Metagenomes
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PROVIDER: PRJNA349044 | ENA |
REPOSITORIES: ENA
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Project description:The development of CRISPR-Cas systems for targeting DNA and RNA in diverse organisms has transformed biotechnology and biological research. Moreover, the CRISPR revolution has highlighted bacterial adaptive immune systems as a rich and largely unexplored frontier for discovery of new genome engineering technologies. In particular, the class 2 CRISPR-Cas systems, which use single RNA-guided DNA-targeting nucleases such as Cas9, have been widely applied for targeting DNA sequences in eukaryotic genomes. Here, we report DNA-targeting and transcriptional control with class I CRISPR-Cas systems. Specifically, we repurpose the effector complex from type I variants of class 1 CRISPR-Cas systems, the most prevalent CRISPR loci in nature, that target DNA via a multi-component RNA-guided complex termed Cascade. We validate Cascade expression, complex formation, and nuclear localization in human cells and demonstrate programmable CRISPR RNA (crRNA)-mediated targeting of specific loci in the human genome. By tethering transactivation domains to Cascade, we modulate the expression of targeted chromosomal genes in both human cells and plants. This study expands the toolbox for engineering eukaryotic genomes and establishes Cascade as a novel CRISPR-based technology for targeted eukaryotic gene regulation.
2019-06-26 | GSE114858 | GEO
Project description:The development of CRISPR-Cas systems for targeting DNA and RNA in diverse organisms has transformed biotechnology and biological research. Moreover, the CRISPR revolution has highlighted bacterial adaptive immune systems as a rich and largely unexplored frontier for discovery of new genome engineering technologies. In particular, the class 2 CRISPR-Cas systems, which use single RNA-guided DNA-targeting nucleases such as Cas9, have been widely applied for targeting DNA sequences in eukaryotic genomes. Here, we report DNA-targeting and transcriptional control with class I CRISPR-Cas systems. Specifically, we repurpose the effector complex from type I variants of class 1 CRISPR-Cas systems, the most prevalent CRISPR loci in nature, that target DNA via a multi-component RNA-guided complex termed Cascade. We validate Cascade expression, complex formation, and nuclear localization in human cells and demonstrate programmable CRISPR RNA (crRNA)-mediated targeting of specific loci in the human genome. By tethering transactivation domains to Cascade, we modulate the expression of targeted chromosomal genes in both human cells and plants. This study expands the toolbox for engineering eukaryotic genomes and establishes Cascade as a novel CRISPR-based technology for targeted eukaryotic gene regulation.
2019-06-26 | GSE114857 | GEO
Project description:CRISPR-Cas immune systems function to defend prokaryotes against potentially harmful mobile genetic elements including viruses and plasmids. The multiple CRISPR-Cas systems (Types I, II, III) each recognize and target destruction of foreign invader nucleic acids via structurally and functionally diverse effector complexes (crRNPs). CRISPR-Cas effector complexes are comprised of CRISPR RNAs (crRNAs) that contain sequences homologous to the invading nucleic acids and Cas proteins specific to each immune system type. We have previously characterized a crRNP in Pyrococcus furiosus (Pfu) that contains Cmr proteins (Type III-B) associated with one of two primary size forms of crRNAs and functions through homology-dependent cleavage of target RNAs. In the current study, we have isolated and characterized two additional native Pfu CRISPR-Cas complexes containing either Csa (Type I-A) or Cst (Type I-G) proteins and distinct profiles of associated crRNAs. For each complex, the Cas proteins were identified by tandem mass spectrometry and immunoblotting and the crRNAs by RNA deep sequencing and Northern blot analysis. The crRNAs associated with both the Csa and Cst complexes originate from each of seven total CRISPR loci and contain identical 5’ ends (8-nt CRISPR RNA repeat-derived 5’ tag sequences) but heterogeneous 3’ ends (containing variable amounts of downstream repeat sequences). These crRNA forms are distinct from Cmr-associated crRNAs, indicating different 3’ end processing pathways following primary cleavage of common pre-crRNAs. We predict that the newly identified Pfu Type I-A (Csa) and Type I-G (Cst)-containing crRNPs, like other previously characterized Type I CRISPR-Cas effector complexes, each function by carrying out crRNA-guided DNA targeting of invading mobile genetic elements. Taken together, our in-depth characterization of the three isolated native complexes provides clear evidence for three compositionally distinct crRNPs containing either Cmr, Csa, or Cst Cas proteins that together make up an impressive arsenal of CRISPR-Cas defense for a single organism. 4 Samples: Protein-associated small RNAs
2015-07-10 | E-GEOD-65781 | biostudies-arrayexpress
Project description:The CRISPR-Cas universe continues to expand. The type II CRISPR-Cas system from Streptococcus pyogenes (SpyCas9) is most widely used for genome editing due to its high efficiency in cells and organisms. However, concentrating on a single CRISPR-Cas system imposes limits on target selection and multiplexed genome engineering. We hypothesized that CRISPR-Cas systems originating from different bacterial species could operate simultaneously and independently due to their distinct single-guide RNAs (sgRNAs) or CRISPR-RNAs (crRNAs), and protospacer adjacent motifs (PAMs). Additionally, we hypothesized that CRISPR-Cas activity in zebrafish could be regulated through the expression of inhibitory anti-CRISPR (Acr) proteins. Here, we use a simple mutagenesis approach to demonstrate that CRISPR-Cas systems from Streptococcus pyogenes (SpyCas9), Streptococcus aureus (SauCas9), Lachnospiraceae bacterium (LbaCas12a, previously known as LbCpf1), Acidaminococcus sp. (AspCas12a, previously known as AsCpf1) and Neisseria meningitidis (Nme2Cas9) are orthogonal systems capable of operating simultaneously in zebrafish. We implemented multichannel CRISPR recording using up to three CRISPR systems, and show that LbaCas12a may provide superior information density compared to previous methods. We also demonstrate that type II Acrs (anti-CRISPRs) are effective inhibitors of SpyCas9 in zebrafish. These results indicate that at least five CRISPR-Cas systems and two anti-CRISPR proteins are functional in zebrafish embryos. These orthogonal CRISPR-Cas systems and Acr proteins will enable combinatorial and intersectional strategies for spatiotemporal control of genome editing and genetic recording in animals.
2021-10-25 | GSE186338 | GEO
Project description:Bacteria protect themselves from infection by bacteriophages (phages) using different defence systems, such as CRISPR-Cas. Although CRISPR-Cas provides phage resistance, fitness costs are incurred, such as through autoimmunity. CRISPR-Cas regulation can optimise defence and minimise these costs. We recently developed a genome-wide functional genomics approach (SorTn-seq) for high-throughput discovery of regulators of bacterial gene expression. Here, we applied SorTn-seq to identify loci influencing expression of the two type III-A Serratia CRISPR arrays. Multiple genes affected CRISPR expression, including those involved in outer membrane and lipopolysaccharide synthesis. By comparing loci affecting type III CRISPR arrays and cas operon expression, we identified PigU (LrhA) as a repressor that co-ordinately controls both arrays and cas genes. By repressing type III-A CRISPR-Cas expression, PigU shuts off CRISPR-Cas interference against plasmids and phages. PigU also represses interference and CRISPR adaptation by the type I-F system, which is also present in Serratia. RNA sequencing demonstrated that PigU is a global regulator that controls secondary metabolite production and motility, in addition to CRISPR-Cas immunity. Increased PigU also resulted in elevated expression of three Serratia prophages, indicating their likely induction upon sensing PigU-induced cellular changes. In summary, PigU is a major regulator of CRISPR-Cas immunity in Serratia.
2023-11-20 | GSE243790 | GEO
Project description:In this work, we analyzed recognized PAM sequences from four CRISPR-Cas systems: E. coli I-E, B. halodurans I-C, S. thermophilus CR1 II-A, and F. novicida V. Cells containing functional PAMs were sorted using FACS and subsequently sequenced. Ranking of recognized PAMs from a positive screen
2016-02-17 | E-GEOD-75718 | biostudies-arrayexpress
Project description:We report the PAMs of diverse type I-E CRISPR- Cas systems and the type I-C and the type I-F1 CRISPR-Cas systems from Xanthomonas albilineans. Furthermore, we report PAMs of two type I-B CRISPR transposons (CASTs) and the Vibrio cholerae type I-F CAST. For identification of the PAMs, we used a cell-free TXTL-based PAM screen we named PAM-DETECT. By adding a 5N randomized PAM library and plasmids encoding for Cascade genes and gRNAs, recognized PAMs were bound by Cascade and protected from cleavage by a restriction enzyme that has it's recognition site within the target region. By amplifying the non-cleaved target plasmid, we used next-generation sequencing to analyze the enrichment of functional PAMs of the studied CRISPR-Cas systems. We additionally assessed the insertion sites of crRNA-dependent and crRNA-independent transposition of the Rippkaea orientalis type I-B CAST in TXTL and E. coli.
2022-02-24 | GSE179614 | GEO
Project description:Cornelia de Lange syndrome (CdLS) is an autosomal dominant disease mainly caused by mutations in the Nipped-B-like protein (NIPBL) gene resulting in the alteration of the cohesin pathway. Here, we generated human induced pluripotent stem cells (hiPSCs) from a CdLS patient carrying a mutation in the NIPBL gene, c.5483G>A, and tested CRISPR-Cas based approaches to repair the genetic defect. We applied an efficient and precise method of gene correction through CRISPR-Cas induced homology directed repair (HDR), which allowed the generation of hiPSC clones with regular karyotype and preserved stemness. The efficient and precise gene replacement strategy developed in this study can be extended to the modification of other genomic loci in hiPSCs. Isogenic wild-type and mutated hiPSCs produced with the CRISPR-Cas technology are fundamental CdLS cellular models to study the disease molecular determinants and identifying therapeutic targets.
2023-03-17 | E-MTAB-11604 | biostudies-arrayexpress
Project description:CRISPR-Cas systems store fragments of invader DNA as spacers to recognize and clear those same invaders in the future. Spacers can also be acquired from the host’s genomic DNA, leading to lethal self-targeting. While self-targeting can be circumvented through different mechanisms, natural examples remain poorly explored. Here, we investigate extensive self-targeting by two CRISPR-Cas systems encoding an astonishing 24 self-targeting spacers in the plant pathogen Xanthomonas albilineans. We show, based on transcriptomics analyses, that the native I-C and I-F1 systems are actively expressed and that CRISPR RNAs are properly processed. When expressed in Escherichia coli, each Cascade complex binds its PAM-flanked DNA target to block transcription, while the addition of Cas3 paired with genome targeting induces cell killing. While exploring how X. albilineans survives self-targeting, we predicted putative anti-CRISPR proteins (Acrs) encoded within the bacterium’s genome. Screening of identified candidates with cell-free transcription-translation systems and in E. coli revealed two Acrs, which we named AcrIC11 and AcrIF12Xal, that inhibit Cas3 but not Cascade of the respective system. These findings reveal how a bacterium tolerates extensive self-targeting through two CRISPR-Cas systems and expand the suite of Cas3-inhibiting Acrs.
2023-10-28 | GSE229478 | GEO
Project description:CRISPR-Cas immune systems function to defend prokaryotes against potentially harmful mobile genetic elements including viruses and plasmids. The multiple CRISPR-Cas systems (Types I, II, III) each recognize and target destruction of foreign invader nucleic acids via structurally and functionally diverse effector complexes (crRNPs). CRISPR-Cas effector complexes are comprised of CRISPR RNAs (crRNAs) that contain sequences homologous to the invading nucleic acids and Cas proteins specific to each immune system type. We have previously characterized a crRNP in Pyrococcus furiosus (Pfu) that contains Cmr proteins (Type III-B) associated with one of two primary size forms of crRNAs and functions through homology-dependent cleavage of target RNAs. In the current study, we have isolated and characterized two additional native Pfu CRISPR-Cas complexes containing either Csa (Type I-A) or Cst (Type I-G) proteins and distinct profiles of associated crRNAs. For each complex, the Cas proteins were identified by tandem mass spectrometry and immunoblotting and the crRNAs by RNA deep sequencing and Northern blot analysis. The crRNAs associated with both the Csa and Cst complexes originate from each of seven total CRISPR loci and contain identical 5’ ends (8-nt CRISPR RNA repeat-derived 5’ tag sequences) but heterogeneous 3’ ends (containing variable amounts of downstream repeat sequences). These crRNA forms are distinct from Cmr-associated crRNAs, indicating different 3’ end processing pathways following primary cleavage of common pre-crRNAs. We predict that the newly identified Pfu Type I-A (Csa) and Type I-G (Cst)-containing crRNPs, like other previously characterized Type I CRISPR-Cas effector complexes, each function by carrying out crRNA-guided DNA targeting of invading mobile genetic elements. Taken together, our in-depth characterization of the three isolated native complexes provides clear evidence for three compositionally distinct crRNPs containing either Cmr, Csa, or Cst Cas proteins that together make up an impressive arsenal of CRISPR-Cas defense for a single organism.
2015-07-10 | GSE65781 | GEO