1
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Schwartz EA, Bravo JPK, Ahsan M, Macias LA, McCafferty CL, Dangerfield TL, Walker JN, Brodbelt JS, Palermo G, Fineran PC, Fagerlund RD, Taylor DW. RNA targeting and cleavage by the type III-Dv CRISPR effector complex. Nat Commun 2024; 15:3324. [PMID: 38637512 PMCID: PMC11026444 DOI: 10.1038/s41467-024-47506-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 04/02/2024] [Indexed: 04/20/2024] Open
Abstract
CRISPR-Cas are adaptive immune systems in bacteria and archaea that utilize CRISPR RNA-guided surveillance complexes to target complementary RNA or DNA for destruction1-5. Target RNA cleavage at regular intervals is characteristic of type III effector complexes6-8. Here, we determine the structures of the Synechocystis type III-Dv complex, an apparent evolutionary intermediate from multi-protein to single-protein type III effectors9,10, in pre- and post-cleavage states. The structures show how multi-subunit fusion proteins in the effector are tethered together in an unusual arrangement to assemble into an active and programmable RNA endonuclease and how the effector utilizes a distinct mechanism for target RNA seeding from other type III effectors. Using structural, biochemical, and quantum/classical molecular dynamics simulation, we study the structure and dynamics of the three catalytic sites, where a 2'-OH of the ribose on the target RNA acts as a nucleophile for in line self-cleavage of the upstream scissile phosphate. Strikingly, the arrangement at the catalytic residues of most type III complexes resembles the active site of ribozymes, including the hammerhead, pistol, and Varkud satellite ribozymes. Our work provides detailed molecular insight into the mechanisms of RNA targeting and cleavage by an important intermediate in the evolution of type III effector complexes.
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Affiliation(s)
- Evan A Schwartz
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX, USA
| | - Jack P K Bravo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Mohd Ahsan
- Department of Bioengineering and Department of Chemistry, University of California, Riverside, CA, USA
| | - Luis A Macias
- Department of Chemistry, University of Texas at Austin, Austin, TX, USA
| | - Caitlyn L McCafferty
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX, USA
| | - Tyler L Dangerfield
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Jada N Walker
- Department of Chemistry, University of Texas at Austin, Austin, TX, USA
| | | | - Giulia Palermo
- Department of Bioengineering and Department of Chemistry, University of California, Riverside, CA, USA.
| | - Peter C Fineran
- Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin, New Zealand
| | - Robert D Fagerlund
- Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, New Zealand.
- Bioprotection Aotearoa, University of Otago, PO Box 56, Dunedin, New Zealand.
- Genetics Otago, University of Otago, PO Box 56, Dunedin, New Zealand.
| | - David W Taylor
- Interdisciplinary Life Sciences Graduate Programs, University of Texas at Austin, Austin, TX, USA.
- Department of Molecular Biosciences, 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, University of Texas at Austin, Austin, TX, USA.
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2
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Ganguly C, Rostami S, Long K, Aribam SD, Rajan R. Unity among the diverse RNA-guided CRISPR-Cas interference mechanisms. J Biol Chem 2024:107295. [PMID: 38641067 DOI: 10.1016/j.jbc.2024.107295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 04/08/2024] [Accepted: 04/10/2024] [Indexed: 04/21/2024] Open
Abstract
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems are adaptive immune systems that protect bacteria and archaea from invading mobile genetic elements (MGEs). The Cas protein-CRISPR RNA (crRNA) complex uses complementarity of the crRNA "guide" region to specifically recognize the invader genome. CRISPR effectors that perform targeted destruction of the foreign genome have emerged independently as multi-subunit protein complexes (Class 1 systems) and as single multi-domain proteins (Class 2). These different CRISPR-Cas systems can cleave RNA, DNA, and protein in an RNA-guided manner to eliminate the invader, and in some cases, they initiate programmed cell death/dormancy. The versatile mechanisms of the different CRISPR-Cas systems to target and destroy nucleic acids have been adapted to develop various programmable-RNA-guided tools and have revolutionized the development of fast, accurate, and accessible genomic applications. In this review, we present the structure and interference mechanisms of different CRISPR-Cas systems and an analysis of their unified features. The three types of Class 1 systems (I, III, and IV) have a conserved right-handed helical filamentous structure that provides a backbone for sequence-specific targeting while using unique proteins with distinct mechanisms to destroy the invader. Similarly, all three Class 2 types (II, V, and VI) have a bilobed architecture that binds the RNA-DNA/RNA hybrid and uses different nuclease domains to cleave invading MGEs. Additionally, we highlight the mechanistic similarities of CRISPR-Cas enzymes with other RNA cleaving enzymes and briefly present the evolutionary routes of the different CRISPR-Cas systems.
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Affiliation(s)
- Chhandosee Ganguly
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA
| | - Saadi Rostami
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA
| | - Kole Long
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA
| | - Swarmistha Devi Aribam
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, OK, 73019, USA.
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3
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Han X, Chang L, Chen H, Zhao J, Tian F, Ross RP, Stanton C, van Sinderen D, Chen W, Yang B. Harnessing the endogenous Type I-C CRISPR-Cas system for genome editing in Bifidobacterium breve. Appl Environ Microbiol 2024; 90:e0207423. [PMID: 38319094 PMCID: PMC10952402 DOI: 10.1128/aem.02074-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/14/2024] [Indexed: 02/07/2024] Open
Abstract
Bifidobacterium breve, one of the main bifidobacterial species colonizing the human gastrointestinal tract in early life, has received extensive attention for its purported beneficial effects on human health. However, exploration of the mode of action of such beneficial effects exerted by B. breve is cumbersome due to the lack of effective genetic tools, which limits its synthetic biology application. The widespread presence of CRISPR-Cas systems in the B. breve genome makes endogenous CRISPR-based gene editing toolkits a promising tool. This study revealed that Type I-C CRISPR-Cas systems in B. breve can be divided into two groups based on the amino acid sequences encoded by cas gene clusters. Deletion of the gene coding uracil phosphoribosyl-transferase (upp) was achieved in five B. breve strains from both groups using this system. In addition, translational termination of uracil phosphoribosyl-transferase was successfully achieved in B. breve FJSWX38M7 by single-base substitution of the upp gene and insertion of three stop codons. The gene encoding linoleic acid isomerase (bbi) in B. breve, being a characteristic trait, was deleted after plasmid curing, which rendered it unable to convert linoleic acid into conjugated linoleic acid, demonstrating the feasibility of successive editing. This study expands the toolkit for gene manipulation in B. breve and provides a new approach toward functional genome editing and analysis of B. breve strains.IMPORTANCEThe lack of effective genetic tools for Bifidobacterium breve is an obstacle to studying the molecular mechanisms of its health-promoting effects, hindering the development of next-generation probiotics. Here, we introduce a gene editing method based on the endogenous CRISPR-Cas system, which can achieve gene deletion, single-base substitution, gene insertion, and successive gene editing in B. breve. This study will facilitate discovery of functional genes and elucidation of molecular mechanisms of B. breve pertaining to health-associated benefits.
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Affiliation(s)
- Xiao Han
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Lulu Chang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Haiqin Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Jianxin Zhao
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Fengwei Tian
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
- International Joint Research Center for Probiotics & Gut Health, Jiangnan University, Wuxi, Jiangsu, China
| | - R. Paul Ross
- International Joint Research Center for Probiotics & Gut Health, Jiangnan University, Wuxi, Jiangsu, China
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Catherine Stanton
- International Joint Research Center for Probiotics & Gut Health, Jiangnan University, Wuxi, Jiangsu, China
- Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
| | | | - Wei Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
- National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, Jiangsu, China
| | - Bo Yang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
- International Joint Research Center for Probiotics & Gut Health, Jiangnan University, Wuxi, Jiangsu, China
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4
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Wang S, Gabel C, Siddique R, Klose T, Chang L. Molecular mechanism for Tn7-like transposon recruitment by a type I-B CRISPR effector. Cell 2023; 186:4204-4215.e19. [PMID: 37557170 PMCID: PMC11027886 DOI: 10.1016/j.cell.2023.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/23/2023] [Accepted: 07/10/2023] [Indexed: 08/11/2023]
Abstract
Tn7-like transposons have co-opted CRISPR-Cas systems to facilitate the movement of their own DNA. These CRISPR-associated transposons (CASTs) are promising tools for programmable gene knockin. A key feature of CASTs is their ability to recruit Tn7-like transposons to nuclease-deficient CRISPR effectors. However, how Tn7-like transposons are recruited by diverse CRISPR effectors remains poorly understood. Here, we present the cryo-EM structure of a recruitment complex comprising the Cascade complex, TniQ, TnsC, and the target DNA in the type I-B CAST from Peltigera membranacea cyanobiont 210A. Target DNA recognition by Cascade induces conformational changes in Cas6 and primes TniQ recruitment through its C-terminal domain. The N-terminal domain of TniQ is bound to the seam region of the TnsC spiral heptamer. Our findings provide insights into the diverse mechanisms for the recruitment of Tn7-like transposons to CRISPR effectors and will aid in the development of CASTs as gene knockin tools.
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Affiliation(s)
- Shukun Wang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Clinton Gabel
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Romana Siddique
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Leifu Chang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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5
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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 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] [What about the content of this article? (0)] [Abstract] [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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6
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Cui N, Zhang JT, Liu Y, Liu Y, Liu XY, Wang C, Huang H, Jia N. Type IV-A CRISPR-Csf complex: Assembly, dsDNA targeting, and CasDinG recruitment. Mol Cell 2023:S1097-2765(23)00420-3. [PMID: 37343553 DOI: 10.1016/j.molcel.2023.05.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/19/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023]
Abstract
Type IV CRISPR-Cas systems, which are primarily found on plasmids and exhibit a strong plasmid-targeting preference, are the only one of the six known CRISPR-Cas types for which the mechanistic details of their function remain unknown. Here, we provide high-resolution functional snapshots of type IV-A Csf complexes before and after target dsDNA binding, either in the absence or presence of CasDinG, revealing the mechanisms underlying CsfcrRNA complex assembly, "DWN" PAM-dependent dsDNA targeting, R-loop formation, and CasDinG recruitment. Furthermore, we establish that CasDinG, a signature DinG family helicase, harbors ssDNA-stimulated ATPase activity and ATP-dependent 5'-3' DNA helicase activity. In addition, we show that CasDinG unwinds the non-target strand (NTS) and target strand (TS) of target dsDNA from the CsfcrRNA complex. These molecular details advance our mechanistic understanding of type IV-A CRISPR-Csf function and should enable Csf complexes to be harnessed as genome-engineering tools for biotechnological applications.
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Affiliation(s)
- Ning Cui
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jun-Tao Zhang
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yongrui Liu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yanhong Liu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xiao-Yu Liu
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Chongyuan Wang
- Faculty of Pharmaceutical Sciences, Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen 518055, China; Center for Human Tissues and Organs Degeneration, Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen 518055, China
| | - Hongda Huang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Ning Jia
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China; Shenzhen Key Laboratory of Cell Microenvironment, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Southern University of Science and Technology, Shenzhen 518055, China; Key University Laboratory of Metabolism and Health of Guangdong, Southern University of Science and Technology, Shenzhen 518055, China.
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7
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Zhang F, Neik TX, Thomas WJW, Batley J. CRISPR-Based Genome Editing Tools: An Accelerator in Crop Breeding for a Changing Future. Int J Mol Sci 2023; 24:ijms24108623. [PMID: 37239967 DOI: 10.3390/ijms24108623] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
Genome editing is an important strategy to maintain global food security and achieve sustainable agricultural development. Among all genome editing tools, CRISPR-Cas is currently the most prevalent and offers the most promise. In this review, we summarize the development of CRISPR-Cas systems, outline their classification and distinctive features, delineate their natural mechanisms in plant genome editing and exemplify the applications in plant research. Both classical and recently discovered CRISPR-Cas systems are included, detailing the class, type, structures and functions of each. We conclude by highlighting the challenges that come with CRISPR-Cas and offer suggestions on how to tackle them. We believe the gene editing toolbox will be greatly enriched, providing new avenues for a more efficient and precise breeding of climate-resilient crops.
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Affiliation(s)
- Fangning Zhang
- College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Ting Xiang Neik
- School of Biosciences, University of Nottingham Malaysia, Semenyih 43500, Malaysia
| | - William J W Thomas
- School of Biological Sciences, University of Western Australia, Perth, WA 6009, Australia
| | - Jacqueline Batley
- School of Biological Sciences, Institute of Agriculture, University of Western Australia, Perth, WA 6009, Australia
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8
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Zhang M, Peng R, Peng Q, Liu S, Li Z, Zhang Y, Song H, Yang J, Xing X, Wang P, Qi J, Gao GF. Mechanistic insights into DNA binding and cleavage by a compact type I-F CRISPR-Cas system in bacteriophage. Proc Natl Acad Sci U S A 2023; 120:e2215098120. [PMID: 37094126 PMCID: PMC10161043 DOI: 10.1073/pnas.2215098120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 03/01/2023] [Indexed: 04/26/2023] Open
Abstract
CRISPR-Cas systems are widespread adaptive antiviral systems used in prokaryotes. Some phages, in turn, although have small genomes can economize the use of genetic space to encode compact or incomplete CRISPR-Cas systems to inhibit the host and establish infection. Phage ICP1, infecting Vibrio cholerae, encodes a compact type I-F CRISPR-Cas system to suppress the antiphage mobile genetic element in the host genome. However, the mechanism by which this compact system recognizes the target DNA and executes interference remains elusive. Here, we present the electron cryo-microscopy (cryo-EM) structures of both apo- and DNA-bound ICP1 surveillance complexes (Aka Csy complex). Unlike most other type I surveillance complexes, the ICP1 Csy complex lacks the Cas11 subunit or a structurally homologous domain, which is crucial for dsDNA binding and Cas3 activation in other type I CRISPR-Cas systems. Structural and functional analyses revealed that the compact ICP1 Csy complex alone is inefficient in binding to dsDNA targets, presumably stalled at a partial R-loop conformation. The presence of Cas2/3 facilitates dsDNA binding and allows effective dsDNA target cleavage. Additionally, we found that Pseudomonas aeruginosa Cas2/3 efficiently cleaved the dsDNA target presented by the ICP1 Csy complex, but not vice versa. These findings suggest a unique mechanism for target dsDNA binding and cleavage by the compact phage-derived CRISPR-Cas system.
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Affiliation(s)
- Manling Zhang
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing100049, China
| | - Ruchao Peng
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
| | - Qi Peng
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
| | - Sheng Liu
- Cryo-EM Centre, Department of Biology, Southern University of Science and Technology, Shenzhen518055, China
| | - Zhiteng Li
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing100049, China
| | - Yuqin Zhang
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing100049, China
| | - Hao Song
- Research Network of Immunity and Health, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing100101, China
| | - Jia Yang
- Shanxi Academy of Advanced Research and Innovation, 030032Taiyuan, Shanxi, China
| | - Xiao Xing
- Shanxi Academy of Advanced Research and Innovation, 030032Taiyuan, Shanxi, China
| | - Peiyi Wang
- Cryo-EM Centre, Department of Biology, Southern University of Science and Technology, Shenzhen518055, China
| | - Jianxun Qi
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing100049, China
| | - George F. Gao
- Chinese Academy of Sciences (CAS), Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing100049, China
- Shanxi Academy of Advanced Research and Innovation, 030032Taiyuan, Shanxi, China
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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] [What about the content of this article? (0)] [Affiliation(s)] [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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Yin P, Zhang Y, Yang L, Feng Y. Non-canonical inhibition strategies and structural basis of anti-CRISPR proteins targeting type I CRISPR-Cas systems. J Mol Biol 2023; 435:167996. [PMID: 36754343 DOI: 10.1016/j.jmb.2023.167996] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/10/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023]
Abstract
Mobile genetic elements (MGEs) such as bacteriophages and their host prokaryotes are trapped in an eternal battle against each other. To cope with foreign infection, bacteria and archaea have evolved multiple immune strategies, out of which CRISPR-Cas system is up to now the only discovered adaptive system in prokaryotes. Despite the fact that CRISPR-Cas system provides powerful and delicate protection against MGEs, MGEs have also evolved anti-CRISPR proteins (Acrs) to counteract the CRISPR-Cas immune defenses. To date, 46 families of Acrs targeting type I CRISPR-Cas system have been characterized, out of which structure information of 21 families have provided insights on their inhibition strategies. Here, we review the non-canonical inhibition strategies adopted by Acrs targeting type I CRISPR-Cas systems based on their structure information by incorporating the most recent advances in this field, and discuss our current understanding and future perspectives. The delicate interplay between type I CRISPR-Cas systems and their Acrs provides us with important insights into the ongoing fierce arms race between prokaryotic hosts and their predators.
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Affiliation(s)
- Peipei Yin
- Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, College of Chemical and Biological Engineering, Yichun University, Yichun 336000, China
| | - Yi Zhang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Lingguang Yang
- Jiangxi Provincial Key Laboratory of Natural Active Pharmaceutical Constituents, College of Chemical and Biological Engineering, Yichun University, Yichun 336000, China
| | - Yue Feng
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
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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: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Schwartz EA, McBride TM, Bravo JPK, Wrapp D, Fineran PC, Fagerlund RD, Taylor DW. Structural rearrangements allow nucleic acid discrimination by type I-D Cascade. Nat Commun 2022; 13:2829. [PMID: 35595728 DOI: 10.1038/s41467-022-30402-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/27/2022] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas systems are adaptive immune systems that protect prokaryotes from foreign nucleic acids, such as bacteriophages. Two of the most prevalent CRISPR-Cas systems include type I and type III. Interestingly, the type I-D interference proteins contain characteristic features of both type I and type III systems. Here, we present the structures of type I-D Cascade bound to both a double-stranded (ds)DNA and a single-stranded (ss)RNA target at 2.9 and 3.1 Å, respectively. We show that type I-D Cascade is capable of specifically binding ssRNA and reveal how PAM recognition of dsDNA targets initiates long-range structural rearrangements that likely primes Cas10d for Cas3′ binding and subsequent non-target strand DNA cleavage. These structures allow us to model how binding of the anti-CRISPR protein AcrID1 likely blocks target dsDNA binding via competitive inhibition of the DNA substrate engagement with the Cas10d active site. This work elucidates the unique mechanisms used by type I-D Cascade for discrimination of single-stranded and double stranded targets. Thus, our data supports a model for the hybrid nature of this complex with features of type III and type I systems. I-D CRISPR-Cascade can target both single-stranded and double-stranded nucleic acids. Here, Schwartz et. al determine these structures and reveal large-scale rearrangements that allow for target discrimination and destruction.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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18
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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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