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Xie H, Zhang R, Li Z, Guo R, Li J, Fu Q, Wang X, Zhou Y. Endogenous Type I-C CRISPR-Cas system of Streptococcus equi subsp. zooepidemicus promotes biofilm formation and pathogenicity. Front Microbiol 2024; 15:1417993. [PMID: 38841053 PMCID: PMC11150851 DOI: 10.3389/fmicb.2024.1417993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 05/09/2024] [Indexed: 06/07/2024] Open
Abstract
Streptococcus equi subsp. zooepidemicus (SEZ) is a significant zoonotic pathogen that causes septicemia, meningitis, and mastitis in domestic animals. Recent reports have highlighted high-mortality outbreaks among swine in the United States. Traditionally recognized for its adaptive immune functions, the CRISPR-Cas system has also been implicated in gene regulation, bacterial pathophysiology, virulence, and evolution. The Type I-C CRISPR-Cas system, which is prevalent in SEZ isolates, appears to play a pivotal role in regulating the pathogenicity of SEZ. By constructing a Cas3 mutant strain (ΔCas3) and a CRISPR-deficient strain (ΔCRISPR), we demonstrated that this system significantly promotes biofilm formation and cell adhesion. However, the deficiency in the CRISPR-Cas system did not affect bacterial morphology or capsule production. In vitro studies showed that the CRISPR-Cas system enhances pro-inflammatory responses in RAW264.7 cells. The ΔCas3 and ΔCRISPR mutant strains exhibited reduced mortality rates in mice, accompanied by a decreased bacterial load in specific organs. RNA-seq analysis revealed distinct expression patterns in both mutant strains, with ΔCas3 displaying a broader range of differentially expressed genes, which accounted for over 70% of the differential genes observed in ΔCRISPR. These genes were predominantly linked to lipid metabolism, the ABC transport system, signal transduction, and quorum sensing. These findings enhance our understanding of the complex role of the CRISPR-Cas system in SEZ pathogenesis and provide valuable insights for developing innovative therapeutic strategies to combat infections.
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Affiliation(s)
- Honglin Xie
- Department of Life Science, Nanjing Xiaozhuang University, Nanjing, China
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Riteng Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Ziyuan Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Ruhai Guo
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Junda Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Qiang Fu
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Xinglong Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yefei Zhou
- Department of Life Science, Nanjing Xiaozhuang University, Nanjing, China
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2
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Geslewitz WE, Cardenas A, Zhou X, Zhang Y, Criss AK, Seifert HS. Development and implementation of a Type I-C CRISPR-based programmable repression system for Neisseria gonorrhoeae. mBio 2024; 15:e0302523. [PMID: 38126782 PMCID: PMC10865793 DOI: 10.1128/mbio.03025-23] [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: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) are prokaryotic adaptive immune systems regularly utilized as DNA-editing tools. While Neisseria gonorrhoeae does not have an endogenous CRISPR, the commensal species Neisseria lactamica encodes a functional Type I-C CRISPR-Cas system. We have established an isopropyl β-d-1-thiogalactopyranoside added (IPTG)-inducible, CRISPR interference (CRISPRi) platform based on the N. lactamica Type I-C CRISPR missing the Cas3 nuclease to allow locus-specific transcriptional repression. As proof of principle, we targeted a non-phase-variable version of the opaD gene. We show that CRISPRi can downregulate opaD gene and protein expression, resulting in bacterial inability to stimulate neutrophil oxidative responses and to bind to an N-terminal fragment of CEACAM1. Importantly, we used CRISPRi to effectively knockdown all the transcripts of all 11 opa genes using a five-spacer CRISPR array, allowing control of the entire phase-variable opa family in strain FA1090. We also report that repression is reversible following IPTG removal. Finally, we showed that the Type I-C CRISPRi system can conditionally reduce the expression of two essential genes. This CRISPRi system will allow the interrogation of every Gc gene, essential and non-essential, to study physiology and pathogenesis and aid in antimicrobial development.IMPORTANCEClustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems have proven instrumental in genetically manipulating many eukaryotic and prokaryotic organisms. Despite its usefulness, a CRISPR system had yet to be developed for use in Neisseria gonorrhoeae (Gc), a bacterium that is the main etiological agent of gonorrhea infection. Here, we developed a programmable and IPTG-inducible Type I-C CRISPR interference (CRISPRi) system derived from the commensal species Neisseria lactamica as a gene repression system in Gc. As opposed to generating genetic knockouts, the Type I-C CRISPRi system allows us to block transcription of specific genes without generating deletions in the DNA. We explored the properties of this system and found that a minimal spacer array is sufficient for gene repression while also facilitating efficient spacer reprogramming. Importantly, we also show that we can use CRISPRi to knockdown genes that are essential to Gc that cannot normally be knocked out under laboratory settings. Gc encodes ~800 essential genes, many of which have no predicted function. We predict that this Type I-C CRISPRi system can be used to help categorize gene functions and perhaps contribute to the development of novel therapeutics for gonorrhea.
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Affiliation(s)
- Wendy E. Geslewitz
- Department of Microbiology and Immunology, Northwestern University, Chicago, Illinois, USA
| | - Amaris Cardenas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Xufei Zhou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Yan Zhang
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - H Steven Seifert
- Department of Microbiology and Immunology, Northwestern University, Chicago, Illinois, USA
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3
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Hu C, Myers MT, Zhou X, Hou Z, Lozen ML, Nam KH, Zhang Y, Ke A. Exploiting activation and inactivation mechanisms in type I-C CRISPR-Cas3 for genome-editing applications. Mol Cell 2024; 84:463-475.e5. [PMID: 38242128 PMCID: PMC10857747 DOI: 10.1016/j.molcel.2023.12.034] [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: 06/20/2023] [Revised: 10/26/2023] [Accepted: 12/21/2023] [Indexed: 01/21/2024]
Abstract
Type I CRISPR-Cas systems utilize the RNA-guided Cascade complex to identify matching DNA targets and the nuclease-helicase Cas3 to degrade them. Among the seven subtypes, type I-C is compact in size and highly active in creating large-sized genome deletions in human cells. Here, we use four cryoelectron microscopy snapshots to define its RNA-guided DNA binding and cleavage mechanisms in high resolution. The non-target DNA strand (NTS) is accommodated by I-C Cascade in a continuous binding groove along the juxtaposed Cas11 subunits. Binding of Cas3 further traps a flexible bulge in NTS, enabling NTS nicking. We identified two anti-CRISPR proteins AcrIC8 and AcrIC9 that strongly inhibit Neisseria lactamica I-C function. Structural analysis showed that AcrIC8 inhibits PAM recognition through allosteric inhibition, whereas AcrIC9 achieves so through direct competition. Both Acrs potently inhibit I-C-mediated genome editing and transcriptional modulation in human cells, providing the first off-switches for type I CRISPR eukaryotic genome engineering.
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Affiliation(s)
- Chunyi Hu
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA; Department of Biological Sciences, Faculty of Science; Department of Biochemistry, Precision Medicine Translational Research Programme (TRP), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Mason T Myers
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xufei Zhou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Zhonggang Hou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Macy L Lozen
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ki Hyun Nam
- College of General Education, Kookmin University, Seoul 02707, Republic of Korea
| | - Yan Zhang
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
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4
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Anand V, Prabhakaran HS, Prakash A, Hussain MS, Kumar M. Differential processing of CRISPR RNA by LinCas5c and LinCas6 of Leptospira. Biochim Biophys Acta Gen Subj 2023; 1867:130469. [PMID: 37797871 DOI: 10.1016/j.bbagen.2023.130469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023]
Abstract
Leptospira interrogans serovar Copenhageni's genome harbors two CRISPR-Cas systems belonging to subtypes I-B and I-C. However, in L. interrogans, the subtype I-C locus lacks an array component essential for assembling an interference complex. Thus, the reason for sustaining the expense of a cluster of cas genes (I-C) is obscure. Type I-C (previously Dvulg) is the only CRISPR subtype that engages Cas5c, a Cas5 variant, to process precursor CRISPR-RNA (pre-crRNA). In this study, thus, the recombinant Cas5c (rLinCas5c) of L.interrogans and its mutant variants were cloned, expressed, and purified. The purified rLinCas5c is illustrated as metal-independent, sequence, and size-specific cleavage on repeat RNA and pre-crRNA of subtype I-B or orphan CRISPR array. However, the Cas6-bound mature crRNA of subtype I-B fends off from the rLinCas5c activity. In addition, rLinCas5c holds metal and size-dependent DNase activity. The bioinformatics analysis of LinCas5c inferred that it belongs to the subgroup Cas5c-B. Substitution of Phe141 with a more conserved His residue and deletion of unique (β1'-β2') insertions usher a gain of rLinCas5c activity over nucleic acid. Overall, our results uncover the functional diversity of Cas5c ribonucleases and infer an incognito auxiliary role in the absence of a cognate CRISPR array.
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Affiliation(s)
- Vineet Anand
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Harshini Sheeja Prabhakaran
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Aman Prakash
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Md Saddam Hussain
- 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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5
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Oh H, Koo J, An SY, Hong SH, Suh JY, Bae E. Structural and functional investigation of GajB protein in Gabija anti-phage defense. Nucleic Acids Res 2023; 51:11941-11951. [PMID: 37897358 PMCID: PMC10681800 DOI: 10.1093/nar/gkad951] [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: 06/01/2023] [Revised: 09/13/2023] [Accepted: 10/12/2023] [Indexed: 10/30/2023] Open
Abstract
Bacteriophages (phages) are viruses that infect bacteria and archaea. To fend off invading phages, the hosts have evolved a variety of anti-phage defense mechanisms. Gabija is one of the most abundant prokaryotic antiviral systems and consists of two proteins, GajA and GajB. GajA has been characterized experimentally as a sequence-specific DNA endonuclease. Although GajB was previously predicted to be a UvrD-like helicase, its function is unclear. Here, we report the results of structural and functional analyses of GajB. The crystal structure of GajB revealed a UvrD-like domain architecture, including two RecA-like core and two accessory subdomains. However, local structural elements that are important for the helicase function of UvrD are not conserved in GajB. In functional assays, GajB did not unwind or bind various types of DNA substrates. We demonstrated that GajB interacts with GajA to form a heterooctameric Gabija complex, but GajB did not exhibit helicase activity when bound to GajA. These results advance our understanding of the molecular mechanism underlying Gabija anti-phage defense and highlight the role of GajB as a component of a multi-subunit antiviral complex in bacteria.
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Affiliation(s)
- Hyejin Oh
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
| | - Jasung Koo
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
| | - So Young An
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Sung-Hyun Hong
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Jeong-Yong Suh
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Euiyoung Bae
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
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6
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Li Y, Huang B, Chen J, Huang L, Xu J, Wang Y, Cui G, Zhao H, Xin B, Song W, Zhu J, Lai J. Targeted large fragment deletion in plants using paired crRNAs with type I CRISPR system. PLANT BIOTECHNOLOGY JOURNAL 2023; 21:2196-2208. [PMID: 37641539 PMCID: PMC10579709 DOI: 10.1111/pbi.14122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/19/2023] [Accepted: 06/25/2023] [Indexed: 08/31/2023]
Abstract
The CRISPR-Cas systems have been widely used as genome editing tools, with type II and V systems typically introducing small indels, and type I system mediating long-range deletions. However, the precision of type I systems for large fragment deletion is still remained to be optimized. Here, we developed a compact Cascade-Cas3 Dvu I-C system with Cas11c for plant genome editing. The Dvu I-C system was efficient to introduce controllable large fragment deletion up to at least 20 kb using paired crRNAs. The paired-crRNAs design also improved the controllability of deletions for the type I-E system. Dvu I-C system was sensitive to spacer length and mismatch, which was benefit for target specificity. In addition, we showed that the Dvu I-C system was efficient for generating stable transgenic lines in maize and rice with the editing efficiency up to 86.67%. Overall, Dvu I-C system we developed here is powerful for achieving controllable large fragment deletions.
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Affiliation(s)
- Yingnan Li
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Boyu Huang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jian Chen
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Liangliang Huang
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Jianghai Xu
- College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Yingying Wang
- College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Guanghui Cui
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Haiming Zhao
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Beibei Xin
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Weibin Song
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
| | - Jian‐Kang Zhu
- Institute of Advanced Biotechnology and School of Life SciencesSouthern University of Science and TechnologyShenzhenChina
- Center for Advanced Bioindustry TechnologiesChinese Academy of Agricultural SciencesBeijingChina
| | - Jinsheng Lai
- State Key Laboratory of Maize Bio‐breeding, National Maize Improvement Center, Department of Plant Genetics and BreedingChina Agricultural UniversityBeijingChina
- Frontiers Science Center for Molecular Design BreedingChina Agricultural UniversityBeijingChina
- Center for Crop Functional Genomics and Molecular BreedingChina Agricultural UniversityBeijingChina
- Sanya Institute of China Agricultural UniversitySanyaChina
- Hainan Yazhou Bay Seed LaboratorySanyaChina
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7
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Hu C, Myers MT, Zhou X, Hou Z, Lozen ML, Zhang Y, Ke A. Exploiting Activation and Inactivation Mechanisms in Type I-C CRISPR-Cas3 for Genome Editing Applications. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.05.552134. [PMID: 37577534 PMCID: PMC10418205 DOI: 10.1101/2023.08.05.552134] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Type I CRISPR-Cas systems utilize the RNA-guided Cascade complex to identify matching DNA targets, and the nuclease-helicase Cas3 to degrade them. Among seven subtypes, Type I-C is compact in size and highly active in creating large-sized genome deletions in human cells. Here we use four cryo-electron microscopy snapshots to define its RNA-guided DNA binding and cleavage mechanisms in high resolution. The non-target DNA strand (NTS) is accommodated by I-C Cascade in a continuous binding groove along the juxtaposed Cas11 subunits. Binding of Cas3 further traps a flexible bulge in NTS, enabling efficient NTS nicking. We identified two anti-CRISPR proteins AcrIC8 and AcrIC9, that strongly inhibit N. lactamica I-C function. Structural analysis showed that AcrIC8 inhibits PAM recognition through direct competition, whereas AcrIC9 achieves so through allosteric inhibition. Both Acrs potently inhibit I-C-mediated genome editing and transcriptional modulation in human cells, providing the first off-switches for controllable Type I CRISPR genome engineering.
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8
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Brenner E, Sreevatsan S. Cold Cas: reevaluating the occurrence of CRISPR/Cas systems in Mycobacteriaceae. Front Microbiol 2023; 14:1204838. [PMID: 37440893 PMCID: PMC10333696 DOI: 10.3389/fmicb.2023.1204838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 05/22/2023] [Indexed: 07/15/2023] Open
Abstract
Bacterial CRISPR/Cas systems target foreign genetic elements such as phages and regulate gene expression by some pathogens, even in the host. The system is a marker for evolutionary history and has been used for inferences in Mycobacterium tuberculosis for 30 years. However, knowledge about mycobacterial CRISPR/Cas systems remains limited. It is believed that Type III-A Cas systems are exclusive to Mycobacterium canettii and the M. tuberculosis complex (MTBC) of organisms and that very few of the >200 diverse species of non-tuberculous mycobacteria (NTM) possess any CRISPR/Cas system. This study sought unreported CRISPR/Cas loci across NTM to better understand mycobacterial evolution, particularly in species phylogenetically near the MTBC. An analysis of available mycobacterial genomes revealed that Cas systems are widespread across Mycobacteriaceae and that some species contain multiple types. The phylogeny of Cas loci shows scattered presence in many NTM, with variation even within species, suggesting gains/losses of these loci occur frequently. Cas Type III-A systems were identified in pathogenic Mycobacterium heckeshornense and the geological environmental isolate Mycobacterium SM1. In summary, mycobacterial CRISPR/Cas systems are numerous, Type III-A systems are unreliable as markers for MTBC evolution, and mycobacterial horizontal gene transfer appears to be a frequent source of genetic variation.
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Affiliation(s)
| | - Srinand Sreevatsan
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI, United States
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9
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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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10
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O'Brien RE, Bravo JPK, Ramos D, Hibshman GN, Wright JT, Taylor DW. Structural snapshots of R-loop formation by a type I-C CRISPR Cascade. Mol Cell 2023; 83:746-758.e5. [PMID: 36805026 PMCID: PMC10026943 DOI: 10.1016/j.molcel.2023.01.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 12/12/2022] [Accepted: 01/26/2023] [Indexed: 02/18/2023]
Abstract
Type I CRISPR-Cas systems employ multi-subunit Cascade effector complexes to target foreign nucleic acids for destruction. Here, we present structures of D. vulgaris type I-C Cascade at various stages of double-stranded (ds)DNA target capture, revealing mechanisms that underpin PAM recognition and Cascade allosteric activation. We uncover an interesting mechanism of non-target strand (NTS) DNA stabilization via stacking interactions with the "belly" subunits, securing the NTS in place. This "molecular seatbelt" mechanism facilitates efficient R-loop formation and prevents dsDNA reannealing. Additionally, we provide structural insights into how two anti-CRISPR (Acr) proteins utilize distinct strategies to achieve a shared mechanism of type I-C Cascade inhibition by blocking PAM scanning. These observations form a structural basis for directional R-loop formation and reveal how different Acr proteins have converged upon common molecular mechanisms to efficiently shut down CRISPR immunity.
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Affiliation(s)
- Roisin E O'Brien
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX 78712, USA
| | - Jack P K Bravo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Delisa Ramos
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Grace N Hibshman
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX 78712, USA
| | - Jacquelyn T Wright
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX 78712, USA
| | - David W Taylor
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX 78712, USA; 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; LIVESTRONG Cancer Institutes, Dell Medical School, University of Texas at Austin, Austin, TX 78712, USA.
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11
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Rasmussen TS, Koefoed AK, Deng L, Muhammed MK, Rousseau GM, Kot W, Sprotte S, Neve H, Franz CMAP, Hansen AK, Vogensen FK, Moineau S, Nielsen DS. CRISPR-Cas provides limited phage immunity to a prevalent gut bacterium in gnotobiotic mice. THE ISME JOURNAL 2023; 17:432-442. [PMID: 36631688 PMCID: PMC9938214 DOI: 10.1038/s41396-023-01358-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023]
Abstract
Many bacteria and archaea harbor the adaptive CRISPR-Cas system, which stores small nucleotide fragments from previous invasions of nucleic acids via viruses or plasmids. This molecular archive blocks further invaders carrying identical or similar nucleotide sequences. However, few of these systems have been confirmed experimentally to be active in gut bacteria. Here, we demonstrate experimentally that the type I-C CRISPR-Cas system of the prevalent gut bacterium Eggerthella lenta can specifically target and cleave foreign DNA in vitro by using a plasmid transformation assay. We also show that the CRISPR-Cas system acquires new immunities (spacers) from the genome of a virulent E. lenta phage using traditional phage assays in vitro but also in vivo using gnotobiotic (GB) mice. Both high phage titer and an increased number of spacer acquisition events were observed when E. lenta was exposed to a low multiplicity of infection in vitro, and three phage genes were found to contain protospacer hotspots. Fewer new spacer acquisitions were detected in vivo than in vitro. Longitudinal analysis of phage-bacteria interactions showed sustained coexistence in the gut of GB mice, with phage abundance being approximately one log higher than the bacteria. Our findings show that while the type I-C CRISPR-Cas system is active in vitro and in vivo, a highly virulent phage in vitro was still able to co-exist with its bacterial host in vivo. Taken altogether, our results suggest that the CRISPR-Cas defense system of E. lenta provides only partial immunity in the gut.
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Affiliation(s)
- Torben Sølbeck Rasmussen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark.
| | - Anna Kirstine Koefoed
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Ling Deng
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Musemma K Muhammed
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Geneviève M Rousseau
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de 1enie, Université Laval, Québec, QC, G1V 0A6, Canada
- Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Witold Kot
- Section of Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
| | - Sabrina Sprotte
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Horst Neve
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Charles M A P Franz
- Department of Microbiology and Biotechnology, Max Rubner-Institut, 24103, Kiel, Germany
| | - Axel Kornerup Hansen
- Section of Experimental Animal Models, Department of Veterinary and Animal Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
| | - Finn Kvist Vogensen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark
| | - Sylvain Moineau
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de 1enie, Université Laval, Québec, QC, G1V 0A6, Canada
- Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
- Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de médecine dentaire, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Dennis Sandris Nielsen
- Section of Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, 1958, Frederiksberg, Denmark.
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12
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Bravo JP, Hibshman GN, Taylor DW. Constructing next-generation CRISPR-Cas tools from structural blueprints. Curr Opin Biotechnol 2022; 78:102839. [PMID: 36371895 DOI: 10.1016/j.copbio.2022.102839] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/18/2022] [Accepted: 10/10/2022] [Indexed: 11/12/2022]
Abstract
Clustered regularly interspaced short palindromic repeats - CRISPR-associated protein (CRISPR-Cas) systems are a critical component of the bacterial adaptive immune response. Since the discovery that they can be reengineered as programmable RNA-guided nucleases, there has been significant interest in using these systems to perform diverse and precise genetic manipulations. Here, we outline recent advances in the mechanistic understanding of CRISPR-Cas9, how these findings have been leveraged in the rational redesign of Cas9 variants with altered activities, and how these novel tools can be exploited for biotechnology and therapeutics. We also discuss the potential of the ubiquitous, yet often-overlooked, multisubunit CRISPR effector complexes for large-scale genomic deletions. Furthermore, we highlight how future structural studies will bolster these technologies.
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Affiliation(s)
- Jack Pk Bravo
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA.
| | - Grace N Hibshman
- Interdisciplinary Life Sciences Graduate Program, The University of Texas at Austin, Austin, TX, USA
| | - David W Taylor
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA; Interdisciplinary Life Sciences Graduate Program, The University of Texas at Austin, Austin, TX, USA; Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA; Livestrong Cancer Institutes, Dell Medical School, Austin, TX, USA
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13
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Shangguan Q, Graham S, Sundaramoorthy R, White M. Structure and mechanism of the type I-G CRISPR effector. Nucleic Acids Res 2022; 50:11214-11228. [PMID: 36305833 PMCID: PMC9638904 DOI: 10.1093/nar/gkac925] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/28/2022] [Accepted: 10/07/2022] [Indexed: 08/15/2023] Open
Abstract
Type I CRISPR systems are the most common CRISPR type found in bacteria. They use a multisubunit effector, guided by crRNA, to detect and bind dsDNA targets, forming an R-loop and recruiting the Cas3 enzyme to facilitate target DNA destruction, thus providing immunity against mobile genetic elements. Subtypes have been classified into families A-G, with type I-G being the least well understood. Here, we report the composition, structure and function of the type I-G Cascade CRISPR effector from Thioalkalivibrio sulfidiphilus, revealing key new molecular details. The unique Csb2 subunit processes pre-crRNA, remaining bound to the 3' end of the mature crRNA, and seven Cas7 subunits form the backbone of the effector. Cas3 associates stably with the effector complex via the Cas8g subunit and is important for target DNA recognition. Structural analysis by cryo-Electron Microscopy reveals a strikingly curved backbone conformation with Cas8g spanning the belly of the structure. These biochemical and structural insights shed new light on the diversity of type I systems and open the way to applications in genome engineering.
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Affiliation(s)
- Qilin Shangguan
- School of Biology, University of St Andrews, St Andrews, Fife KY16 9ST, UK
| | - Shirley Graham
- School of Biology, University of St Andrews, St Andrews, Fife KY16 9ST, UK
| | | | - Malcolm F White
- School of Biology, University of St Andrews, St Andrews, Fife KY16 9ST, UK
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14
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Hu C, Ni D, Nam KH, Majumdar S, McLean J, Stahlberg H, Terns MP, Ke A. Allosteric control of type I-A CRISPR-Cas3 complexes and establishment as effective nucleic acid detection and human genome editing tools. Mol Cell 2022; 82:2754-2768.e5. [PMID: 35835111 PMCID: PMC9357151 DOI: 10.1016/j.molcel.2022.06.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/08/2022] [Accepted: 06/06/2022] [Indexed: 12/26/2022]
Abstract
Type I CRISPR-Cas systems typically rely on a two-step process to degrade DNA. First, an RNA-guided complex named Cascade identifies the complementary DNA target. The helicase-nuclease fusion enzyme Cas3 is then recruited in trans for processive DNA degradation. Contrary to this model, here, we show that type I-A Cascade and Cas3 function as an integral effector complex. We provide four cryoelectron microscopy (cryo-EM) snapshots of the Pyrococcus furiosus (Pfu) type I-A effector complex in different stages of DNA recognition and degradation. The HD nuclease of Cas3 is autoinhibited inside the effector complex. It is only allosterically activated upon full R-loop formation, when the entire targeted region has been validated by the RNA guide. The mechanistic insights inspired us to convert Pfu Cascade-Cas3 into a high-sensitivity, low-background, and temperature-activated nucleic acid detection tool. Moreover, Pfu CRISPR-Cas3 shows robust bi-directional deletion-editing activity in human cells, which could find usage in allele-specific inactivation of disease-causing mutations.
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Affiliation(s)
- Chunyi Hu
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA
| | - Dongchun Ni
- Laboratory of Biological Electron Microscopy, Institute of Physics, Faculty of Basic Sciences, Swiss Federal Institute of Technology (EPFL), Cubotron, Route de la Sorge, 1015 Lausanne, Switzerland; Department of Fundamental Biology, Faculty of Biology and Medicine, University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Ki Hyun Nam
- Department of Life Science, Pohang University of Science and Technology, Pohang, Gyeongbuk, Republic of Korea
| | - Sonali Majumdar
- Department of Biochemistry and Molecular Biology, Department of Genetics, and Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Justin McLean
- Department of Biochemistry and Molecular Biology, Department of Genetics, and Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Henning Stahlberg
- Laboratory of Biological Electron Microscopy, Institute of Physics, Faculty of Basic Sciences, Swiss Federal Institute of Technology (EPFL), Cubotron, Route de la Sorge, 1015 Lausanne, Switzerland; Department of Fundamental Biology, Faculty of Biology and Medicine, University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Michael P Terns
- Department of Biochemistry and Molecular Biology, Department of Genetics, and Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, 253 Biotechnology Building, Ithaca, NY 14853, USA.
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15
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Rapid Hypothesis Testing in Candida albicans Clinical Isolates Using a Cloning-Free, Modular, and Recyclable System for CRISPR-Cas9 Mediated Mutant and Revertant Construction. Microbiol Spectr 2022; 10:e0263021. [PMID: 35612314 PMCID: PMC9241802 DOI: 10.1128/spectrum.02630-21] [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] [Indexed: 11/20/2022] Open
Abstract
As increasing evidence emerges that interstrain genetic diversity among Candida albicans clinical isolates underpins phenotypic variation compared to the reference isolate SC5314, new genetic tools are required to interrogate gene function across strain backgrounds. Here, the SAT1-flipper plasmid was reengineered to contain a C. albicans codon optimized hygromycin B resistance gene (CaHygB). Cassettes were PCR-amplified from both SAT1-flipper and CaHygB-flipper plasmids using primers with homologous sequences flanking target genes of interest to serve as repair templates. Ribonucleoprotein (RNP) complexes containing proprietary CRISPR RNAs (crRNAs), universal transactivating CRISPR RNA (tracrRNA), and Cas9 protein were assembled in vitro and transformed, along with both repair templates, by electroporation into C. albicans. Homozygous deletion of the ADE2 gene results in red-pigmented colonies and this gene was used to validate our approach. Both in SC5314 and a variety of clinical isolates (529L, JS15, SJCA1, TW1), homozygous gene targeting was nearly 100% when plating on media containing nourseothricin and hygromycin B with transformation efficiencies exceeding 104 homozygous deletion mutants per μg of DNA. A gene reversion system was also employed with plasmids pDUP3 and pDIS3 engineered to contain the ADH1 terminator and an overlap extension PCR-mediated approach combined with CRISPR-Cas9 targeting at the NEUT5 neutral locus. A variety of single or compound mutants (Δ/Δals3, Δ/Δcph1 Δ/Δefg1, Δ/Δece1) and their revertant strains were constructed and phenotypically validated by a variety of assays, including biofilm formation, hyphal growth, and macrophage IL-1β response. Thus, we have established a cloning-free, modular system for highly efficient homozygous gene deletion and reversion in diverse isolates. IMPORTANCE Recently, phenotypic heterogeneity in Candida albicans isolates has been recognized as an underappreciated factor contributing to gene diversification and broadly impacts strain-to-strain antifungal resistance, fitness, and pathogenicity. We have designed a cloning-free genetic system for rapid gene deletion and reversion in C. albicans clinical isolates that interlaces established recyclable genetic systems with CRISPR-Cas9 technology. The SAT1-flipper was reengineered to contain CaHygB encoding resistance to hygromycin B. Using a modular PCR-mediated approach coupled with in vitro ribonucleoprotein assembly with commercial reagents, both SAT1- and CaHygB-flipper cassettes were simultaneously integrated at loci with high efficiency (104 transformants per μg DNA) and upward of 99% homozygous gene targeting across a collection of diverse isolates of various anatomical origin. Revertant strains were constructed by overlap extension PCR with CRISPR-Cas9 targeted integration at the NEUT5 locus. Thus, this facile system will aid in unraveling the genetic factors contributing to the complexity of intraspecies diversity.
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16
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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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17
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Cofsky JC, Soczek KM, Knott GJ, Nogales E, Doudna JA. CRISPR-Cas9 bends and twists DNA to read its sequence. Nat Struct Mol Biol 2022; 29:395-402. [PMID: 35422516 PMCID: PMC9189902 DOI: 10.1038/s41594-022-00756-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/01/2022] [Indexed: 12/28/2022]
Abstract
In bacterial defense and genome editing applications, the CRISPR-associated protein Cas9 searches millions of DNA base pairs to locate a 20-nucleotide, guide RNA-complementary target sequence that abuts a protospacer-adjacent motif (PAM). Target capture requires Cas9 to unwind DNA at candidate sequences using an unknown ATP-independent mechanism. Here we show that Cas9 sharply bends and undertwists DNA on PAM binding, thereby flipping DNA nucleotides out of the duplex and toward the guide RNA for sequence interrogation. Cryogenic-electron microscopy (cryo-EM) structures of Cas9-RNA-DNA complexes trapped at different states of the interrogation pathway, together with solution conformational probing, reveal that global protein rearrangement accompanies formation of an unstacked DNA hinge. Bend-induced base flipping explains how Cas9 'reads' snippets of DNA to locate target sites within a vast excess of nontarget DNA, a process crucial to both bacterial antiviral immunity and genome editing. This mechanism establishes a physical solution to the problem of complementarity-guided DNA search and shows how interrogation speed and local DNA geometry may influence genome editing efficiency.
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Affiliation(s)
- Joshua C Cofsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Katarzyna M Soczek
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Gavin J Knott
- Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, USA.
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA.
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Gladstone Institutes, University of California, San Francisco, CA, USA.
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA.
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18
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Jiang D, Zhang D, Li S, Liang Y, Zhang Q, Qin X, Gao J, Qiu J. Highly efficient genome editing in Xanthomonas oryzae pv. oryzae through repurposing the endogenous type I-C CRISPR-Cas system. MOLECULAR PLANT PATHOLOGY 2022; 23:583-594. [PMID: 34954876 PMCID: PMC8916207 DOI: 10.1111/mpp.13178] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/25/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
Efficient and modular genome editing technologies that manipulate the genome of bacterial pathogens will facilitate the study of pathogenesis mechanisms. However, such methods are yet to be established for Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight. We identified a single type I-C CRISPR-Cas system in the Xoo genome and leveraged this endogenous defence system for high-efficiency genome editing in Xoo. Specifically, we developed plasmid components carrying a mini-CRISPR array, donor DNA, and a phage-derived recombination system to enable the efficient and programmable genome editing of precise deletions, insertions, base substitutions, and gene replacements. Furthermore, the type I-C CRISPR-Cas system of Xoo cleaves target DNA unidirectionally, and this can be harnessed to generate large genomic deletions up to 212 kb efficiently. Therefore, the genome-editing strategy we have developed can serve as an excellent tool for functional genomics of Xoo, and should also be applicable to other CRISPR-harbouring bacterial plant pathogens.
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Affiliation(s)
- Dandan Jiang
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Center for Excellence in Biotic InteractionsUniversity of Chinese Academy of SciencesBeijingChina
| | - Dandan Zhang
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Shengnan Li
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Yueting Liang
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Center for Excellence in Biotic InteractionsUniversity of Chinese Academy of SciencesBeijingChina
| | - Qianwei Zhang
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Center for Excellence in Biotic InteractionsUniversity of Chinese Academy of SciencesBeijingChina
| | - Xu Qin
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Center for Excellence in Biotic InteractionsUniversity of Chinese Academy of SciencesBeijingChina
| | - Jinlan Gao
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
| | - Jin‐Long Qiu
- State Key Laboratory of Plant GenomicsInstitute of MicrobiologyChinese Academy of SciencesBeijingChina
- CAS Center for Excellence in Biotic InteractionsUniversity of Chinese Academy of SciencesBeijingChina
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19
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Tan R, Krueger RK, Gramelspacher MJ, Zhou X, Xiao Y, Ke A, Hou Z, Zhang Y. Cas11 enables genome engineering in human cells with compact CRISPR-Cas3 systems. Mol Cell 2022; 82:852-867.e5. [PMID: 35051351 PMCID: PMC8964063 DOI: 10.1016/j.molcel.2021.12.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 11/09/2021] [Accepted: 12/21/2021] [Indexed: 11/28/2022]
Abstract
Leading CRISPR-Cas technologies employ Cas9 and Cas12 enzymes that generate RNA-guided dsDNA breaks. Yet, the most abundant microbial adaptive immune systems, Type I CRISPRs, are under-exploited for eukaryotic applications. Here, we report the adoption of a minimal CRISPR-Cas3 from Neisseria lactamica (Nla) type I-C system to create targeted large deletions in the human genome. RNP delivery of its processive Cas3 nuclease and target recognition complex Cascade can confer ∼95% editing efficiency. Unexpectedly, NlaCascade assembly in bacteria requires internal translation of a hidden component Cas11 from within the cas8 gene. Furthermore, expressing a separately encoded NlaCas11 is the key to enable plasmid- and mRNA-based editing in human cells. Finally, we demonstrate that supplying cas11 is a universal strategy to systematically implement divergent I-C, I-D, and I-B CRISPR-Cas3 editors with compact sizes, distinct PAM preferences, and guide orthogonality. These findings greatly expand our ability to engineer long-range genome edits.
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Affiliation(s)
- Renke Tan
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA,These authors contributed equally
| | - Ryan K Krueger
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA,These authors contributed equally
| | - Max J Gramelspacher
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Xufei Zhou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Yibei Xiao
- State Key Laboratory of Natural Medicines, Department of Pharmacology, China Pharmaceutical University, Nanjing, China
| | - Ailong Ke
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Zhonggang Hou
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.
| | - Yan Zhang
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.
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20
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Wimmer F, Mougiakos I, Englert F, Beisel CL. Rapid cell-free characterization of multi-subunit CRISPR effectors and transposons. Mol Cell 2022; 82:1210-1224.e6. [PMID: 35216669 DOI: 10.1016/j.molcel.2022.01.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/30/2021] [Accepted: 01/26/2022] [Indexed: 11/25/2022]
Abstract
CRISPR-Cas biology and technologies have been largely shaped to date by the characterization and use of single-effector nucleases. By contrast, multi-subunit effectors dominate natural systems, represent emerging technologies, and were recently associated with RNA-guided DNA transposition. This disconnect stems from the challenge of working with multiple protein subunits in vitro and in vivo. Here, we apply cell-free transcription-translation (TXTL) systems to radically accelerate the characterization of multi-subunit CRISPR effectors and transposons. Numerous DNA constructs can be combined in one TXTL reaction, yielding defined biomolecular readouts in hours. Using TXTL, we mined phylogenetically diverse I-E effectors, interrogated extensively self-targeting I-C and I-F systems, and elucidated targeting rules for I-B and I-F CRISPR transposons using only DNA-binding components. We further recapitulated DNA transposition in TXTL, which helped reveal a distinct branch of I-B CRISPR transposons. These capabilities will facilitate the study and exploitation of the broad yet underexplored diversity of CRISPR-Cas systems and transposons.
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Affiliation(s)
- Franziska Wimmer
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Ioannis Mougiakos
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Frank Englert
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Chase L Beisel
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany; Medical Faculty, University of Würzburg, 97080 Würzburg, Germany.
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21
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Hu C, Ke A. Reconstitution and biochemical characterization of the RNA-guided helicase-nuclease protein Cas3 from type I-A CRISPR–Cas system. Methods Enzymol 2022; 673:405-424. [DOI: 10.1016/bs.mie.2022.03.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Lemak S, Serbanescu MA, Khusnutdinova AN, Ruszkowski M, Beloglazova N, Xu X, Brown G, Cui H, Tan K, Joachimiak A, Cvitkovitch DG, Savchenko A, Yakunin AF. Structural and biochemical insights into CRISPR RNA processing by the Cas5c ribonuclease SMU1763 from Streptococcus mutans. J Biol Chem 2021; 297:101251. [PMID: 34592310 PMCID: PMC8524198 DOI: 10.1016/j.jbc.2021.101251] [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: 04/01/2021] [Revised: 09/13/2021] [Accepted: 09/24/2021] [Indexed: 12/01/2022] Open
Abstract
The cariogenic pathogen Streptococcus mutans contains two CRISPR systems (type I-C and type II-A) with the Cas5c protein (SmuCas5c) involved in processing of long CRISPR RNA transcripts (pre-crRNA) containing repeats and spacers to mature crRNA guides. In this study, we determined the crystal structure of SmuCas5c at a resolution of 1.72 Å, which revealed the presence of an N-terminal modified RNA recognition motif and a C-terminal twisted β-sheet domain with four bound sulphate molecules. Analysis of surface charge and residue conservation of the SmuCas5c structure suggested the location of an RNA-binding site in a shallow groove formed by the RNA recognition motif domain with several conserved positively charged residues (Arg39, Lys52, Arg109, Arg127, and Arg134). Purified SmuCas5c exhibited metal-independent ribonuclease activity against single-stranded pre-CRISPR RNAs containing a stem-loop structure with a seven-nucleotide stem and a pentaloop. We found SmuCas5c cleaves substrate RNA within the repeat sequence at a single cleavage site located at the 3'-base of the stem but shows significant tolerance to substrate sequence variations downstream of the cleavage site. Structure-based mutational analysis revealed that the conserved residues Tyr50, Lys120, and His121 comprise the SmuCas5c catalytic residues. In addition, site-directed mutagenesis of positively charged residues Lys52, Arg109, and Arg134 located near the catalytic triad had strong negative effects on the RNase activity of this protein, suggesting that these residues are involved in RNA binding. Taken together, our results reveal functional diversity of Cas5c ribonucleases and provide further insight into the molecular mechanisms of substrate selectivity and activity of these enzymes.
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Affiliation(s)
- Sofia Lemak
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - M Anca Serbanescu
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Anna N Khusnutdinova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Milosz Ruszkowski
- Synchrotron Radiation Research Section of MCL, National Cancer Institute, Argonne, Illinois, USA
| | - Natalia Beloglazova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Xiaohui Xu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Greg Brown
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Hong Cui
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Kemin Tan
- X-Ray Science Division, Midwest Center for Structural Genomics and Structural Biology Center, Argonne National Laboratory, Argonne, Illinois, USA
| | - Andrzej Joachimiak
- X-Ray Science Division, Midwest Center for Structural Genomics and Structural Biology Center, Argonne National Laboratory, Argonne, Illinois, USA
| | - Dennis G Cvitkovitch
- Faculty of Dentistry, Dental Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada; Centre for Environmental Biotechnology, School of Natural Sciences, Bangor University, Bangor, Gwynedd, UK.
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23
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Osakabe K, Wada N, Murakami E, Miyashita N, Osakabe Y. Genome editing in mammalian cells using the CRISPR type I-D nuclease. Nucleic Acids Res 2021; 49:6347-6363. [PMID: 34076237 PMCID: PMC8216271 DOI: 10.1093/nar/gkab348] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 04/15/2021] [Accepted: 05/20/2021] [Indexed: 12/26/2022] Open
Abstract
Adoption of CRISPR-Cas systems, such as CRISPR-Cas9 and CRISPR-Cas12a, has revolutionized genome engineering in recent years; however, application of genome editing with CRISPR type I-the most abundant CRISPR system in bacteria-remains less developed. Type I systems, such as type I-E, and I-F, comprise the CRISPR-associated complex for antiviral defense ('Cascade': Cas5, Cas6, Cas7, Cas8 and the small subunit) and Cas3, which degrades the target DNA; in contrast, for the sub-type CRISPR-Cas type I-D, which lacks a typical Cas3 nuclease in its CRISPR locus, the mechanism of target DNA degradation remains unknown. Here, we found that Cas10d is a functional nuclease in the type I-D system, performing the role played by Cas3 in other CRISPR-Cas type I systems. The type I-D system can be used for targeted mutagenesis of genomic DNA in human cells, directing both bi-directional long-range deletions and short insertions/deletions. Our findings suggest the CRISPR-Cas type I-D system as a unique effector pathway in CRISPR that can be repurposed for genome engineering in eukaryotic cells.
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Affiliation(s)
- Keishi Osakabe
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Tokushima 770-8503, Japan
| | - Naoki Wada
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Tokushima 770-8503, Japan
| | - Emi Murakami
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Tokushima 770-8503, Japan
| | - Naoyuki Miyashita
- Department of Computational Systems Biology, Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama 649-6493, Japan
| | - Yuriko Osakabe
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Tokushima 770-8503, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8502, Japan
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24
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Zhou Y, Bravo JP, Taylor HN, Steens JA, Jackson RN, Staals RH, Taylor DW. Structure of a type IV CRISPR-Cas ribonucleoprotein complex. iScience 2021; 24:102201. [PMID: 33733066 PMCID: PMC7937560 DOI: 10.1016/j.isci.2021.102201] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 01/03/2021] [Accepted: 02/12/2021] [Indexed: 12/18/2022] Open
Abstract
We reveal the cryo-electron microscopy structure of a type IV-B CRISPR ribonucleoprotein (RNP) complex (Csf) at 3.9-Å resolution. The complex best resembles the type III-A CRISPR Csm effector complex, consisting of a Cas7-like (Csf2) filament intertwined with a small subunit (Cas11) filament, but the complex lacks subunits for RNA processing and target DNA cleavage. Surprisingly, instead of assembling around a CRISPR-derived RNA (crRNA), the complex assembles upon heterogeneous RNA of a regular length arranged in a pseudo-A-form configuration. These findings provide a high-resolution glimpse into the assembly and function of enigmatic type IV CRISPR systems, expanding our understanding of class I CRISPR-Cas system architecture, and suggesting a function for type IV-B RNPs that may be distinct from other class 1 CRISPR-associated systems.
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Affiliation(s)
- Yi Zhou
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Jack P.K. Bravo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Hannah N. Taylor
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - Jurre A. Steens
- Laboratory of Microbiology, Wageningen University and Research, The Netherlands
| | - Ryan N. Jackson
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - Raymond H.J. Staals
- Laboratory of Microbiology, Wageningen University and Research, The Netherlands
| | - David W. Taylor
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX, USA
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, USA
- LIVESTRONG Cancer Institutes, Dell Medical School, Austin, TX, USA
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25
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León LM, Park AE, Borges AL, Zhang JY, Bondy-Denomy J. Mobile element warfare via CRISPR and anti-CRISPR in Pseudomonas aeruginosa. Nucleic Acids Res 2021; 49:2114-2125. [PMID: 33544853 PMCID: PMC7913775 DOI: 10.1093/nar/gkab006] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 12/27/2022] Open
Abstract
Bacteria deploy multiple defenses to prevent mobile genetic element (MGEs) invasion. CRISPR-Cas immune systems use RNA-guided nucleases to target MGEs, which counter with anti-CRISPR (Acr) proteins. Our understanding of the biology and co-evolutionary dynamics of the common Type I-C CRISPR-Cas subtype has lagged because it lacks an in vivo phage-host model system. Here, we show the anti-phage function of a Pseudomonas aeruginosa Type I-C CRISPR-Cas system encoded on a conjugative pKLC102 island, and its Acr-mediated inhibition by distinct MGEs. Seven genes with anti-Type I-C function (acrIC genes) were identified, many with highly acidic amino acid content, including previously described DNA mimic AcrIF2. Four of the acr genes were broad spectrum, also inhibiting I-E or I-F P. aeruginosa CRISPR-Cas subtypes. Dual inhibition comes at a cost, however, as simultaneous expression of Type I-C and I-F systems renders phages expressing the dual inhibitor AcrIF2 more sensitive to targeting. Mutagenesis of numerous acidic residues in AcrIF2 did not impair anti-I-C or anti-I-F function per se but did exacerbate inhibition defects during competition, suggesting that excess negative charge may buffer DNA mimics against competition. Like AcrIF2, five of the Acr proteins block Cascade from binding DNA, while two function downstream, likely preventing Cas3 recruitment or activity. One such inhibitor, AcrIC3, is found in an 'anti-Cas3' cluster within conjugative elements, encoded alongside bona fide Cas3 inhibitors AcrIF3 and AcrIE1. Our findings demonstrate an active battle between an MGE-encoded CRISPR-Cas system and its diverse MGE targets.
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Affiliation(s)
- Lina M León
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Allyson E Park
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Adair L Borges
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jenny Y Zhang
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94158, USA
- Innovative Genomics Institute, Berkeley, CA 94720, USA
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26
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McBride TM, Schwartz EA, Kumar A, Taylor DW, Fineran PC, Fagerlund RD. Diverse CRISPR-Cas Complexes Require Independent Translation of Small and Large Subunits from a Single Gene. Mol Cell 2020; 80:971-979.e7. [PMID: 33248026 DOI: 10.1016/j.molcel.2020.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/22/2020] [Accepted: 10/29/2020] [Indexed: 12/26/2022]
Abstract
CRISPR-Cas adaptive immune systems provide prokaryotes with defense against viruses by degradation of specific invading nucleic acids. Despite advances in the biotechnological exploitation of select systems, multiple CRISPR-Cas types remain uncharacterized. Here, we investigated the previously uncharacterized type I-D interference complex and revealed that it is a genetic and structural hybrid with similarity to both type I and type III systems. Surprisingly, formation of the functional complex required internal in-frame translation of small subunits from within the large subunit gene. We further show that internal translation to generate small subunits is widespread across diverse type I-D, I-B, and I-C systems, which account for roughly one quarter of CRISPR-Cas systems. Our work reveals the unexpected expansion of protein coding potential from within single cas genes, which has important implications for understanding CRISPR-Cas function and evolution.
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Affiliation(s)
- Tess M McBride
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Evan A Schwartz
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712-1597, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712-1597, USA
| | - Abhishek Kumar
- Centre for Protein Research, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - David W Taylor
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712-1597, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712-1597, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712-1597, USA; LIVESTRONG Cancer Institutes, Dell Medical School, Austin, TX 78712-1597, USA
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand; Bio-Protection Research Centre, University of Otago, PO Box 56, Dunedin 9054, New Zealand; Genetics Otago, University of Otago, Dunedin, New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand; Genetics Otago, University of Otago, Dunedin, New Zealand.
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27
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O'Brien RE, Santos IC, Wrapp D, Bravo JPK, Schwartz EA, Brodbelt JS, Taylor DW. Structural basis for assembly of non-canonical small subunits into type I-C Cascade. Nat Commun 2020; 11:5931. [PMID: 33230133 PMCID: PMC7684278 DOI: 10.1038/s41467-020-19785-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 10/30/2020] [Indexed: 01/07/2023] Open
Abstract
Bacteria and archaea employ CRISPR (clustered, regularly, interspaced, short palindromic repeats)-Cas (CRISPR-associated) systems as a type of adaptive immunity to target and degrade foreign nucleic acids. While a myriad of CRISPR-Cas systems have been identified to date, type I-C is one of the most commonly found subtypes in nature. Interestingly, the type I-C system employs a minimal Cascade effector complex, which encodes only three unique subunits in its operon. Here, we present a 3.1 Å resolution cryo-EM structure of the Desulfovibrio vulgaris type I-C Cascade, revealing the molecular mechanisms that underlie RNA-directed complex assembly. We demonstrate how this minimal Cascade utilizes previously overlooked, non-canonical small subunits to stabilize R-loop formation. Furthermore, we describe putative PAM and Cas3 binding sites. These findings provide the structural basis for harnessing the type I-C Cascade as a genome-engineering tool.
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Affiliation(s)
- Roisin E O'Brien
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Inês C Santos
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Daniel Wrapp
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Jack P K Bravo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Evan A Schwartz
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - David W Taylor
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA.
- 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.
- Livestrong Cancer Institutes, Dell Medical School, Austin, TX, 78712, USA.
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28
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Abstract
Genome editing in plants has advanced greatly by applying the clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas system, especially CRISPR-Cas9. However, CRISPR type I—the most abundant CRISPR system in bacteria—has not been exploited for plant genome modification. In type I CRISPR-Cas systems, e.g., type I-E, Cas3 nucleases degrade the target DNA in mammals. Here, we present a type I-D (TiD) CRISPR-Cas genome editing system in plants. TiD lacks the Cas3 nuclease domain; instead, Cas10d is the functional nuclease in vivo. TiD was active in targeted mutagenesis of tomato genomic DNA. The mutations generated by TiD differed from those of CRISPR/Cas9; both bi-directional long-range deletions and short indels mutations were detected in tomato cells. Furthermore, TiD can be used to efficiently generate bi-allelic mutant plants in the first generation. These findings indicate that TiD is a unique CRISPR system that can be used for genome engineering in plants. Osakabe et al. report the implementation of a CRISPR type I-D (TiD) system for editing in plants, which consists of eight Cas genes (Cas1d–Cas7d, Cas10d) followed by an array of repeat spacer units. The CRISPR TiD can effectively induce short indels, long-range deletions and bi-allelic mutations in plants, adding a valuable toolbox to manipulate plant genomes.
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29
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Csörgő B, León LM, Chau-Ly IJ, Vasquez-Rifo A, Berry JD, Mahendra C, Crawford ED, Lewis JD, Bondy-Denomy J. A compact Cascade–Cas3 system for targeted genome engineering. Nat Methods 2020; 17:1183-1190. [DOI: 10.1038/s41592-020-00980-w] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 09/15/2020] [Indexed: 12/26/2022]
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30
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Genetic Dissection of the Type III-A CRISPR-Cas System Csm Complex Reveals Roles of Individual Subunits. Cell Rep 2020; 26:2753-2765.e4. [PMID: 30840895 DOI: 10.1016/j.celrep.2019.02.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/29/2018] [Accepted: 02/07/2019] [Indexed: 12/26/2022] Open
Abstract
The type III-A Csm complex of Streptococcus thermophilus (StCsm) provides immunity against invading nucleic acids through the coordinated action of three catalytic domains: RNase (Csm3), ssDNase (Cas10-HD), and cyclic oligoadenylates synthase (Cas10-Palm). The matured StCsm complex is composed of Cas10:Csm2:Csm3:Csm4:Csm5 subunits and 40-nt CRISPR RNA (crRNA). We have carried out gene disruptions for each subunit and isolated deletion complexes to reveal the role of individual subunits in complex assembly and function. We show that the Cas10-Csm4 subcomplex binds the 5'-handle of crRNA and triggers Csm3 oligomerization to form a padlock for crRNA binding. We demonstrate that Csm5 plays a key role in target RNA binding while Csm2 ensures RNA cleavage at multiple sites by Csm3. Finally, guided by deletion analysis, we engineered a minimal Csm complex containing only the Csm3, Csm4, and Cas10 subunits and crRNA and demonstrated that it retains all three catalytic activities, thus paving the way for practical applications.
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31
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Nimkar S, Anand B. Cas3/I-C mediated target DNA recognition and cleavage during CRISPR interference are independent of the composition and architecture of Cascade surveillance complex. Nucleic Acids Res 2020; 48:2486-2501. [PMID: 31980818 PMCID: PMC7049708 DOI: 10.1093/nar/gkz1218] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 12/17/2019] [Accepted: 01/22/2020] [Indexed: 12/26/2022] Open
Abstract
In type I CRISPR-Cas system, Cas3—a nuclease cum helicase—in cooperation with Cascade surveillance complex cleaves the target DNA. Unlike the Cascade/I-E, which is composed of five subunits, the Cascade/I-C is made of only three subunits lacking the CRISPR RNA processing enzyme Cas6, whose role is assumed by Cas5. How these differences in the composition and organization of Cascade subunits in type I-C influence the Cas3/I-C binding and its target cleavage mechanism is poorly understood. Here, we show that Cas3/I-C is intrinsically a single-strand specific promiscuous nuclease. Apart from the helicase domain, a constellation of highly conserved residues—which are unique to type I-C—located in the uncharacterized C-terminal domain appears to influence the nuclease activity. Recruited by Cascade/I-C, the HD nuclease of Cas3/I-C nicks the single-stranded region of the non-target strand and positions the helicase motor. Powered by ATP, the helicase motor reels in the target DNA, until it encounters the roadblock en route, which stimulates the HD nuclease. Remarkably, we show that Cas3/I-C supplants Cas3/I-E for CRISPR interference in type I-E in vivo, suggesting that the target cleavage mechanism is evolutionarily conserved between type I-C and type I-E despite the architectural difference exhibited by Cascade/I-C and Cascade/I-E.
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Affiliation(s)
- Siddharth Nimkar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - B Anand
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
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32
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Novel molecular aspects of the CRISPR backbone protein ‘Cas7’ from cyanobacteria. Biochem J 2020; 477:971-983. [DOI: 10.1042/bcj20200026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/11/2020] [Accepted: 02/13/2020] [Indexed: 01/16/2023]
Abstract
The cyanobacterium Anabaena PCC 7120 shows the presence of Type I-D CRISPR system that can potentially confer adaptive immunity. The Cas7 protein (Alr1562), which forms the backbone of the type I-D surveillance complex, was characterized from Anabaena. Alr1562, showed the presence of the non-canonical RNA recognition motif and two intrinsically disordered regions (IDRs). When overexpressed in E. coli, the Alr1562 protein was soluble and could be purified by affinity chromatography, however, deletion of IDRs rendered Alr1562 completely insoluble. The purified Alr1562 was present in the dimeric or a RNA-associated higher oligomeric form, which appeared as spiral structures under electron microscope. With RNaseA and NaCl treatment, the higher oligomeric form converted to the lower oligomeric form, indicating that oligomerization occurred due to the association of Alr1562 with RNA. The secondary structure of both these forms was largely similar, resembling that of a partially folded protein. The dimeric Alr1562 was more prone to temperature-dependent aggregation than the higher oligomeric form. In vitro, the Alr1562 bound more specifically to a minimal CRISPR unit than to the non-specific RNA. Residues required for binding of Alr1562 to RNA, identified by protein modeling-based approaches, were mutated for functional validation. Interestingly, these mutant proteins, showing reduced ability to bind RNA were predominantly present in dimeric form. Alr1562 was detected with specific antiserum in Anabaena, suggesting that the type I-D system is expressed and may be functional in vivo. This is the first report that describes the characterization of a Cas protein from any photosynthetic organism.
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33
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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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34
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Pickar-Oliver A, Black JB, Lewis MM, Mutchnick KJ, Klann TS, Gilcrest KA, Sitton MJ, Nelson CE, Barrera A, Bartelt LC, Reddy TE, Beisel CL, Barrangou R, Gersbach CA. Targeted transcriptional modulation with type I CRISPR-Cas systems in human cells. Nat Biotechnol 2019; 37:1493-1501. [PMID: 31548729 PMCID: PMC6893126 DOI: 10.1038/s41587-019-0235-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/23/2019] [Indexed: 12/19/2022]
Abstract
Class 2 CRISPR-Cas systems, such as Cas9 and Cas12, have been widely used to target DNA sequences in eukaryotic genomes. However, class 1 CRISPR-Cas systems, which represent about 90% of all CRISPR systems in nature, remain largely unexplored for genome engineering applications. Here, we show that class 1 CRISPR-Cas systems can be expressed in mammalian cells and used for DNA targeting and transcriptional control. We repurpose type I variants of class 1 CRISPR-Cas systems from Escherichia coli and Listeria monocytogenes, which target DNA via a multi-component RNA-guided complex termed Cascade. We validate Cascade expression, complex formation and nuclear localization in human cells, and demonstrate programmable CRISPR RNA (crRNA)-mediated targeting of specific loci in the human genome. By tethering activation and repression domains to Cascade, we modulate the expression of targeted endogenous genes in human cells. This study demonstrates the use of Cascade as a CRISPR-based technology for targeted eukaryotic gene regulation, highlighting class 1 CRISPR-Cas systems for further exploration.
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Affiliation(s)
- Adrian Pickar-Oliver
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Joshua B Black
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Mae M Lewis
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Kevin J Mutchnick
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Tyler S Klann
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Kylie A Gilcrest
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Madeleine J Sitton
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Christopher E Nelson
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
| | - Alejandro Barrera
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA
| | - Luke C Bartelt
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA
| | - Timothy E Reddy
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, NC, USA
- University Program in Genetics and Genomics, Duke University, Durham, NC, USA
| | - Chase L Beisel
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz-Centre for Infection Research (HZI), Würzburg, Germany
- Medical Faculty, University of Würzburg, Würzburg, Germany
| | - Rodolphe Barrangou
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Charles A Gersbach
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, USA.
- Department of Surgery, Duke University Medical Center, Durham, NC, USA.
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35
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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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36
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Soto-Perez P, Bisanz JE, Berry JD, Lam KN, Bondy-Denomy J, Turnbaugh PJ. CRISPR-Cas System of a Prevalent Human Gut Bacterium Reveals Hyper-targeting against Phages in a Human Virome Catalog. Cell Host Microbe 2019; 26:325-335.e5. [PMID: 31492655 DOI: 10.1016/j.chom.2019.08.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/20/2019] [Accepted: 08/13/2019] [Indexed: 12/26/2022]
Abstract
Bacteriophages are abundant within the human gastrointestinal tract, yet their interactions with gut bacteria remain poorly understood, particularly with respect to CRISPR-Cas immunity. Here, we show that the type I-C CRISPR-Cas system in the prevalent gut Actinobacterium Eggerthella lenta is transcribed and sufficient for specific targeting of foreign and chromosomal DNA. Comparative analyses of E. lenta CRISPR-Cas systems across (meta)genomes revealed 2 distinct clades according to cas sequence similarity and spacer content. We assembled a human virome database (HuVirDB), encompassing 1,831 samples enriched for viral DNA, to identify protospacers. This revealed matches for a majority of spacers, a marked increase over other databases, and uncovered "hyper-targeted" phage sequences containing multiple protospacers targeted by several E. lenta strains. Finally, we determined the positional mismatch tolerance of observed spacer-protospacer pairs. This work emphasizes the utility of merging computational and experimental approaches for determining the function and targets of CRISPR-Cas systems.
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Affiliation(s)
- Paola Soto-Perez
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Jordan E Bisanz
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Joel D Berry
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Kathy N Lam
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Peter J Turnbaugh
- Department of Microbiology & Immunology, University of California, San Francisco, San Francisco, CA 94143, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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37
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Rollins MF, Chowdhury S, Carter J, Golden SM, Miettinen HM, Santiago-Frangos A, Faith D, Lawrence CM, Lander GC, Wiedenheft B. Structure Reveals a Mechanism of CRISPR-RNA-Guided Nuclease Recruitment and Anti-CRISPR Viral Mimicry. Mol Cell 2019; 74:132-142.e5. [PMID: 30872121 PMCID: PMC6521718 DOI: 10.1016/j.molcel.2019.02.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/21/2018] [Accepted: 01/30/2019] [Indexed: 12/14/2022]
Abstract
Bacteria and archaea have evolved sophisticated adaptive immune systems that rely on CRISPR RNA (crRNA)-guided detection and nuclease-mediated elimination of invading nucleic acids. Here, we present the cryo-electron microscopy (cryo-EM) structure of the type I-F crRNA-guided surveillance complex (Csy complex) from Pseudomonas aeruginosa bound to a double-stranded DNA target. Comparison of this structure to previously determined structures of this complex reveals a ∼180-degree rotation of the C-terminal helical bundle on the "large" Cas8f subunit. We show that the double-stranded DNA (dsDNA)-induced conformational change in Cas8f exposes a Cas2/3 "nuclease recruitment helix" that is structurally homologous to a virally encoded anti-CRISPR protein (AcrIF3). Structural homology between Cas8f and AcrIF3 suggests that AcrIF3 is a mimic of the Cas8f nuclease recruitment helix.
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MESH Headings
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Bacterial Proteins/metabolism
- CRISPR-Associated Proteins/chemistry
- CRISPR-Associated Proteins/genetics
- CRISPR-Associated Proteins/immunology
- CRISPR-Associated Proteins/metabolism
- CRISPR-Cas Systems
- Clustered Regularly Interspaced Short Palindromic Repeats
- Cryoelectron Microscopy
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Models, Molecular
- Molecular Mimicry
- Nucleic Acid Conformation
- Protein Conformation
- Pseudomonas aeruginosa/enzymology
- Pseudomonas aeruginosa/genetics
- Pseudomonas aeruginosa/immunology
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/chemistry
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
- Structure-Activity Relationship
- Viral Proteins/chemistry
- Viral Proteins/genetics
- Viral Proteins/immunology
- Viral Proteins/metabolism
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Affiliation(s)
- MaryClare F Rollins
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Saikat Chowdhury
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, USA
| | - Joshua Carter
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Sarah M Golden
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Heini M Miettinen
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | | | - Dominick Faith
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - C Martin Lawrence
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, CA, USA.
| | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.
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38
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Abstract
The discovery and characterization of the prokaryotic CRISPR-Cas immune system has led to a revolution in genome editing and engineering technologies. Despite the fact that most applications emerged after the discovery of the type II-A CRISPR-Cas9 system of Streptococcus pyogenes, its biological importance in this organism has received little attention. Here, we provide a comprehensive overview of the current knowledge about CRISPR-Cas systems from S. pyogenes. We discuss how the interplay between CRISPR-mediated immunity and horizontal gene transfer might have modeled the evolution of this pathogen. We review the current literature about the CRISPR-Cas systems present in S. pyogenes (types I-C and II-A), and describe their distinctive biochemical and functional features. Finally, we summarize the main biotechnological applications that have arisen from the discovery of the CRISPR-Cas9 system in S. pyogenes.
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Affiliation(s)
- Anaïs Le Rhun
- a Max Planck Unit for the Science of Pathogens , Berlin , Germany
| | - Andrés Escalera-Maurer
- a Max Planck Unit for the Science of Pathogens , Berlin , Germany.,b Institute for Biology , Humboldt University , Berlin , Germany
| | - Majda Bratovič
- a Max Planck Unit for the Science of Pathogens , Berlin , Germany.,b Institute for Biology , Humboldt University , Berlin , Germany
| | - Emmanuelle Charpentier
- a Max Planck Unit for the Science of Pathogens , Berlin , Germany.,b Institute for Biology , Humboldt University , Berlin , Germany
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39
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Crystal Structures of Csm2 and Csm3 in the Type III-A CRISPR–Cas Effector Complex. J Mol Biol 2019; 431:748-763. [DOI: 10.1016/j.jmb.2019.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 12/22/2018] [Accepted: 01/05/2019] [Indexed: 12/26/2022]
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40
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Özcan A, Pausch P, Linden A, Wulf A, Schühle K, Heider J, Urlaub H, Heimerl T, Bange G, Randau L. Type IV CRISPR RNA processing and effector complex formation in Aromatoleum aromaticum. Nat Microbiol 2019; 4:89-96. [PMID: 30397343 DOI: 10.1038/s41564-018-0274-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/24/2018] [Indexed: 12/24/2022]
Abstract
Type IV CRISPR-Cas modules belong to class 1 prokaryotic adaptive immune systems, which are defined by the presence of multisubunit effector complexes. They usually lack the known Cas proteins involved in adaptation and target cleavage, and their function has not been experimentally addressed. To investigate RNA and protein components of this CRISPR-Cas type, we located a complete type IV cas gene locus and an adjacent CRISPR array on a megaplasmid of Aromatoleum aromaticum EbN1, which contains an additional type I-C system on its chromosome. RNA sequencing analyses verified CRISPR RNA (crRNA) production and maturation for both systems. Type IV crRNAs were shown to harbour unusually short 7 nucleotide 5'-repeat tags and stable 3' hairpin structures. A unique Cas6 variant (Csf5) was identified that generates crRNAs that are specifically incorporated into type IV CRISPR-ribonucleoprotein (crRNP) complexes. Structures of RNA-bound Csf5 were obtained. Recombinant production and purification of the type IV Cas proteins, together with electron microscopy, revealed that Csf2 acts as a helical backbone for type IV crRNPs that include Csf5, Csf3 and a large subunit (Csf1). Mass spectrometry analyses identified protein-protein and protein-RNA contact sites. These results highlight evolutionary connections between type IV and type I CRISPR-Cas systems and demonstrate that type IV CRISPR-Cas systems employ crRNA-guided effector complexes.
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Affiliation(s)
- Ahsen Özcan
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Patrick Pausch
- LOEWE Center for Synthetic Microbiology (Synmikro), Philipps University Marburg, Marburg, Germany
- Faculty of Chemistry, Philipps-University-Marburg, Marburg, Germany
| | - Andreas Linden
- Bioanalytics Research Group, Department of Clinical Chemistry, University Medical Centre, Göttingen, Germany
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Alexander Wulf
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Karola Schühle
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Johann Heider
- LOEWE Center for Synthetic Microbiology (Synmikro), Philipps University Marburg, Marburg, Germany
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Henning Urlaub
- Bioanalytics Research Group, Department of Clinical Chemistry, University Medical Centre, Göttingen, Germany
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Thomas Heimerl
- LOEWE Center for Synthetic Microbiology (Synmikro), Philipps University Marburg, Marburg, Germany
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology (Synmikro), Philipps University Marburg, Marburg, Germany
- Faculty of Chemistry, Philipps-University-Marburg, Marburg, Germany
| | - Lennart Randau
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
- LOEWE Center for Synthetic Microbiology (Synmikro), Philipps University Marburg, Marburg, Germany.
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41
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Majumdar S, Terns MP. CRISPR RNA-guided DNA cleavage by reconstituted Type I-A immune effector complexes. Extremophiles 2018; 23:19-33. [PMID: 30284045 DOI: 10.1007/s00792-018-1057-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 09/24/2018] [Indexed: 12/16/2022]
Abstract
Diverse CRISPR-Cas immune systems protect archaea and bacteria from viruses and other mobile genetic elements. All CRISPR-Cas systems ultimately function by sequence-specific destruction of invading complementary nucleic acids. However, each CRISPR system uses compositionally distinct crRNP [CRISPR (cr) RNA/Cas protein] immune effector complexes to recognize and destroy invasive nucleic acids by unique molecular mechanisms. Previously, we found that Type I-A (Csa) effector crRNPs from Pyrococcus furiosus function in vivo to eliminate invader DNA. Here, we reconstituted functional Type I-A effector crRNPs in vitro with recombinant Csa proteins and synthetic crRNA and characterized properties of crRNP assembly, target DNA recognition and cleavage. Six proteins (Csa 4-1, Cas3″, Cas3', Cas5a, Csa2, Csa5) are essential for selective target DNA binding and cleavage. Native gel shift analysis and UV-induced RNA-protein crosslinking demonstrate that Cas5a and Csa2 directly interact with crRNA 5' tag and guide sequences, respectively. Mutational analysis revealed that Cas3″ is the effector nuclease of the complex. Together, our results indicate that DNA cleavage by Type I-A crRNPs requires crRNA-guided and protospacer adjacent motif-dependent target DNA binding to unwind double-stranded DNA and expose single strands for progressive ATP-dependent 3'-5' cleavage catalyzed by integral Cas3' helicase and Cas3″ nuclease crRNP components.
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Affiliation(s)
- Sonali Majumdar
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Michael P Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA. .,Department of Genetics, University of Georgia, Athens, GA, 30602, USA. .,Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.
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42
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Makarova KS, Wolf YI, Koonin EV. Classification and Nomenclature of CRISPR-Cas Systems: Where from Here? CRISPR J 2018; 1:325-336. [PMID: 31021272 DOI: 10.1089/crispr.2018.0033] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As befits an immune mechanism, CRISPR-Cas systems are highly variable with respect to Cas protein sequences, gene composition, and organization of the genomic loci. Optimal classification of CRISPR-Cas systems and rational nomenclature for CRISPR-associated genes are essential for further progress of CRISPR research. These are highly challenging tasks because of the complexity of CRISPR-Cas and their fast evolution, including frequent module shuffling, as well as the lack of universal markers for a consistent evolutionary classification. The complexity and variability of CRISPR-Cas systems necessitate a multipronged approach to classification and nomenclature. We present a brief summary of the current state of the art and discuss further directions in this area.
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Affiliation(s)
- Kira S Makarova
- National Center for Biotechnology Information , National Library of Medicine, Bethesda, Maryland
| | - Yuri I Wolf
- National Center for Biotechnology Information , National Library of Medicine, Bethesda, Maryland
| | - Eugene V Koonin
- National Center for Biotechnology Information , National Library of Medicine, Bethesda, Maryland
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43
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The advances in CRISPR technology and 3D genome. Semin Cell Dev Biol 2018; 90:54-61. [PMID: 30004018 DOI: 10.1016/j.semcdb.2018.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 07/08/2018] [Indexed: 12/26/2022]
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) system is a prokaryotic immune system that used to resist foreign genetic factors. It rapidly becomes the hot technology in life sciences and is applies for genome editing to solve the problem of genome-derived diseases. Using CRISPR/Cas technique, the biological DNA sequence can be repaired, cut, replaced, or added. It can effectively change the human stem cells and is expected to achieve results in the treatment. Compared with ZFN and TALEN genome editing techniques, CRISPR is more effective, accurate, and convenient. The application of CRISPR technique in three dimensional (3D) genome structure makes us understand the relationship between linear DNA sequence and 3D chromatin structure. Utilizing CRISPR/Cas9 genome editing to reverse or delete CTCF binding sites, to recognize changes of topological isomerism of the genome and interactions between chromatin loops. The purpose of this review is to introduce the characteristics and classification of the current CRISPR/Cas system, multiple functions, and potential therapeutic uses, as well as to outline the effect of the technique on chromatin loops by changing CTCF sites in 3D genomes. We will also briefly describe the importance of ethical dilemmas to be faced in CRISPR applications and provide a perspective for potential CRISPR considerations.
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44
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Abstract
CRISPR-Cas systems are a highly effective immune mechanism for prokaryotes, providing defense against invading foreign DNA. By definition, all CRISPR-Cas systems have short repeats interspersing their spacers. These repeats play a key role in preventing cleavage of self DNA and in the integration of new spacers. Here we focus on the phenomenon of repeat modularity, namely the unexpectedly high degree of repeat conservation across different systems within a genome or between different species. We hypothesize that modularity can be beneficial for CRISPR-Cas containing organisms, because it facilitates horizontal acquisition of 'pre-immunized' CRISPR arrays and allows the utilization of spacers acquired by one system for use by other systems within the same cell.
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Affiliation(s)
- Yael Yair
- a School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences , Tel Aviv University , Tel Aviv , Israel
| | - Uri Gophna
- a School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences , Tel Aviv University , Tel Aviv , Israel
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45
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Maikova A, Severinov K, Soutourina O. New Insights Into Functions and Possible Applications of Clostridium difficile CRISPR-Cas System. Front Microbiol 2018; 9:1740. [PMID: 30108577 PMCID: PMC6079278 DOI: 10.3389/fmicb.2018.01740] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/12/2018] [Indexed: 12/26/2022] Open
Abstract
Over the last decades the enteric bacterium Clostridium difficile (novel name Clostridioides difficile) - has emerged as an important human nosocomial pathogen. It is a leading cause of hospital-acquired diarrhea and represents a major challenge for healthcare providers. Many aspects of C. difficile pathogenesis and its evolution remain poorly understood. Efficient defense systems against phages and other genetic elements could have contributed to the success of this enteropathogen in the phage-rich gut communities. Recent studies demonstrated the presence of an active CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) subtype I-B system in C. difficile. In this mini-review, we will discuss the recent advances in characterization of original features of the C. difficile CRISPR-Cas system in laboratory and clinical strains, as well as interesting perspectives for our understanding of this defense system function and regulation in this important enteropathogen. This knowledge will pave the way for the development of promising biotechnological and therapeutic tools in the future. Possible applications for the C. difficile strain monitoring and genotyping, as well as for CRISPR-based genome editing and antimicrobials are also discussed.
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Affiliation(s)
- Anna Maikova
- Center for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France.,Microbiology, Institute for Integrative Biology of the Cell, Commissariat à l'Energie Atomique et aux Energies Alternatives, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.,Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Russia
| | - Konstantin Severinov
- Center for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, Russia.,Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, Russia.,Waksman Institute for Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ, United States
| | - Olga Soutourina
- Microbiology, Institute for Integrative Biology of the Cell, Commissariat à l'Energie Atomique et aux Energies Alternatives, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.,Institut Pasteur, Paris, France
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46
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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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47
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Systematic prediction of genes functionally linked to CRISPR-Cas systems by gene neighborhood analysis. Proc Natl Acad Sci U S A 2018; 115:E5307-E5316. [PMID: 29784811 DOI: 10.1073/pnas.1803440115] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The CRISPR-Cas systems of bacterial and archaeal adaptive immunity consist of direct repeat arrays separated by unique spacers and multiple CRISPR-associated (cas) genes encoding proteins that mediate all stages of the CRISPR response. In addition to the relatively small set of core cas genes that are typically present in all CRISPR-Cas systems of a given (sub)type and are essential for the defense function, numerous genes occur in CRISPR-cas loci only sporadically. Some of these have been shown to perform various ancillary roles in CRISPR response, but the functional relevance of most remains unknown. We developed a computational strategy for systematically detecting genes that are likely to be functionally linked to CRISPR-Cas. The approach is based on a "CRISPRicity" metric that measures the strength of CRISPR association for all protein-coding genes from sequenced bacterial and archaeal genomes. Uncharacterized genes with CRISPRicity values comparable to those of cas genes are considered candidate CRISPR-linked genes. We describe additional criteria to predict functionally relevance for genes in the candidate set and identify 79 genes as strong candidates for functional association with CRISPR-Cas systems. A substantial majority of these CRISPR-linked genes reside in type III CRISPR-cas loci, which implies exceptional functional versatility of type III systems. Numerous candidate CRISPR-linked genes encode integral membrane proteins suggestive of tight membrane association of CRISPR-Cas systems, whereas many others encode proteins implicated in various signal transduction pathways. These predictions provide ample material for improving annotation of CRISPR-cas loci and experimental characterization of previously unsuspected aspects of CRISPR-Cas system functionality.
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48
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Earl LA, Falconieri V, Subramaniam S. Microbiology catches the cryo-EM bug. Curr Opin Microbiol 2018; 43:199-207. [PMID: 29656089 DOI: 10.1016/j.mib.2018.02.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 02/27/2018] [Indexed: 11/18/2022]
Abstract
Over the past few years, the advances in technology and methods that have revolutionized cryo-EM are allowing for key insights in a variety of areas in biology, and microbiology is no exception. A wide range of important macromolecular assemblies in prokaryotic and eukaryotic cells, as well as intact viruses, have now become accessible to investigation by new methods in 3D electron microscopy. We focus here on selected examples that illustrate this breadth, and review the application of methods in single particle cryo-EM and cryo-electron tomography to progress in the structural biology of CRISPR systems, visualization of small molecule drugs in membrane proteins, in situ visualization of bacterial nanomachines, and the analysis of antigen-antibody interactions to drive vaccine design.
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Affiliation(s)
- Lesley A Earl
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Veronica Falconieri
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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49
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Hille F, Richter H, Wong SP, Bratovič M, Ressel S, Charpentier E. The Biology of CRISPR-Cas: Backward and Forward. Cell 2018. [DOI: 10.1016/j.cell.2017.11.032] [Citation(s) in RCA: 333] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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50
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Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) RNAs in the Porphyromonas gingivalis CRISPR-Cas I-C System. J Bacteriol 2017; 199:JB.00275-17. [PMID: 28893837 DOI: 10.1128/jb.00275-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 08/25/2017] [Indexed: 11/20/2022] Open
Abstract
The CRISPR-Cas (clustered regularly interspaced short palindromic repeat-CRISPR-associated protein) system is unique to prokaryotes and provides the majority of bacteria and archaea with immunity against nucleic acids of foreign origin. CRISPR RNAs (crRNAs) are the key element of this system, since they are responsible for its selectivity and effectiveness. Typical crRNAs consist of a spacer sequence flanked with 5' and 3' handles originating from repeat sequences that are important for recognition of these small RNAs by the Cas machinery. In this investigation, we studied the type I-C CRISPR-Cas system in Porphyromonas gingivalis, a human pathogen associated with periodontitis, rheumatoid arthritis, cardiovascular disease, and aspiration pneumonia. We demonstrated the importance of the 5' handle for crRNA recognition by the effector complex and consequently activity, as well as secondary trimming of the 3' handle, which was not affected by modifications of the repeat sequence.IMPORTANCEPorphyromonas gingivalis, a clinically relevant Gram-negative, anaerobic bacterium, is one of the major etiologic agents of periodontitis and has been linked with the development of other clinical conditions, including rheumatoid arthritis, cardiovascular disease, and aspiration pneumonia. The presented results on the biogenesis and functions of crRNAs expand our understanding of CRISPR-Cas cellular defenses in P. gingivalis and of horizontal gene transfer in bacteria.
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