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Uddin TM, Chakraborty AJ, Khusro A, Zidan BRM, Mitra S, Emran TB, Dhama K, Ripon MKH, Gajdács M, Sahibzada MUK, Hossain MJ, Koirala N. Antibiotic resistance in microbes: History, mechanisms, therapeutic strategies and future prospects. J Infect Public Health 2021; 14:1750-1766. [PMID: 34756812 DOI: 10.1016/j.jiph.2021.10.020] [Citation(s) in RCA: 216] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/04/2021] [Accepted: 10/14/2021] [Indexed: 12/22/2022] Open
Abstract
Antibiotics have been used to cure bacterial infections for more than 70 years, and these low-molecular-weight bioactive agents have also been used for a variety of other medicinal applications. In the battle against microbes, antibiotics have certainly been a blessing to human civilization by saving millions of lives. Globally, infections caused by multidrug-resistant (MDR) bacteria are on the rise. Antibiotics are being used to combat diversified bacterial infections. Synthetic biology techniques, in combination with molecular, functional genomic, and metagenomic studies of bacteria, plants, and even marine invertebrates are aimed at unlocking the world's natural products faster than previous methods of antibiotic discovery. There are currently only few viable remedies, potential preventive techniques, and a limited number of antibiotics, thereby necessitating the discovery of innovative medicinal approaches and antimicrobial therapies. MDR is also facilitated by biofilms, which makes infection control more complex. In this review, we have spotlighted comprehensively various aspects of antibiotics viz. overview of antibiotics era, mode of actions of antibiotics, development and mechanisms of antibiotic resistance in bacteria, and future strategies to fight the emerging antimicrobial resistant threat.
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Affiliation(s)
- Tanvir Mahtab Uddin
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh.
| | - Arka Jyoti Chakraborty
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh.
| | - Ameer Khusro
- Research Department of Plant Biology and Biotechnology, Loyola College, Nungambakkam, Chennai, Tamil Nadu, India.
| | - Bm Redwan Matin Zidan
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh.
| | - Saikat Mitra
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh.
| | - Talha Bin Emran
- Department of Pharmacy, BGC Trust University Bangladesh, Chittagong 4381, Bangladesh.
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, Uttar Pradesh, India.
| | - Md Kamal Hossain Ripon
- Department of Pharmacy, Mawlana Bhashani Science and Technology University, Santosh, Tangail 1902, Bangladesh.
| | - Márió Gajdács
- Department of Oral Biology and Experimental Dental Research, Faculty of Dentistry, University of Szeged, 6720 Szeged, Hungary.
| | | | - Md Jamal Hossain
- Department of Pharmacy, State University of Bangladesh, 77 Satmasjid Road, Dhanmondi, Dhaka 1205, Bangladesh.
| | - Niranjan Koirala
- Department of Natural Products Research, Dr. Koirala Research Institute for Biotechnology and Biodiversity, Kathmandu 44600, Nepal.
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Gholizadeh P, Köse Ş, Dao S, Ganbarov K, Tanomand A, Dal T, Aghazadeh M, Ghotaslou R, Ahangarzadeh Rezaee M, Yousefi B, Samadi Kafil H. How CRISPR-Cas System Could Be Used to Combat Antimicrobial Resistance. Infect Drug Resist 2020; 13:1111-1121. [PMID: 32368102 PMCID: PMC7182461 DOI: 10.2147/idr.s247271] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 03/31/2020] [Indexed: 12/26/2022] Open
Abstract
Rapid emergence of antibiotic-resistant bacteria has made it harder for us to combat infectious diseases and to develop new antibiotics. The clustered regularly interspaced short palindromic repeats - CRISPR-associated (CRISPR-Cas) system, as a bacterial adaptive immune system, is recognized as one of the new strategies for controlling antibiotic-resistant strains. The programmable Cas nuclease of this system used against bacterial genomic sequences could be lethal or could help reduce resistance of bacteria to antibiotics. Therefore, this study aims to review using the CRISPR-Cas system to promote sensitizing bacteria to antibiotics. We envision that CRISPR-Cas approaches may open novel ways for the development of smart antibiotics, which could eliminate multidrug-resistant (MDR) pathogens and differentiate between beneficial and pathogenic microorganisms. These systems can be exploited to quantitatively and selectively eliminate individual bacterial strains based on a sequence-specific manner, creating opportunities in the treatment of MDR infections, the study of microbial consortia, and the control of industrial fermentation.
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Affiliation(s)
- Pourya Gholizadeh
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Şükran Köse
- Department of Infectious Diseases and Clinical Microbiology, University of Health Sciences, Tepecik Training and Research Hospital, İzmir, Turkey
| | - Sounkalo Dao
- Faculté de Médecine, de Pharmacie et d’Odonto-Stomatologie (FMPOS), University of Bamako, Bamako, Mali
| | - Khudaverdi Ganbarov
- Department of Microbiology, Baku State University, Baku, Republic of Azerbaijan
| | - Asghar Tanomand
- Department of Basic Sciences, Maragheh University of Medical Sciences, Maragheh, Iran
| | - Tuba Dal
- Department of Clinical Microbiology, Faculty of Medicine, Ankara Yildirim Beyazit University, Ankara, Turkey
| | - Mohammad Aghazadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Reza Ghotaslou
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Bahman Yousefi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hossein Samadi Kafil
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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3
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Reversible Gene Expression Control in Yersinia pestis by Using an Optimized CRISPR Interference System. Appl Environ Microbiol 2019; 85:AEM.00097-19. [PMID: 30979834 DOI: 10.1128/aem.00097-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 04/02/2019] [Indexed: 12/26/2022] Open
Abstract
Many genes in the bacterial pathogen Yersinia pestis, the causative agent of three plague pandemics, remain uncharacterized, greatly hampering the development of measures for plague prevention and control. Clustered regularly interspaced short palindromic repeat interference (CRISPRi) has been shown to be an effective tool for gene knockdown in model bacteria. In this system, a catalytically dead Cas9 (dCas9) and a small guide RNA (sgRNA) form a complex, binding to the specific DNA target through base pairing, thereby impeding RNA polymerase binding and causing target gene repression. Here, we introduce an optimized CRISPRi system using Streptococcus pyogenes Cas9-derived dCas9 for gene knockdown in Y. pestis Multiple genes harbored on either the chromosome or plasmids of Y. pestis were efficiently knocked down (up to 380-fold) in a strictly anhydrotetracycline-inducible manner using this CRISPRi approach. Knockdown of hmsH (responsible for biofilm formation) or cspB (encoding a cold shock protein) resulted in greatly decreased biofilm formation or impaired cold tolerance in in vitro phenotypic assays. Furthermore, silencing of the virulence-associated genes yscB or ail using this CRISPRi system resulted in attenuation of virulence in HeLa cells and mice similar to that previously reported for yscB and ail null mutants. Taken together, our results confirm that this optimized CRISPRi system can reversibly and efficiently repress the expression of target genes in Y. pestis, providing an alternative to conventional gene knockdown techniques, as well as a strategy for high-throughput phenotypic screening of Y. pestis genes with unknown functions.IMPORTANCE Yersinia pestis is a lethal pathogen responsible for millions of human deaths in history. It has also attracted much attention for potential uses as a bioweapon or bioterrorism agent, against which new vaccines are desperately needed. However, many Y. pestis genes remain uncharacterized, greatly hampering the development of measures for plague prevention and control. Clustered regularly interspaced short palindromic repeat interference (CRISPRi) has been successfully used in a variety of bacteria in functional genomic studies, but no such genetic tool has been reported in Y. pestis Here, we systematically optimized the CRISPRi approach for use in Y. pestis, which ultimately repressed target gene expression with high efficiency in a reversible manner. Knockdown of functional genes using this method produced phenotypes that were readily detected by in vitro assays, cell infection assays, and mouse infection experiments. This is a report of a CRISPRi approach in Y. pestis and highlights the potential use of this approach in high-throughput functional genomics studies of this pathogen.
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Ahmed W, Hafeez MA, Ahmad R, Mahmood S. CRISPR-Cas system in regulation of immunity and virulence of bacterial pathogens. GENE REPORTS 2018. [DOI: 10.1016/j.genrep.2018.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Weissman JL, Fagan WF, Johnson PLF. Selective Maintenance of Multiple CRISPR Arrays Across Prokaryotes. CRISPR J 2018; 1:405-413. [PMID: 31021246 DOI: 10.1089/crispr.2018.0034] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prokaryotes are under nearly constant attack by viral pathogens. To protect against this threat of infection, bacteria and archaea have evolved a wide array of defense mechanisms, singly and in combination. While immune diversity in a single organism likely reduces the chance of pathogen evolutionary escape, it remains puzzling why many prokaryotes also have multiple, seemingly redundant, copies of the same type of immune system. Here, we focus on the highly flexible CRISPR adaptive immune system, which is present in multiple copies in a surprising 28% of the prokaryotic genomes in RefSeq. We use a comparative genomics approach looking across all prokaryotes to demonstrate that on average, organisms are under selection to maintain more than one CRISPR array. Given this surprising conclusion, we consider several hypotheses concerning the source of selection and include a theoretical analysis of the possibility that a trade-off between memory span and learning speed could select for both "long-term memory" and "short-term memory" CRISPR arrays.
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Affiliation(s)
- Jake L Weissman
- Department of Biology, University of Maryland College Park , College Park, Maryland
| | - William F Fagan
- Department of Biology, University of Maryland College Park , College Park, Maryland
| | - Philip L F Johnson
- Department of Biology, University of Maryland College Park , College Park, Maryland
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Goren MG, Doron S, Globus R, Amitai G, Sorek R, Qimron U. Repeat Size Determination by Two Molecular Rulers in the Type I-E CRISPR Array. Cell Rep 2017; 16:2811-2818. [PMID: 27626652 PMCID: PMC5039180 DOI: 10.1016/j.celrep.2016.08.043] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/01/2016] [Accepted: 08/12/2016] [Indexed: 12/24/2022] Open
Abstract
Prokaryotic adaptive immune systems are composed of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins. These systems adapt to new threats by integrating short nucleic acids, termed spacers, into the CRISPR array. The functional motifs in the repeat and the mechanism by which a constant repeat size is maintained are still elusive. Here, through a series of mutations within the repeat of the CRISPR-Cas type I-E, we identify motifs that are crucial for adaptation and show that they serve as anchor sites for two molecular rulers determining the size of the new repeat. Adaptation products from various repeat mutants support a model in which two motifs in the repeat bind to two different sites in the adaptation complex that are 8 and 16 bp away from the active site. This model significantly extends our understanding of the adaptation process and broadens the scope of its applications. Inverted repeats in the type I-E CRISPR-Cas system are essential for adaptation Each inverted repeat encodes a motif serving as an anchor site for a molecular ruler These molecular rulers determine the spacer insertion site regardless of the sequence The findings support a model considering all known steps in spacer adaptation
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Affiliation(s)
- Moran G Goren
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Shany Doron
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rea Globus
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Gil Amitai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Udi Qimron
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, 69978 Tel Aviv, Israel.
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7
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Goren M, Yosef I, Qimron U. Sensitizing pathogens to antibiotics using the CRISPR-Cas system. Drug Resist Updat 2016; 30:1-6. [PMID: 28363331 DOI: 10.1016/j.drup.2016.11.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/20/2016] [Accepted: 11/22/2016] [Indexed: 01/10/2023]
Abstract
The extensive use of antibiotics over the last century has resulted in a significant artificial selection pressure for antibiotic-resistant pathogens to evolve. Various strategies to fight these pathogens have been introduced including new antibiotics, naturally-derived enzymes/peptides that specifically target pathogens and bacteriophages that lyse these pathogens. A new tool has recently been introduced in the fight against drug-resistant pathogens-the prokaryotic defense mechanism-clustered regularly interspaced short palindromic repeats-CRISPR associated (CRISPR-Cas) system. The CRISPR-Cas system acts as a nuclease that can be guided to cleave any target DNA, allowing sophisticated, yet feasible, manipulations of pathogens. Here, we review pioneering studies that use the CRISPR-Cas system to specifically edit bacterial populations, eliminate their resistance genes and combine these two strategies in order to produce an artificial selection pressure for antibiotic-sensitive pathogens. We suggest that intelligent design of this system, along with efficient delivery tools into pathogens, may significantly reduce the threat of antibiotic-resistant pathogens.
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Affiliation(s)
- Moran Goren
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ido Yosef
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Udi Qimron
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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8
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Goldberg GW, Marraffini LA. Resistance and tolerance to foreign elements by prokaryotic immune systems - curating the genome. Nat Rev Immunol 2016; 15:717-24. [PMID: 26494050 DOI: 10.1038/nri3910] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To engage in adaptive symbioses or genetic exchange, organisms must interact with foreign, non-self elements despite the risks of predation and parasitism. By surveying the interface between self and non-self, immune systems can help ensure the benevolence of these interactions without isolating their hosts altogether. In this Essay, we examine prokaryotic restriction-modification and CRISPR-Cas (clustered, regularly interspaced palindromic repeat-CRISPR-associated proteins) activities and discuss their analogy to mammalian immune pathways. We further explain how their capacities for resistance and tolerance are optimized to reduce parasitism and immunopathology during encounters with non-self.
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Affiliation(s)
- Gregory W Goldberg
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York City, New York 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York City, New York 10065, USA
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Rollie C, Schneider S, Brinkmann AS, Bolt EL, White MF. Intrinsic sequence specificity of the Cas1 integrase directs new spacer acquisition. eLife 2015; 4. [PMID: 26284603 PMCID: PMC4574026 DOI: 10.7554/elife.08716] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 08/17/2015] [Indexed: 11/13/2022] Open
Abstract
The adaptive prokaryotic immune system CRISPR-Cas provides RNA-mediated protection from invading genetic elements. The fundamental basis of the system is the ability to capture small pieces of foreign DNA for incorporation into the genome at the CRISPR locus, a process known as Adaptation, which is dependent on the Cas1 and Cas2 proteins. We demonstrate that Cas1 catalyses an efficient trans-esterification reaction on branched DNA substrates, which represents the reverse- or disintegration reaction. Cas1 from both Escherichia coli and Sulfolobus solfataricus display sequence specific activity, with a clear preference for the nucleotides flanking the integration site at the leader-repeat 1 boundary of the CRISPR locus. Cas2 is not required for this activity and does not influence the specificity. This suggests that the inherent sequence specificity of Cas1 is a major determinant of the adaptation process.
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Affiliation(s)
- Clare Rollie
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
| | - Stefanie Schneider
- Faculty of Medicine, Institute of Cell Biology, University of Duisburg-Essen, Essen, Germany
| | - Anna Sophie Brinkmann
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Edward L Bolt
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Malcolm F White
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, United Kingdom
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10
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Using the CRISPR-Cas System to Positively Select Mutants in Genes Essential for Its Function. Methods Mol Biol 2015. [PMID: 25981477 DOI: 10.1007/978-1-4939-2687-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR associated proteins (Cas) comprise a prokaryotic adaptive defense system against foreign nucleic acids. This defense is mediated by Cas proteins, which are guided by sequences flanked by the repeats, called spacers, to target nucleic acids. Spacers designed against the prokaryotic self chromosome are lethal to the prokaryotic cell. This self-killing of the bacterium by its own CRISPR-Cas system can be used to positively select genes that participate in this killing, as their absence will result in viable cells. Here we describe a positive selection assay that uses this feature to identify E. coli mutants encoding an inactive CRISPR-Cas system. The procedure includes establishment of an assay that detects this self-killing, generation of transposon insertion mutants in random genes, and selection of viable mutants, suspected as required for this lethal activity. This procedure enabled us to identify a novel gene, htpG, that is required for the activity of the CRISPR-Cas system. The procedures described here can be adjusted to various organisms to identify genes required for their CRISPR-Cas activity.
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Abstract
The CRISPRs (clustered regularly interspaced short palindromic repeats) and their associated Cas (CRISPR-associated) proteins are a prokaryotic adaptive defence system against foreign nucleic acids. The CRISPR array comprises short repeats flanking short segments, called 'spacers', which are derived from foreign nucleic acids. The process of spacer insertion into the CRISPR array is termed 'adaptation'. Adaptation allows the system to rapidly evolve against emerging threats. In the present article, we review the most recent studies on the adaptation process, and focus primarily on the subtype I-E CRISPR-Cas system of Escherichia coli.
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12
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Barrangou R, Marraffini LA. CRISPR-Cas systems: Prokaryotes upgrade to adaptive immunity. Mol Cell 2014; 54:234-44. [PMID: 24766887 DOI: 10.1016/j.molcel.2014.03.011] [Citation(s) in RCA: 483] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR), and associated proteins (Cas) comprise the CRISPR-Cas system, which confers adaptive immunity against exogenic elements in many bacteria and most archaea. CRISPR-mediated immunization occurs through the uptake of DNA from invasive genetic elements such as plasmids and viruses, followed by its integration into CRISPR loci. These loci are subsequently transcribed and processed into small interfering RNAs that guide nucleases for specific cleavage of complementary sequences. Conceptually, CRISPR-Cas shares functional features with the mammalian adaptive immune system, while also exhibiting characteristics of Lamarckian evolution. Because immune markers spliced from exogenous agents are integrated iteratively in CRISPR loci, they constitute a genetic record of vaccination events and reflect environmental conditions and changes over time. Cas endonucleases, which can be reprogrammed by small guide RNAs have shown unprecedented potential and flexibility for genome editing and can be repurposed for numerous DNA targeting applications including transcriptional control.
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Affiliation(s)
- Rodolphe Barrangou
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC 27695, USA.
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13
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Heler R, Marraffini LA, Bikard D. Adapting to new threats: the generation of memory by CRISPR-Cas immune systems. Mol Microbiol 2014; 93:1-9. [PMID: 24806524 DOI: 10.1111/mmi.12640] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2014] [Indexed: 12/11/2022]
Abstract
Clustered, regularly interspaced, short palindromic repeats (CRISPR) loci and their associated genes (cas) confer bacteria and archaea with adaptive immunity against phages and other invading genetic elements. A fundamental requirement of any immune system is the ability to build a memory of past infections in order to deal more efficiently with recurrent infections. The adaptive feature of CRISPR-Cas immune systems relies on their ability to memorize DNA sequences of invading molecules and integrate them in between the repetitive sequences of the CRISPR array in the form of 'spacers'. The transcription of a spacer generates a small antisense RNA that is used by RNA-guided Cas nucleases to cleave the invading nucleic acid in order to protect the cell from infection. The acquisition of new spacers allows the CRISPR-Cas immune system to rapidly adapt against new threats and is therefore termed 'adaptation'. Recent studies have begun to elucidate the genetic requirements for adaptation and have demonstrated that rather than being a stochastic process, the selection of new spacers is influenced by several factors. We review here our current knowledge of the CRISPR adaptation mechanism.
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Affiliation(s)
- Robert Heler
- Laboratory of Bacteriology, The Rockefeller University, New York, NY, 10065, USA
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14
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DNA motifs determining the efficiency of adaptation into the Escherichia coli CRISPR array. Proc Natl Acad Sci U S A 2013; 110:14396-401. [PMID: 23940313 DOI: 10.1073/pnas.1300108110] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated proteins constitute a recently identified prokaryotic defense system against invading nucleic acids. DNA segments, termed protospacers, are integrated into the CRISPR array in a process called adaptation. Here, we establish a PCR-based assay that enables evaluating the adaptation efficiency of specific spacers into the type I-E Escherichia coli CRISPR array. Using this assay, we provide direct evidence that the protospacer adjacent motif along with the first base of the protospacer (5'-AAG) partially affect the efficiency of spacer acquisition. Remarkably, we identified a unique dinucleotide, 5'-AA, positioned at the 3' end of the spacer, that enhances efficiency of the spacer's acquisition. Insertion of this dinucleotide increased acquisition efficiency of two different spacers. DNA sequencing of newly adapted CRISPR arrays revealed that the position of the newly identified motif with respect to the 5'-AAG is important for affecting acquisition efficiency. Analysis of approximately 1 million spacers showed that this motif is overrepresented in frequently acquired spacers compared with those acquired rarely. Our results represent an example of a short nonprotospacer adjacent motif sequence that affects acquisition efficiency and suggest that other as yet unknown motifs affect acquisition efficiency in other CRISPR systems as well.
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Evolutionary dynamics of the prokaryotic adaptive immunity system CRISPR-Cas in an explicit ecological context. J Bacteriol 2013; 195:3834-44. [PMID: 23794616 DOI: 10.1128/jb.00412-13] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A stochastic, agent-based mathematical model of the coevolution of the archaeal and bacterial adaptive immunity system, CRISPR-Cas, and lytic viruses shows that CRISPR-Cas immunity can stabilize the virus-host coexistence rather than leading to the extinction of the virus. In the model, CRISPR-Cas immunity does not specifically promote viral diversity, presumably because the selection pressure on each single proto-spacer is too weak. However, the overall virus diversity in the presence of CRISPR-Cas grows due to the increase of the host and, accordingly, the virus population size. Above a threshold value of total viral diversity, which is proportional to the viral mutation rate and population size, the CRISPR-Cas system becomes ineffective and is lost due to the associated fitness cost. Our previous modeling study has suggested that the ubiquity of CRISPR-Cas in hyperthermophiles, which contrasts its comparative low prevalence in mesophiles, is due to lower rates of mutation fixation in thermal habitats. The present findings offer a complementary, simpler perspective on this contrast through the larger population sizes of mesophiles compared to hyperthermophiles, because of which CRISPR-Cas can become ineffective in mesophiles. The efficacy of CRISPR-Cas sharply increases with the number of proto-spacers per viral genome, potentially explaining the low information content of the proto-spacer-associated motif (PAM) that is required for spacer acquisition by CRISPR-Cas because a higher specificity would restrict the number of spacers available to CRISPR-Cas, thus hampering immunity. The very existence of the PAM might reflect the tradeoff between the requirement of diverse spacers for efficient immunity and avoidance of autoimmunity.
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16
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Koonin EV, Makarova KS. CRISPR-Cas: evolution of an RNA-based adaptive immunity system in prokaryotes. RNA Biol 2013; 10:679-86. [PMID: 23439366 DOI: 10.4161/rna.24022] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The CRISPR-Cas (clustered regularly interspaced short palindromic repeats, CRISPR-associated genes) is an adaptive immunity system in bacteria and archaea that functions via a distinct self-non-self recognition mechanism that is partially analogous to the mechanism of eukaryotic RNA interference (RNAi). The CRISPR-Cas system incorporates fragments of virus or plasmid DNA into the CRISPR repeat cassettes and employs the processed transcripts of these spacers as guide RNAs to cleave the cognate foreign DNA or RNA. The Cas proteins, however, are not homologous to the proteins involved in RNAi and comprise numerous, highly diverged families. The majority of the Cas proteins contain diverse variants of the RNA recognition motif (RRM), a widespread RNA-binding domain. Despite the fast evolution that is typical of the cas genes, the presence of diverse versions of the RRM in most Cas proteins provides for a simple scenario for the evolution of the three distinct types of CRISPR-cas systems. In addition to several proteins that are directly implicated in the immune response, the cas genes encode a variety of proteins that are homologous to prokaryotic toxins that typically possess nuclease activity. The predicted toxins associated with CRISPR-Cas systems include the essential Cas2 protein, proteins of COG1517 that, in addition to a ligand-binding domain and a helix-turn-helix domain, typically contain different nuclease domains and several other predicted nucleases. The tight association of the CRISPR-Cas immunity systems with predicted toxins that, upon activation, would induce dormancy or cell death suggests that adaptive immunity and dormancy/suicide response are functionally coupled. Such coupling could manifest in the persistence state being induced and potentially providing conditions for more effective action of the immune system or in cell death being triggered when immunity fails.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, NLM, National Institutes of Health, Bethesda, MD, USA.
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17
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Genome sequence of Halorubrum sp. strain T3, an extremely halophilic archaeon harboring a virus-like element. J Bacteriol 2013; 194:6608-9. [PMID: 23144373 DOI: 10.1128/jb.01528-12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Halorubrum sp. strain T3, harboring a virus-like element, was isolated from a sample collected from a solar saltern in Yunnan, China. Several strains of Halorubrum pleomorphic viruses were reported in this genus recently; however, the virus-host interaction in haloarchaea remains unclear. To explore this issue, here we present the genome sequence of Halorubrum sp. strain T3 (3,168,011 bp, 68.48% G+C content).
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