scholarly journals Genome editing in plants using CRISPR type I-D nuclease

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Keishi Osakabe ◽  
Naoki Wada ◽  
Tomoko Miyaji ◽  
Emi Murakami ◽  
Kazuya Marui ◽  
...  

Abstract Genome editing in plants has advanced greatly by applying the clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas system, especially CRISPR-Cas9. However, CRISPR type I—the most abundant CRISPR system in bacteria—has not been exploited for plant genome modification. In type I CRISPR-Cas systems, e.g., type I-E, Cas3 nucleases degrade the target DNA in mammals. Here, we present a type I-D (TiD) CRISPR-Cas genome editing system in plants. TiD lacks the Cas3 nuclease domain; instead, Cas10d is the functional nuclease in vivo. TiD was active in targeted mutagenesis of tomato genomic DNA. The mutations generated by TiD differed from those of CRISPR/Cas9; both bi-directional long-range deletions and short indels mutations were detected in tomato cells. Furthermore, TiD can be used to efficiently generate bi-allelic mutant plants in the first generation. These findings indicate that TiD is a unique CRISPR system that can be used for genome engineering in plants.

Author(s):  
Keishi Osakabe ◽  
Naoki Wada ◽  
Emi Murakami ◽  
Yuriko Osakabe

SUMMARYAdoption of the CRISPR-Cas system has revolutionized genome engineering in recent years; however, application of genome editing with CRISPR type I—the most abundant CRISPR system in bacteria—has been less developed. Type I systems in which Cas3 nuclease degrades the target DNA are known; in contrast, for the sub-type CRISPR type I-D (TiD), which lacks a typical Cas3 nuclease in its cascade, the mechanism of target DNA degradation remains unknown. Here, we found that Cas10d—a nuclease in TiD—is multi-functional in PAM recognition, stabilization and target DNA degradation. TiD can be used for targeted mutagenesis of genomic DNA in human cells, directing both bi-directional long-range deletions and short insertions/deletions. TiD off-target effects, which were dependent on the mismatch position in the protospacer of TiD, were also identified. Our findings suggest TiD as a unique effector pathway in CRISPR that can be repurposed for genome engineering in eukaryotic cells.


2018 ◽  
Author(s):  
Raed Ibraheim ◽  
Chun-Qing Song ◽  
Aamir Mir ◽  
Nadia Amrani ◽  
Wen Xue ◽  
...  

AbstractClustered, regularly interspaced, short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) have recently opened a new avenue for gene therapy. Cas9 nuclease guided by a single-guide RNA (sgRNA) has been extensively used for genome editing. Currently, three Cas9 orthologs have been adapted for in vivo genome engineering applications: SpyCas9, SauCas9 and CjeCas9. However, additional in vivo editing platforms are needed, in part to enable a greater range of sequences to be accessed via viral vectors, especially those in which Cas9 and sgRNA are combined into a single vector genome. Here, we present an additional in vivo editing platform using Neisseria meningitidis Cas9 (NmeCas9). NmeCas9 is compact, edits with high accuracy, and possesses a distinct PAM, making it an excellent candidate for safe gene therapy applications. We find that NmeCas9 can be used to target the Pcsk9 and Hpd genes in mice. Using tail vein hydrodynamic-based delivery of NmeCas9 plasmid to target the Hpd gene, we successfully reprogrammed the tyrosine degradation pathway in Hereditary Tyrosinemia Type I mice. More importantly, we delivered NmeCas9 with its single-guide RNA in a single recombinant adeno-associated vector (rAAV) to target Pcsk9, resulting in lower cholesterol levels in mice. This all-in-one vector yielded >35% gene modification after two weeks of vector administration, with minimal off-target cleavage in vivo. Our findings indicate that NmeCas9 can facilitate future efforts to correct disease-causing mutations by expanding the targeting scope of RNA-guided nucleases.


2019 ◽  
Vol 20 (16) ◽  
pp. 4045 ◽  
Author(s):  
Ali Razzaq ◽  
Fozia Saleem ◽  
Mehak Kanwal ◽  
Ghulam Mustafa ◽  
Sumaira Yousaf ◽  
...  

Increasing agricultural productivity via modern breeding strategies is of prime interest to attain global food security. An array of biotic and abiotic stressors affect productivity as well as the quality of crop plants, and it is a primary need to develop crops with improved adaptability, high productivity, and resilience against these biotic/abiotic stressors. Conventional approaches to genetic engineering involve tedious procedures. State-of-the-art OMICS approaches reinforced with next-generation sequencing and the latest developments in genome editing tools have paved the way for targeted mutagenesis, opening new horizons for precise genome engineering. Various genome editing tools such as transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs), and meganucleases (MNs) have enabled plant scientists to manipulate desired genes in crop plants. However, these approaches are expensive and laborious involving complex procedures for successful editing. Conversely, CRISPR/Cas9 is an entrancing, easy-to-design, cost-effective, and versatile tool for precise and efficient plant genome editing. In recent years, the CRISPR/Cas9 system has emerged as a powerful tool for targeted mutagenesis, including single base substitution, multiplex gene editing, gene knockouts, and regulation of gene transcription in plants. Thus, CRISPR/Cas9-based genome editing has demonstrated great potential for crop improvement but regulation of genome-edited crops is still in its infancy. Here, we extensively reviewed the availability of CRISPR/Cas9 genome editing tools for plant biotechnologists to target desired genes and its vast applications in crop breeding research.


2021 ◽  
Vol 22 (14) ◽  
pp. 7456
Author(s):  
Mousa A. Alghuthaymi ◽  
Aftab Ahmad ◽  
Zulqurnain Khan ◽  
Sultan Habibullah Khan ◽  
Farah K. Ahmed ◽  
...  

Rapid developments in the field of plant genome editing using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems necessitate more detailed consideration of the delivery of the CRISPR system into plants. Successful and safe editing of plant genomes is partly based on efficient delivery of the CRISPR system. Along with the use of plasmids and viral vectors as cargo material for genome editing, non-viral vectors have also been considered for delivery purposes. These non-viral vectors can be made of a variety of materials, including inorganic nanoparticles, carbon nanotubes, liposomes, and protein- and peptide-based nanoparticles, as well as nanoscale polymeric materials. They have a decreased immune response, an advantage over viral vectors, and offer additional flexibility in their design, allowing them to be functionalized and targeted to specific sites in a biological system with low cytotoxicity. This review is dedicated to describing the delivery methods of CRISPR system into plants with emphasis on the use of non-viral vectors.


Plant Methods ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Khaoula Belhaj ◽  
Angela Chaparro-Garcia ◽  
Sophien Kamoun ◽  
Vladimir Nekrasov

Author(s):  
Anindya Bandyopadhyay ◽  
Nagesh Kancharla ◽  
vivek javalkote ◽  
santanu dasgupta ◽  
Thomas Brutnell

Global population is predicted to approach 10 billion by 2050, an increase of over 2 billion from today. To meet the demands of growing, geographically and socio-economically diversified nations, we need to diversity and expand agricultural production. This expansion of agricultural productivity will need to occur under increasing biotic, and environmental constraints driven by climate change. Clustered regularly interspaced short palindromic repeats-site directed nucleases (CRISPR-SDN) and similar genome editing technologies will likely be key enablers to meet future agricultural needs. While the application of CRISPR-Cas9 mediated genome editing has led the way, the use of CRISPR-Cas12a is also increasing significantly for genome engineering of plants. The popularity of the CRISPR-Cas12a, the type V (class-II) system, is gaining momentum because of its versatility and simplified features. These include the use of a small guide RNA devoid of trans-activating crispr RNA (tracrRNA), targeting of T-rich regions of the genome where Cas9 is not suitable for use, RNA processing capability facilitating simpler multiplexing, and its ability to generate double strand breaks (DSB) with staggered ends. Many monocot and dicot species have been successfully edited using this Cas12a system and further research is ongoing to improve its efficiency in plants, including improving the temperature stability of the Cas12a enzyme, identifying new variants of Cas12a or synthetically producing Cas12a with flexible PAM sequences. In this review we provide a comparative survey of CRISPR-Cas12a and Cas9, and provide a perspective on applications of CRISPR-Cas12 in agriculture.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1862-1862
Author(s):  
Gregory J. Cost ◽  
Morayma Temoche-Diaz ◽  
Janet Mei ◽  
Cristina N. Butterfield ◽  
Christopher T. Brown ◽  
...  

Abstract RNA guided CRISPR genome editing systems can make specific changes to the genomes of mammalian cells and have the potential to treat a range of diseases including those that can be addressed by editing hepatocytes. Attempts to edit the liver in vivo have relied almost exclusively on the Cas9 nucleases derived from the bacteria S treptococcus pyogenes or Staphylococcus aureus to which humans are commonly exposed. Pre-existing immunity to both these proteins has been reported in humans which raises concerns about their in vivo application. In silico analysis of a large metagenomics database followed by testing in mammalian cells in culture identified MG29-1, a novel CRISPR system which is a member of the Type V family but exhibits only 41 % amino acid identity to Francisella tularensis Cas12a/cpf1. MG29-1 is a 1280 amino acid RNA programmable nuclease that utilizes a single guide RNA comprised of a 22 nucleotide (nt) constant region and a 20 to 25 nt spacer, recognizes the PAM KTTN (predicted frequency 1 in 16 bp) and generates staggered cuts. MG29-1 was derived from a sample taken from a hydrothermal vent and it is therefore unlikely that humans will have developed pre-existing immunity to this protein. A screen for sgRNA targeting serum albumin in the mouse liver cell line Hepa1-6 identified 6 guides that generated more than 80% INDELS. The MG29-1 system was optimized for in vivo delivery by screening chemical modifications to the guide that improve stability in mammalian cell lysates while retaining or improving editing activity. Two lead guide chemistries were evaluated in mice using MG29-1 mRNA and sgRNA packaged in lipid nanoparticles (LNP). Three days after a single IV administration on-target editing was evaluated in the liver by Sanger sequencing. The sgRNA that was the most stable in the in vitro assay generated INDELS that ranged from 20 to 25% while a sgRNA with lower in vitro stability failed to generate detectable INDELs. The short sgRNA and small protein size compared to spCas9 makes MG29-1 an attractive alternative to spCas9 for in vivo editing applications. Evaluation of the potential of MG29-1 to perform gene knockouts and gene additions via non-homologous end joining is ongoing. Disclosures No relevant conflicts of interest to declare.


2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Patricia L. Baker ◽  
Gregory S. Orf ◽  
Kimberly Kevershan ◽  
Michael E. Pyne ◽  
Taner Bicer ◽  
...  

ABSTRACT In Heliobacterium modesticaldum, as in many Firmicutes, deleting genes by homologous recombination using standard techniques has been extremely difficult. The cells tend to integrate the introduced plasmid into the chromosome by a single recombination event rather than perform the double recombination required to replace the targeted locus. Transformation with a vector containing only a homologous recombination template for replacement of the photochemical reaction center gene pshA produced colonies with multiple genotypes, rather than a clean gene replacement. To address this issue, we required an additional means of selection to force a clean gene replacement. In this study, we report the genetic structure of the type I-A and I-E CRISPR-Cas systems from H. modesticaldum, as well as methods to leverage the type I-A system for genome editing. In silico analysis of the CRISPR spacers revealed a potential consensus protospacer adjacent motif (PAM) required for Cas3 recognition, which was then tested using an in vivo interference assay. Introduction of a homologous recombination plasmid that carried a miniature CRISPR array targeting sequences in pshA (downstream of a naturally occurring PAM sequence) produced nonphototrophic transformants with clean replacements of the pshA gene with ∼80% efficiency. Mutants were confirmed by PCR, sequencing, optical spectroscopy, and growth characteristics. This methodology should be applicable to any genetic locus in the H. modesticaldum genome. IMPORTANCE The heliobacteria are the only phototrophic members of the largely Gram-positive phylum Firmicutes, which contains medically and industrially important members, such as Clostridium difficile and Clostridium acetobutylicum. Heliobacteria are of interest in the study of photosynthesis because their photosynthetic system is unique and the simplest known. Since their discovery in the early 1980s, work on the heliobacteria has been hindered by the lack of a genetic transformation system. The problem of introducing foreign DNA into these bacteria has been recently rectified by our group; however, issues still remained for efficient genome editing. The significance of this work is that we have characterized the endogenous type I CRISPR-Cas system in the heliobacteria and leveraged it to assist in genome editing. Using the CRISPR-Cas system allowed us to isolate transformants with precise replacement of the pshA gene encoding the main subunit of the photochemical reaction center.


2020 ◽  
Author(s):  
Clinton Gabel ◽  
Zhuang Li ◽  
Heng Zhang ◽  
Leifu Chang

Abstract CRISPR–Cas systems are adaptive immune systems in bacteria and archaea to defend against mobile genetic elements (MGEs) and have been repurposed as genome editing tools. Anti-CRISPR (Acr) proteins are produced by MGEs to counteract CRISPR–Cas systems and can be used to regulate genome editing by CRISPR techniques. Here, we report the cryo-EM structures of three type I-F Acr proteins, AcrIF4, AcrIF7 and AcrIF14, bound to the type I-F CRISPR–Cas surveillance complex (the Csy complex) from Pseudomonas aeruginosa. AcrIF4 binds to an unprecedented site on the C-terminal helical bundle of Cas8f subunit, precluding conformational changes required for activation of the Csy complex. AcrIF7 mimics the PAM duplex of target DNA and is bound to the N-terminal DNA vise of Cas8f. Two copies of AcrIF14 bind to the thumb domains of Cas7.4f and Cas7.6f, preventing hybridization between target DNA and the crRNA. Our results reveal structural detail of three AcrIF proteins, each binding to a different site on the Csy complex for inhibiting degradation of MGEs.


Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 467
Author(s):  
Min Hao ◽  
Zhaoguan Wang ◽  
Hongyan Qiao ◽  
Peng Yin ◽  
Jianjun Qiao ◽  
...  

As a key element of genome editing, donor DNA introduces the desired exogenous sequence while working with other crucial machinery such as CRISPR-Cas or recombinases. However, current methods for the delivery of donor DNA into cells are both inefficient and complicated. Here, we developed a new methodology that utilizes rolling circle replication and Cas9 mediated (RC-Cas-mediated) in vivo single strand DNA (ssDNA) synthesis. A single-gene rolling circle DNA replication system from Gram-negative bacteria was engineered to produce circular ssDNA from a Gram-positive parent plasmid at a designed sequence in Escherichia coli. Furthermore, it was demonstrated that the desired linear ssDNA fragment could be cut out using CRISPR-associated protein 9 (CRISPR-Cas9) nuclease and combined with lambda Red recombinase as donor for precise genome engineering. Various donor ssDNA fragments from hundreds to thousands of nucleotides in length were synthesized in E. coli cells, allowing successive genome editing in growing cells. We hope that this RC-Cas-mediated in vivo ssDNA on-site synthesis system will be widely adopted as a useful new tool for dynamic genome editing.


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