1
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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; 300:107295. [PMID: 38641067 PMCID: PMC11127173 DOI: 10.1016/j.jbc.2024.107295] [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: 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, Norman, Oklahoma, USA
| | - Saadi Rostami
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Kole Long
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Swarmistha Devi Aribam
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Rakhi Rajan
- Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA.
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2
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Mohr G, Yao J, Park SK, Markham L, Lambowitz AM. Mechanisms used for cDNA synthesis and site-specific integration of RNA into DNA genomes by a reverse transcriptase-Cas1 fusion protein. SCIENCE ADVANCES 2024; 10:eadk8791. [PMID: 38608016 PMCID: PMC11014452 DOI: 10.1126/sciadv.adk8791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 03/08/2024] [Indexed: 04/14/2024]
Abstract
Reverse transcriptase-Cas1 (RT-Cas1) fusion proteins found in some CRISPR systems enable spacer acquisition from both RNA and DNA, but the mechanism of RNA spacer acquisition has remained unclear. Here, we found that Marinomonas mediterranea RT-Cas1/Cas2 adds short 3'-DNA (dN) tails to RNA protospacers, enabling their direct integration into CRISPR arrays as 3'-dN-RNAs or 3'-dN-RNA/cDNA duplexes at rates comparable to similarly configured DNAs. Reverse transcription of RNA protospacers is initiated at 3' proximal sites by multiple mechanisms, including recently described de novo initiation, protein priming with any dNTP, and use of short exogenous or synthesized DNA oligomer primers, enabling synthesis of near full-length cDNAs of diverse RNAs without fixed sequence requirements. The integration of 3'-dN-RNAs or single-stranded DNAs (ssDNAs) is favored over duplexes at higher protospacer concentrations, potentially relevant to spacer acquisition from abundant pathogen RNAs or ssDNA fragments generated by phage defense nucleases. Our findings reveal mechanisms for site-specifically integrating RNA into DNA genomes with potential biotechnological applications.
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Affiliation(s)
- Georg Mohr
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | | | - Laura Markham
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
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3
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Oh GS, An S, Kim S. Harnessing CRISPR-Cas adaptation for RNA recording and beyond. BMB Rep 2024; 57:40-49. [PMID: 38053290 PMCID: PMC10828431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/04/2023] [Accepted: 04/04/2023] [Indexed: 12/07/2023] Open
Abstract
Prokaryotes encode clustered regularly interspaced short palindromic repeat (CRISPR) arrays and CRISPR-associated (Cas) genes as an adaptive immune machinery. CRISPR-Cas systems effectively protect hosts from the invasion of foreign enemies, such as bacteriophages and plasmids. During a process called 'adaptation', non-self-nucleic acid fragments are acquired as spacers between repeats in the host CRISPR array, to establish immunological memory. The highly conserved Cas1-Cas2 complexes function as molecular recorders to integrate spacers in a time course manner, which can subsequently be expressed as crRNAs complexed with Cas effector proteins for the RNAguided interference pathways. In some of the RNA-targeting type III systems, Cas1 proteins are fused with reverse transcriptase (RT), indicating that RT-Cas1-Cas2 complexes can acquire RNA transcripts for spacer acquisition. In this review, we summarize current studies that focus on the molecular structure and function of the RT-fused Cas1-Cas2 integrase, and its potential applications as a directional RNA-recording tool in cells. Furthermore, we highlight outstanding questions for RT-Cas1-Cas2 studies and future directions for RNA-recording CRISPR technologies. [BMB Reports 2024; 57(1): 40-49].
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Affiliation(s)
- Gyeong-Seok Oh
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Korea
| | - Seongjin An
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Korea
- Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
| | - Sungchul Kim
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Korea
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4
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Liu L, Helal SE, Peng N. CRISPR-Cas-Based Engineering of Probiotics. BIODESIGN RESEARCH 2023; 5:0017. [PMID: 37849462 PMCID: PMC10541000 DOI: 10.34133/bdr.0017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/30/2023] [Indexed: 10/19/2023] Open
Abstract
Probiotics are the treasure of the microbiology fields. They have been widely used in the food industry, clinical treatment, and other fields. The equivocal health-promoting effects and the unknown action mechanism were the largest obstacles for further probiotic's developed applications. In recent years, various genome editing techniques have been developed and applied to explore the mechanisms and functional modifications of probiotics. As important genome editing tools, CRISPR-Cas systems that have opened new improvements in genome editing dedicated to probiotics. The high efficiency, flexibility, and specificity are the advantages of using CRISPR-Cas systems. Here, we summarize the classification and distribution of CRISPR-Cas systems in probiotics, as well as the editing tools developed on the basis of them. Then, we discuss the genome editing of probiotics based on CRISPR-Cas systems and the applications of the engineered probiotics through CRISPR-Cas systems. Finally, we proposed a design route for CRISPR systems that related to the genetically engineered probiotics.
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Affiliation(s)
- Ling Liu
- National Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
- CABIO Biotech (Wuhan) Co. Ltd., Wuhan, China
| | - Shimaa Elsayed Helal
- National Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Nan Peng
- National Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
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5
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Mohr G, Yao J, Park SK, Markham LM, Lambowitz AM. Mechanisms used for cDNA synthesis and site-specific integration of RNA into DNA genomes by a reverse transcriptase-Cas1 fusion protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555893. [PMID: 37693417 PMCID: PMC10491204 DOI: 10.1101/2023.09.01.555893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Reverse transcriptase-Cas1 (RT-Cas1) fusion proteins found in some CRISPR systems enable spacer acquisition from both RNA and DNA, but the mechanism of RNA spacer acquisition has remained unclear. Here, we found Marinomonas mediterranea RT-Cas1/Cas2 adds short 3'-DNA (dN) tails to RNA protospacers enabling their direct integration into CRISPR arrays as 3'-dN-RNA/cDNA duplexes or 3'-dN-RNAs at rates comparable to similarly configured DNAs. Reverse transcription of RNA protospacers occurs by multiple mechanisms, including recently described de novo initiation, protein priming with any dNTP, and use of short exogenous or synthesized DNA oligomer primers, enabling synthesis of cDNAs from diverse RNAs without fixed sequence requirements. The integration of 3'-dN-RNAs or single-stranded (ss) DNAs is favored over duplexes at higher protospacer concentrations, potentially relevant to spacer acquisition from abundant pathogen RNAs or ssDNA fragments generated by phage-defense nucleases. Our findings reveal novel mechanisms for site-specifically integrating RNA into DNA genomes with potential biotechnological applications.
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Affiliation(s)
- Georg Mohr
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | - Jun Yao
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | | | - Laura M. Markham
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | - Alan M. Lambowitz
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
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6
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Zabrady M, Zabrady K, Li AH, Doherty AJ. Reverse transcriptases prime DNA synthesis. Nucleic Acids Res 2023; 51:7125-7142. [PMID: 37279911 PMCID: PMC10415136 DOI: 10.1093/nar/gkad478] [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: 03/03/2023] [Revised: 05/11/2023] [Accepted: 05/19/2023] [Indexed: 06/08/2023] Open
Abstract
The discovery of reverse transcriptases (RTs) challenged the central dogma by establishing that genetic information can also flow from RNA to DNA. Although they act as DNA polymerases, RTs are distantly related to replicases that also possess de novo primase activity. Here we identify that CRISPR associated RTs (CARTs) directly prime DNA synthesis on both RNA and DNA. We demonstrate that RT-dependent priming is utilized by some CRISPR-Cas complexes to synthesise new spacers and integrate these into CRISPR arrays. Expanding our analyses, we show that primer synthesis activity is conserved in representatives of other major RT classes, including group II intron RT, telomerase and retroviruses. Together, these findings establish a conserved innate ability of RTs to catalyse de novo DNA primer synthesis, independently of accessory domains or alternative priming mechanisms, which likely plays important roles in a wide variety of biological pathways.
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Affiliation(s)
- Matej Zabrady
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Katerina Zabrady
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Arthur W H Li
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
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7
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Zhang X, An X. Adaptation by Type III CRISPR-Cas Systems: Breakthrough Findings and Open Questions. Front Microbiol 2022; 13:876174. [PMID: 35495695 PMCID: PMC9048733 DOI: 10.3389/fmicb.2022.876174] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/03/2022] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas systems acquire heritable defense memory against invading nucleic acids through adaptation. Type III CRISPR-Cas systems have unique and intriguing features of defense and are important in method development for Genetics research. We started to understand the common and unique properties of type III CRISPR-Cas adaptation in recent years. This review summarizes our knowledge regarding CRISPR-Cas adaptation with the emphasis on type III systems and discusses open questions for type III adaptation studies.
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Affiliation(s)
- Xinfu Zhang
- Department of Biochemistry and Molecular Biology, The University of Georgia, Athens, GA, United States
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, National Engineering Research Center of Tree breeding and Ecological Remediation, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- *Correspondence: Xinfu Zhang,
| | - Xinmin An
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, National Engineering Research Center of Tree breeding and Ecological Remediation, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Xinmin An,
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8
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Development and Optimization of CRISPR Prime Editing System in Photoautotrophic Cells. Molecules 2022; 27:molecules27061758. [PMID: 35335122 PMCID: PMC8948812 DOI: 10.3390/molecules27061758] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 03/02/2022] [Accepted: 03/07/2022] [Indexed: 12/04/2022] Open
Abstract
Prime editor (PE), a versatile editor that allows the insertion and deletion of arbitrary sequences, and all 12-point mutations without double-strand breaks (DSB) and a donor template, dramatically enhances research capabilities. PE combines nickase Cas9(H840A) and reverse transcriptase (RT), along with prime editing guide RNA (pegRNA). It has been reported in several plant species, but a weak editing efficiency has led to a decrease in applications. This study reports an optimized-prime editor (O-PE) for endogenous gene editing in Arabidopsis thaliana cells, with an average 1.15% editing efficiency, which is 16.4-fold higher than previously reported. Meanwhile, we observed an increase in indels when testing alternative reverse transcriptase and found out that nCas9(H840A) fused to non-functional reverse transcriptase was responsible for the increase. This work develops an efficient prime editor for plant cells and provides a blueprint for applying PE in other photoautotrophic cells, such as microalgae, that have a high industrial value.
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9
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Lee H, Sashital DG. Creating memories: molecular mechanisms of CRISPR adaptation. Trends Biochem Sci 2022; 47:464-476. [DOI: 10.1016/j.tibs.2022.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 12/22/2022]
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10
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Zhang X, Garrett S, Graveley BR, Terns MP. Unique properties of spacer acquisition by the type III-A CRISPR-Cas system. Nucleic Acids Res 2021; 50:1562-1582. [PMID: 34893878 PMCID: PMC8860593 DOI: 10.1093/nar/gkab1193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 11/12/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022] Open
Abstract
Type III CRISPR-Cas systems have a unique mode of interference, involving crRNA-guided recognition of nascent RNA and leading to DNA and RNA degradation. How type III systems acquire new CRISPR spacers is currently not well understood. Here, we characterize CRISPR spacer uptake by a type III-A system within its native host, Streptococcus thermophilus. Adaptation by the type II-A system in the same host provided a basis for comparison. Cas1 and Cas2 proteins were critical for type III adaptation but deletion of genes responsible for crRNA biogenesis or interference did not detectably change spacer uptake patterns, except those related to host counter-selection. Unlike the type II-A system, type III spacers are acquired in a PAM- and orientation-independent manner. Interestingly, certain regions of plasmids and the host genome were particularly well-sampled during type III-A, but not type II-A, spacer uptake. These regions included the single-stranded origins of rolling-circle replicating plasmids, rRNA and tRNA encoding gene clusters, promoter regions of expressed genes and 5′ UTR regions involved in transcription attenuation. These features share the potential to form DNA secondary structures, suggesting a preferred substrate for type III adaptation. Lastly, the type III-A system adapted to and protected host cells from lytic phage infection.
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Affiliation(s)
- Xinfu Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Sandra Garrett
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Brenton R Graveley
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Michael P Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.,Department of Microbiology, University of Georgia, Athens, GA 30602, USA.,Department of Genetics, University of Georgia, Athens, GA 30602, USA
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11
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González-Delgado A, Mestre MR, Martínez-Abarca F, Toro N. Prokaryotic reverse transcriptases: from retroelements to specialized defense systems. FEMS Microbiol Rev 2021; 45:fuab025. [PMID: 33983378 PMCID: PMC8632793 DOI: 10.1093/femsre/fuab025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/07/2021] [Indexed: 12/30/2022] Open
Abstract
Reverse transcriptases (RTs) catalyze the polymerization of DNA from an RNA template. These enzymes were first discovered in RNA tumor viruses in 1970, but it was not until 1989 that they were found in prokaryotes as a key component of retrons. Apart from RTs encoded by the 'selfish' mobile retroelements known as group II introns, prokaryotic RTs are extraordinarily diverse, but their function has remained elusive. However, recent studies have revealed that different lineages of prokaryotic RTs, including retrons, those associated with CRISPR-Cas systems, Abi-like RTs and other yet uncharacterized RTs, are key components of different lines of defense against phages and other mobile genetic elements. Prokaryotic RTs participate in various antiviral strategies, including abortive infection (Abi), in which the infected cell is induced to commit suicide to protect the host population, adaptive immunity, in which a memory of previous infection is used to build an efficient defense, and other as yet unidentified mechanisms. These prokaryotic enzymes are attracting considerable attention, both for use in cutting-edge technologies, such as genome editing, and as an emerging research topic. In this review, we discuss what is known about prokaryotic RTs, and the exciting evidence for their domestication from retroelements to create specialized defense systems.
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Affiliation(s)
- Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Mario Rodríguez Mestre
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
- Department of Biochemistry, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC-UAM, Madrid, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
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12
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Kolesnik MV, Fedorova I, Karneyeva KA, Artamonova DN, Severinov KV. Type III CRISPR-Cas Systems: Deciphering the Most Complex Prokaryotic Immune System. BIOCHEMISTRY. BIOKHIMIIA 2021; 86:1301-1314. [PMID: 34903162 PMCID: PMC8527444 DOI: 10.1134/s0006297921100114] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/24/2021] [Accepted: 08/30/2021] [Indexed: 12/18/2022]
Abstract
The emergence and persistence of selfish genetic elements is an intrinsic feature of all living systems. Cellular organisms have evolved a plethora of elaborate defense systems that limit the spread of such genetic parasites. CRISPR-Cas are RNA-guided defense systems used by prokaryotes to recognize and destroy foreign nucleic acids. These systems acquire and store fragments of foreign nucleic acids and utilize the stored sequences as guides to recognize and destroy genetic invaders. CRISPR-Cas systems have been extensively studied, as some of them are used in various genome editing technologies. Although Type III CRISPR-Cas systems are among the most common CRISPR-Cas systems, they are also some of the least investigated ones, mostly due to the complexity of their action compared to other CRISPR-Cas system types. Type III effector complexes specifically recognize and cleave RNA molecules. The recognition of the target RNA activates the effector large subunit - the so-called CRISPR polymerase - which cleaves DNA and produces small cyclic oligonucleotides that act as signaling molecules to activate auxiliary effectors, notably non-specific RNases. In this review, we provide a historical overview of the sometimes meandering pathway of the Type III CRISPR research. We also review the current data on the structures and activities of Type III CRISPR-Cas systems components, their biological roles, and evolutionary history. Finally, using structural modeling with AlphaFold2, we show that the archaeal HRAMP signature protein, which heretofore has had no assigned function, is a degenerate relative of Type III CRISPR-Cas signature protein Cas10, suggesting that HRAMP systems have descended from Type III CRISPR-Cas systems or their ancestors.
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Affiliation(s)
- Matvey V Kolesnik
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.
| | - Iana Fedorova
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, 195251, Russia.
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
| | - Karyna A Karneyeva
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.
| | - Daria N Artamonova
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.
| | - Konstantin V Severinov
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia.
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
- Waksman Institute of Microbiology, Piscataway, NJ 08854, USA
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13
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Guzmán NM, Esquerra-Ruvira B, Mojica FJM. Digging into the lesser-known aspects of CRISPR biology. Int Microbiol 2021; 24:473-498. [PMID: 34487299 PMCID: PMC8616872 DOI: 10.1007/s10123-021-00208-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 12/26/2022]
Abstract
A long time has passed since regularly interspaced DNA repeats were discovered in prokaryotes. Today, those enigmatic repetitive elements termed clustered regularly interspaced short palindromic repeats (CRISPR) are acknowledged as an emblematic part of multicomponent CRISPR-Cas (CRISPR associated) systems. These systems are involved in a variety of roles in bacteria and archaea, notably, that of conferring protection against transmissible genetic elements through an adaptive immune-like response. This review summarises the present knowledge on the diversity, molecular mechanisms and biology of CRISPR-Cas. We pay special attention to the most recent findings related to the determinants and consequences of CRISPR-Cas activity. Research on the basic features of these systems illustrates how instrumental the study of prokaryotes is for understanding biology in general, ultimately providing valuable tools for diverse fields and fuelling research beyond the mainstream.
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Affiliation(s)
- Noemí M Guzmán
- Dpto. Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Belén Esquerra-Ruvira
- Dpto. Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Francisco J M Mojica
- Dpto. Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain. .,Instituto Multidisciplinar para el Estudio del Medio, Universidad de Alicante, Alicante, Spain.
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14
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Structural coordination between active sites of a CRISPR reverse transcriptase-integrase complex. Nat Commun 2021; 12:2571. [PMID: 33958590 PMCID: PMC8102632 DOI: 10.1038/s41467-021-22900-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/26/2021] [Indexed: 02/03/2023] Open
Abstract
CRISPR-Cas systems provide adaptive immunity in bacteria and archaea, beginning with integration of foreign sequences into the host CRISPR genomic locus and followed by transcription and maturation of CRISPR RNAs (crRNAs). In some CRISPR systems, a reverse transcriptase (RT) fusion to the Cas1 integrase and Cas6 maturase creates a single protein that enables concerted sequence integration and crRNA production. To elucidate how the RT-integrase organizes distinct enzymatic activities, we present the cryo-EM structure of a Cas6-RT-Cas1-Cas2 CRISPR integrase complex. The structure reveals a heterohexamer in which the RT directly contacts the integrase and maturase domains, suggesting functional coordination between all three active sites. Together with biochemical experiments, our data support a model of sequential enzymatic activities that enable CRISPR sequence acquisition from RNA and DNA substrates. These findings highlight an expanded capacity of some CRISPR systems to acquire diverse sequences that direct CRISPR-mediated interference.
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15
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Mestre MR, González-Delgado A, Gutiérrez-Rus LI, Martínez-Abarca F, Toro N. Systematic prediction of genes functionally associated with bacterial retrons and classification of the encoded tripartite systems. Nucleic Acids Res 2021; 48:12632-12647. [PMID: 33275130 PMCID: PMC7736814 DOI: 10.1093/nar/gkaa1149] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/05/2020] [Accepted: 11/10/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial retrons consist of a reverse transcriptase (RT) and a contiguous non-coding RNA (ncRNA) gene. One third of annotated retrons carry additional open reading frames (ORFs), the contribution and significance of which in retron biology remains to be determined. In this study we developed a computational pipeline for the systematic prediction of genes specifically associated with retron RTs based on a previously reported large dataset representative of the diversity of prokaryotic RTs. We found that retrons generally comprise a tripartite system composed of the ncRNA, the RT and an additional protein or RT-fused domain with diverse enzymatic functions. These retron systems are highly modular, and their components have coevolved to different extents. Based on the additional module, we classified retrons into 13 types, some of which include additional variants. Our findings provide a basis for future studies on the biological function of retrons and for expanding their biotechnological applications.
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Affiliation(s)
- Mario Rodríguez Mestre
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Alejandro González-Delgado
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Luis I Gutiérrez-Rus
- Departamento de Química Física. Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Francisco Martínez-Abarca
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
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16
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Affiliation(s)
- Christine Pourcel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
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17
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Artamonova D, Karneyeva K, Medvedeva S, Klimuk E, Kolesnik M, Yasinskaya A, Samolygo A, Severinov K. Spacer acquisition by Type III CRISPR-Cas system during bacteriophage infection of Thermus thermophilus. Nucleic Acids Res 2020; 48:9787-9803. [PMID: 32821943 PMCID: PMC7515739 DOI: 10.1093/nar/gkaa685] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/01/2020] [Accepted: 08/05/2020] [Indexed: 12/21/2022] Open
Abstract
Type III CRISPR–Cas systems provide immunity to foreign DNA by targeting its transcripts. Target recognition activates RNases and DNases that may either destroy foreign DNA directly or elicit collateral damage inducing death of infected cells. While some Type III systems encode a reverse transcriptase to acquire spacers from foreign transcripts, most contain conventional spacer acquisition machinery found in DNA-targeting systems. We studied Type III spacer acquisition in phage-infected Thermus thermophilus, a bacterium that lacks either a standalone reverse transcriptase or its fusion to spacer integrase Cas1. Cells with spacers targeting a subset of phage transcripts survived the infection, indicating that Type III immunity does not operate through altruistic suicide. In the absence of selection spacers were acquired from both strands of phage DNA, indicating that no mechanism ensuring acquisition of RNA-targeting spacers exists. Spacers that protect the host from the phage demonstrate a very strong strand bias due to positive selection during infection. Phages that escaped Type III interference accumulated deletions of integral number of codons in an essential gene and much longer deletions in a non-essential gene. This and the fact that Type III immunity can be provided by plasmid-borne mini-arrays open ways for genomic manipulation of Thermus phages.
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Affiliation(s)
- Daria Artamonova
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Karyna Karneyeva
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Sofia Medvedeva
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Evgeny Klimuk
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Matvey Kolesnik
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Anna Yasinskaya
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Aleksei Samolygo
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Konstantin Severinov
- Center of Life Science, Skolkovo Institute of Science and Technology, Moscow 121205, Russia.,Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.,Waksman Institute, Rutgers, The State University of New Jersey, NJ 08854 USA
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18
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Zink IA, Wimmer E, Schleper C. Heavily Armed Ancestors: CRISPR Immunity and Applications in Archaea with a Comparative Analysis of CRISPR Types in Sulfolobales. Biomolecules 2020; 10:E1523. [PMID: 33172134 PMCID: PMC7694759 DOI: 10.3390/biom10111523] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Prokaryotes are constantly coping with attacks by viruses in their natural environments and therefore have evolved an impressive array of defense systems. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is an adaptive immune system found in the majority of archaea and about half of bacteria which stores pieces of infecting viral DNA as spacers in genomic CRISPR arrays to reuse them for specific virus destruction upon a second wave of infection. In detail, small CRISPR RNAs (crRNAs) are transcribed from CRISPR arrays and incorporated into type-specific CRISPR effector complexes which further degrade foreign nucleic acids complementary to the crRNA. This review gives an overview of CRISPR immunity to newcomers in the field and an update on CRISPR literature in archaea by comparing the functional mechanisms and abundances of the diverse CRISPR types. A bigger fraction is dedicated to the versatile and prevalent CRISPR type III systems, as tremendous progress has been made recently using archaeal models in discerning the controlled molecular mechanisms of their unique tripartite mode of action including RNA interference, DNA interference and the unique cyclic-oligoadenylate signaling that induces promiscuous RNA shredding by CARF-domain ribonucleases. The second half of the review spotlights CRISPR in archaea outlining seminal in vivo and in vitro studies in model organisms of the euryarchaeal and crenarchaeal phyla, including the application of CRISPR-Cas for genome editing and gene silencing. In the last section, a special focus is laid on members of the crenarchaeal hyperthermophilic order Sulfolobales by presenting a thorough comparative analysis about the distribution and abundance of CRISPR-Cas systems, including arrays and spacers as well as CRISPR-accessory proteins in all 53 genomes available to date. Interestingly, we find that CRISPR type III and the DNA-degrading CRISPR type I complexes co-exist in more than two thirds of these genomes. Furthermore, we identified ring nuclease candidates in all but two genomes and found that they generally co-exist with the above-mentioned CARF domain ribonucleases Csx1/Csm6. These observations, together with published literature allowed us to draft a working model of how CRISPR-Cas systems and accessory proteins cross talk to establish native CRISPR anti-virus immunity in a Sulfolobales cell.
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19
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Sasnauskas G, Siksnys V. CRISPR adaptation from a structural perspective. Curr Opin Struct Biol 2020; 65:17-25. [PMID: 32570107 DOI: 10.1016/j.sbi.2020.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/20/2020] [Accepted: 05/21/2020] [Indexed: 12/24/2022]
Abstract
Bacterial CRISPR-Cas systems provide adaptive immunity against viruses and other mobile genome elements. During the adaptation step cells become immunized by insertion of short fragments of foreign DNA, termed spacers, into the genomic region called a CRISPR array. Selection, processing and insertion of new spacers is an elaborate and precisely orchestrated reaction, which relies on the Cas1-Cas2 integrase complex and accessory proteins that vary among different types of CRISPR-Cas systems. This review focuses on CRISPR adaptation from the structural perspective, with the spotlight on adaptation proteins employed by type I and type II CRISPR-Cas systems.
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Affiliation(s)
- Giedrius Sasnauskas
- Institute of Biotechnology, Vilnius University, Sauletekio Av. 7, Vilnius 10257, Lithuania
| | - Virginijus Siksnys
- Institute of Biotechnology, Vilnius University, Sauletekio Av. 7, Vilnius 10257, Lithuania.
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20
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Real-time observation of CRISPR spacer acquisition by Cas1-Cas2 integrase. Nat Struct Mol Biol 2020; 27:489-499. [PMID: 32367067 PMCID: PMC7241818 DOI: 10.1038/s41594-020-0415-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/16/2020] [Indexed: 01/13/2023]
Abstract
Cas1 integrase associates with Cas2 to insert short DNA fragments into a CRISPR array, establishing nucleic acid memory in prokaryotes. Here we applied single-molecule FRET methods to the Enterococcus faecalis (Efa) Cas1–Cas2 system to establish a kinetic framework describing target-searching, integration, and post-synapsis events. EfaCas1–Cas2 on its own is not able to find the CRISPR repeat in the CRISPR array; it only does so after prespacer loading. The leader sequence adjacent to the repeat further stabilizes EfaCas1–Cas2 contacts, enabling leader-side integration and subsequent spacer-side integration. The resulting post-synaptic complex has a surprisingly short mean lifetime. Remarkably, transcription efficiently resolves the postsynaptic complex and we predict that this is a conserved mechanism that ensures efficient and directional spacer integration in many CRISPR systems. Overall, our study provides a complete model of spacer acquisition, which can be harnessed for DNA-based information storage and cell lineage tracing technologies.
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