide outside the seed have minor effects on target binding, thus contributing to off-target activity of CRISPR-Cas effectors. Here, we define the seed sequence of the Type V Cas12b effector from Bacillus thermoamylovorans. While the Cas12b seed is just five bases long, in contrast to all other effectors characterized to date, the nucleotide base at the site of target cleavage makes a very strong contribution to target binding. The generality of this additional requirement was confirmed during analysis of target recognition by Cas12b effector from Alicyclobacillus acidoterrestris. Thus, while the short seed may contribute to Cas12b promiscuity, the additional specificity determinant at the site of cleavage may have a compensatory effect making Cas12b suitable for specialized genome editing applications.
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Affiliation(s)
- Ishita Jain
- Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology, Piscataway, NJ, USA
- Skolkovo Institute of Science and Technology, Center of Life Sciences, Skolkovo, Russia
| | - Leonid Minakhin
- Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology, Piscataway, NJ, USA
| | - Vladimir Mekler
- Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology, Piscataway, NJ, USA
| | - Vasily Sitnik
- Skolkovo Institute of Science and Technology, Center of Life Sciences, Skolkovo, Russia
| | - Natalia Rubanova
- Skolkovo Institute of Science and Technology, Center of Life Sciences, Skolkovo, Russia
| | - Konstantin Severinov
- Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology, Piscataway, NJ, USA
- Skolkovo Institute of Science and Technology, Center of Life Sciences, Skolkovo, Russia
| | - Ekaterina Semenova
- Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology, Piscataway, NJ, USA
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23
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Xue C, Sashital DG. Mechanisms of Type I-E and I-F CRISPR-Cas Systems in Enterobacteriaceae. EcoSal Plus 2019; 8:10.1128/ecosalplus.ESP-0008-2018. [PMID: 30724156 PMCID: PMC6368399 DOI: 10.1128/ecosalplus.esp-0008-2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Indexed: 12/17/2022]
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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Affiliation(s)
- Chaoyou Xue
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA
- Present address: Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY
| | - Dipali G Sashital
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA
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24
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Patterson A, Tokmina-Lukaszewska M, Bothner B. Probing Cascade complex composition and stability using native mass spectrometry techniques. Methods Enzymol 2018; 616:87-116. [PMID: 30691656 DOI: 10.1016/bs.mie.2018.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adaptive prokaryotic immune systems rely on clustered regularly interspaced short palindromic repeats and their associated genes to provide the components necessary to clear infection by foreign genetic elements. These immune systems are based on highly specific nucleases that bind DNA or RNA and, upon sequence recognition, degrade the bound nucleic acid. Because of their specificity, CRISPR-Cas systems are being co-opted to edit genes in eukaryotic cells. While the general function of these systems is well understood, an understanding of mechanistic details to facilitate engineering and application to this new arena remains a topic of intense study. Here, we present two methods that have been successfully used to study the structure and mechanism of the Type IE CRISPR system, Cascade, from Escherichia coli. We provide the protocol for a typical native mass spectrometry experiment which, because it allows for analysis of a protein complex without disruption of the noncovalent interactions within the complex, can be used to determine complex composition, architecture, and relative affinity between subunits. We, also, provide the protocol for intact protein hydrogen-deuterium exchange mass spectrometry, which provides insight into the overall conformational stability of the complex and changes in complex stability based on conditions such as substrate binding. Investigating the solution-phase structure, stability, and dynamics of these complexes improves the overall understanding of the mechanism facilitating engineered adjustments to function or utility.
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Affiliation(s)
- Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | | | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States.
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25
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Mekler V, Kuznedelov K, Minakhin L, Murugan K, Sashital DG, Severinov K. CRISPR-Cas molecular beacons as tool for studies of assembly of CRISPR-Cas effector complexes and their interactions with DNA. Methods Enzymol 2018; 616:337-363. [PMID: 30691650 PMCID: PMC6930961 DOI: 10.1016/bs.mie.2018.10.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CRISPR-Cas systems protect prokaryotic cells from invading phages and plasmids by recognizing and cleaving foreign nucleic acid sequences specified by CRISPR RNA spacer sequences. Several CRISPR-Cas systems have been widely used as tool for genetic engineering. In DNA-targeting CRISPR-Cas nucleoprotein effector complexes, the CRISPR RNA forms a hybrid with the complementary strand of foreign DNA, displacing the noncomplementary strand to form an R-loop. The DNA interrogation and R-loop formation involve several distinct steps the molecular details of which are not fully understood. This chapter describes a recently developed fluorometric Cas beacon assay that may be used for measuring of specific affinity of various CRISPR-Cas complexes for unlabeled target DNA and model DNA probes. The Cas beacon approach also can provide a sensitive method for monitoring the kinetics of assembly of CRISPR-Cas complexes.
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Affiliation(s)
- Vladimir Mekler
- Waksman Institute of Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ, United States.
| | - Konstantin Kuznedelov
- Waksman Institute of Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ, United States
| | - Leonid Minakhin
- Waksman Institute of Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ, United States
| | - Karthik Murugan
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Ames, IA, United States
| | - Dipali G Sashital
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Ames, IA, United States
| | - Konstantin Severinov
- Waksman Institute of Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ, United States; Center for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, Russia; Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia.
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26
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Tarasava K, Oh EJ, Eckert CA, Gill RT. CRISPR-Enabled Tools for Engineering Microbial Genomes and Phenotypes. Biotechnol J 2018; 13:e1700586. [DOI: 10.1002/biot.201700586] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 05/09/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Katia Tarasava
- Chemical and Biological Engineering, University of Colorado; Boulder CO USA
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
| | - Eun Joong Oh
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
| | - Carrie A. Eckert
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
- Biosciences Center, National Renewable Energy Laboratory; Golden CO USA
| | - Ryan T. Gill
- Chemical and Biological Engineering, University of Colorado; Boulder CO USA
- Renewable and Sustainable Energy Institute, University of Colorado; Boulder CO USA
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27
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Maier LK, Stachler AE, Brendel J, Stoll B, Fischer S, Haas KA, Schwarz TS, Alkhnbashi OS, Sharma K, Urlaub H, Backofen R, Gophna U, Marchfelder A. The nuts and bolts of the Haloferax CRISPR-Cas system I-B. RNA Biol 2018; 16:469-480. [PMID: 29649958 PMCID: PMC6546412 DOI: 10.1080/15476286.2018.1460994] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Invading genetic elements pose a constant threat to prokaryotic survival, requiring an effective defence. Eleven years ago, the arsenal of known defence mechanisms was expanded by the discovery of the CRISPR-Cas system. Although CRISPR-Cas is present in the majority of archaea, research often focuses on bacterial models. Here, we provide a perspective based on insights gained studying CRISPR-Cas system I-B of the archaeon Haloferax volcanii. The system relies on more than 50 different crRNAs, whose stability and maintenance critically depend on the proteins Cas5 and Cas7, which bind the crRNA and form the Cascade complex. The interference machinery requires a seed sequence and can interact with multiple PAM sequences. H. volcanii stands out as the first example of an organism that can tolerate autoimmunity via the CRISPR-Cas system while maintaining a constitutively active system. In addition, the H. volcanii system was successfully developed into a tool for gene regulation.
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Affiliation(s)
| | | | | | | | | | - Karina A Haas
- a Biology II, Ulm University , Ulm , Germany.,b Microbiology and Biotechnology, Ulm University , Ulm , Germany
| | | | - Omer S Alkhnbashi
- c Freiburg Bioinformatics Group, Department of Computer Science , University of Freiburg , Georges-Köhler-Allee 106, Freiburg , Germany
| | - Kundan Sharma
- e Max Planck Institute of Biophysical Chemistry , Am Faßberg 11, Göttingen , Germany.,f Ludwig Institute for Cancer Research, University of Oxford , Oxford , United Kingdom
| | - Henning Urlaub
- e Max Planck Institute of Biophysical Chemistry , Am Faßberg 11, Göttingen , Germany.,g Institute for Clinical Chemistry, University Medical Center Göttingen , Robert Koch Straße 10, Göttingen , Germany
| | - Rolf Backofen
- c Freiburg Bioinformatics Group, Department of Computer Science , University of Freiburg , Georges-Köhler-Allee 106, Freiburg , Germany.,d Centre for Biological Signalling Studies (BIOSS), Cluster of Excellence, University of Freiburg , Germany
| | - Uri Gophna
- h School of Molecular Cell Biology & Biotechnology, George S. Wise, Faculty of Life Sciences, Tel Aviv University , Tel Aviv , Israel
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28
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Abstract
The adaptation phase of CRISPR-Cas immunity depends on the precise integration of short segments of foreign DNA (spacers) into a specific genomic location within the CRISPR locus by the Cas1-Cas2 integration complex. Although off-target spacer integration outside of canonical CRISPR arrays has been described in vitro, no evidence of non-specific integration activity has been found in vivo. Here, we show that non-canonical off-target integrations can occur within bacterial chromosomes at locations that resemble the native CRISPR locus by characterizing hundreds of off-target integration locations within Escherichia coli. Considering whether such promiscuous Cas1-Cas2 activity could have an evolutionary role through the genesis of neo-CRISPR loci, we combed existing CRISPR databases and available genomes for evidence of off-target integration activity. This search uncovered several putative instances of naturally occurring off-target spacer integration events within the genomes of Yersinia pestis and Sulfolobus islandicus. These results are important in understanding alternative routes to CRISPR array genesis and evolution, as well as in the use of spacer acquisition in technological applications.
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29
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Spontaneous CRISPR loci generation in vivo by non-canonical spacer integration. Nat Microbiol 2018; 3:310-318. [PMID: 29379209 DOI: 10.1038/s41564-017-0097-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/11/2017] [Indexed: 01/09/2023]
Abstract
The adaptation phase of CRISPR-Cas immunity depends on the precise integration of short segments of foreign DNA (spacers) into a specific genomic location within the CRISPR locus by the Cas1-Cas2 integration complex. Although off-target spacer integration outside of canonical CRISPR arrays has been described in vitro, no evidence of non-specific integration activity has been found in vivo. Here, we show that non-canonical off-target integrations can occur within bacterial chromosomes at locations that resemble the native CRISPR locus by characterizing hundreds of off-target integration locations within Escherichia coli. Considering whether such promiscuous Cas1-Cas2 activity could have an evolutionary role through the genesis of neo-CRISPR loci, we combed existing CRISPR databases and available genomes for evidence of off-target integration activity. This search uncovered several putative instances of naturally occurring off-target spacer integration events within the genomes of Yersinia pestis and Sulfolobus islandicus. These results are important in understanding alternative routes to CRISPR array genesis and evolution, as well as in the use of spacer acquisition in technological applications.
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30
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Li M, Gong L, Zhao D, Zhou J, Xiang H. The spacer size of I-B CRISPR is modulated by the terminal sequence of the protospacer. Nucleic Acids Res 2017; 45:4642-4654. [PMID: 28379481 PMCID: PMC5416893 DOI: 10.1093/nar/gkx229] [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: 01/19/2017] [Accepted: 03/25/2017] [Indexed: 12/29/2022] Open
Abstract
Prokaryotes memorize invader information by incorporating alien DNA as spacers into CRISPR arrays. Although the spacer size has been suggested to be predefined by the architecture of the acquisition complex, there is usually an unexpected heterogeneity. Here, we explored the causes of this heterogeneity in Haloarcula hispanica I-B CRISPR. High-throughput sequencing following adaptation assays demonstrated significant size variation among 37 957 new spacers, which appeared to be sequence-dependent. Consistently, the third nucleotide at the spacer 3΄-end (PAM-distal end) showed an evident bias for cytosine and mutating this cytosine in the protospacer sequence could change the final spacer size. In addition, slippage of the 5΄-end (PAM-end), which contributed to most of the observed PAM (protospacer adjacent motif) inaccuracy, also tended to change the spacer size. We propose that both ends of the PAM-protospacer sequence should exhibit nucleotide selectivity (with different stringencies), which fine-tunes the structural ruler, to a certain extent, to specify the spacer size.
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Affiliation(s)
- Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dahe Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jian Zhou
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
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31
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Chowdhury S, Carter J, Rollins MF, Golden SM, Jackson RN, Hoffmann C, Nosaka L, Bondy-Denomy J, Maxwell KL, Davidson AR, Fischer ER, Lander GC, Wiedenheft B. Structure Reveals Mechanisms of Viral Suppressors that Intercept a CRISPR RNA-Guided Surveillance Complex. Cell 2017; 169:47-57.e11. [PMID: 28340349 DOI: 10.1016/j.cell.2017.03.012] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/23/2017] [Accepted: 03/06/2017] [Indexed: 12/22/2022]
Abstract
Genetic conflict between viruses and their hosts drives evolution and genetic innovation. Prokaryotes evolved CRISPR-mediated adaptive immune systems for protection from viral infection, and viruses have evolved diverse anti-CRISPR (Acr) proteins that subvert these immune systems. The adaptive immune system in Pseudomonas aeruginosa (type I-F) relies on a 350 kDa CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-acting nuclease for target degradation. Here, we report the cryo-electron microscopy (cryo-EM) structure of the Csy complex bound to two different Acr proteins, AcrF1 and AcrF2, at an average resolution of 3.4 Å. The structure explains the molecular mechanism for immune system suppression, and structure-guided mutations show that the Acr proteins bind to residues essential for crRNA-mediated detection of DNA. Collectively, these data provide a snapshot of an ongoing molecular arms race between viral suppressors and the immune system they target.
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Affiliation(s)
- Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Joshua Carter
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - MaryClare F Rollins
- 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
| | - Ryan N Jackson
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Connor Hoffmann
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Lyn'Al Nosaka
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Karen L Maxwell
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Alan R Davidson
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Elizabeth R Fischer
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, MT 59840, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.
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32
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Koonin EV, Makarova KS, Zhang F. Diversity, classification and evolution of CRISPR-Cas systems. Curr Opin Microbiol 2017; 37:67-78. [PMID: 28605718 DOI: 10.1016/j.mib.2017.05.008] [Citation(s) in RCA: 854] [Impact Index Per Article: 122.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 05/15/2017] [Accepted: 05/28/2017] [Indexed: 01/17/2023]
Abstract
The bacterial and archaeal CRISPR-Cas systems of adaptive immunity show remarkable diversity of protein composition, effector complex structure, genome locus architecture and mechanisms of adaptation, pre-CRISPR (cr)RNA processing and interference. The CRISPR-Cas systems belong to two classes, with multi-subunit effector complexes in Class 1 and single-protein effector modules in Class 2. Concerted genomic and experimental efforts on comprehensive characterization of Class 2 CRISPR-Cas systems led to the identification of two new types and several subtypes. The newly characterized type VI systems are the first among the CRISPR-Cas variants to exclusively target RNA. Unexpectedly, in some of the class 2 systems, the effector protein is additionally responsible for the pre-crRNA processing. Comparative analysis of the effector complexes indicates that Class 2 systems evolved from mobile genetic elements on multiple, independent occasions.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA.
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Feng Zhang
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Cambridge, MA 02139, USA; Departments of Brain and Cognitive Science and Biological Engineering, Cambridge, MA 02139, USA
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33
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Mekler V, Minakhin L, Severinov K. Mechanism of duplex DNA destabilization by RNA-guided Cas9 nuclease during target interrogation. Proc Natl Acad Sci U S A 2017; 114:5443-5448. [PMID: 28484024 PMCID: PMC5448204 DOI: 10.1073/pnas.1619926114] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The prokaryotic clustered regularly interspaced short palindromic repeats (CRISPR)-associated 9 (Cas9) endonuclease cleaves double-stranded DNA sequences specified by guide RNA molecules and flanked by a protospacer adjacent motif (PAM) and is widely used for genome editing in various organisms. The RNA-programmed Cas9 locates the target site by scanning genomic DNA. We sought to elucidate the mechanism of initial DNA interrogation steps that precede the pairing of target DNA with guide RNA. Using fluorometric and biochemical assays, we studied Cas9/guide RNA complexes with model DNA substrates that mimicked early intermediates on the pathway to the final Cas9/guide RNA-DNA complex. The results show that Cas9/guide RNA binding to PAM favors separation of a few PAM-proximal protospacer base pairs allowing initial target interrogation by guide RNA. The duplex destabilization is mediated, in part, by Cas9/guide RNA affinity for unpaired segments of nontarget strand DNA close to PAM. Furthermore, our data indicate that the entry of double-stranded DNA beyond a short threshold distance from PAM into the Cas9/single-guide RNA (sgRNA) interior is hindered. We suggest that the interactions unfavorable for duplex DNA binding promote DNA bending in the PAM-proximal region during early steps of Cas9/guide RNA-DNA complex formation, thus additionally destabilizing the protospacer duplex. The mechanism that emerges from our analysis explains how the Cas9/sgRNA complex is able to locate the correct target sequence efficiently while interrogating numerous nontarget sequences associated with correct PAMs.
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Affiliation(s)
- Vladimir Mekler
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854;
| | - Leonid Minakhin
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854
| | - Konstantin Severinov
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854;
- Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ 08854
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
- Peter the Great State Polytechnical Institute, St. Petersburg 195251, Russia
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34
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Liu TY, Iavarone AT, Doudna JA. RNA and DNA Targeting by a Reconstituted Thermus thermophilus Type III-A CRISPR-Cas System. PLoS One 2017; 12:e0170552. [PMID: 28114398 PMCID: PMC5256923 DOI: 10.1371/journal.pone.0170552] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 01/07/2017] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems are RNA-guided adaptive immunity pathways used by bacteria and archaea to defend against phages and plasmids. Type III-A systems use a multisubunit interference complex called Csm, containing Cas proteins and a CRISPR RNA (crRNA) to target cognate nucleic acids. The Csm complex is intriguing in that it mediates RNA-guided targeting of both RNA and transcriptionally active DNA, but the mechanism is not well understood. Here, we overexpressed the five components of the Thermus thermophilus (T. thermophilus) Type III-A Csm complex (TthCsm) with a defined crRNA sequence, and purified intact TthCsm complexes from E. coli cells. The complexes were thermophilic, targeting complementary ssRNA more efficiently at 65°C than at 37°C. Sequence-independent, endonucleolytic cleavage of single-stranded DNA (ssDNA) by TthCsm was triggered by recognition of a complementary ssRNA, and required a lack of complementarity between the first 8 nucleotides (5′ tag) of the crRNA and the 3′ flanking region of the ssRNA. Mutation of the histidine-aspartate (HD) nuclease domain of the TthCsm subunit, Cas10/Csm1, abolished DNA cleavage. Activation of DNA cleavage was dependent on RNA binding but not cleavage. This leads to a model in which binding of an ssRNA target to the Csm complex would stimulate cleavage of exposed ssDNA in the cell, such as could occur when the RNA polymerase unwinds double-stranded DNA (dsDNA) during transcription. Our findings establish an amenable, thermostable system for more in-depth investigation of the targeting mechanism using structural biology methods, such as cryo-electron microscopy and x-ray crystallography.
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Affiliation(s)
- Tina Y. Liu
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, California, United States of America
| | - Anthony T. Iavarone
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Jennifer A. Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, California, United States of America
- Innovative Genomics Initiative, University of California, Berkeley, California, United States of America
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- California Institute for Quantitative Biosciences, University of California, Berkeley, California, United States of America
- * E-mail:
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