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Open AccessJournal ArticleDOI

Small CRISPR RNAs guide antiviral defense in prokaryotes

TLDR
The results demonstrate that the formation of mature guide RNAs by the CRISPR RNA endonuclease subunit of Cascade is a mechanistic requirement for antiviral defense.
Abstract
Prokaryotes acquire virus resistance by integrating short fragments of viral nucleic acid into clusters of regularly interspaced short palindromic repeats (CRISPRs). Here we show how virus-derived sequences contained in CRISPRs are used by CRISPR-associated (Cas) proteins from the host to mediate an antiviral response that counteracts infection. After transcription of the CRISPR, a complex of Cas proteins termed Cascade cleaves a CRISPR RNA precursor in each repeat and retains the cleavage products containing the virus-derived sequence. Assisted by the helicase Cas3, these mature CRISPR RNAs then serve as small guide RNAs that enable Cascade to interfere with virus proliferation. Our results demonstrate that the formation of mature guide RNAs by the CRISPR RNA endonuclease subunit of Cascade is a mechanistic requirement for antiviral defense.

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Journal ArticleDOI

A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity.

TL;DR: This study reveals a family of endonucleases that use dual-RNAs for site-specific DNA cleavage and highlights the potential to exploit the system for RNA-programmable genome editing.
Journal ArticleDOI

Multiplex Genome Engineering Using CRISPR/Cas Systems

TL;DR: The type II prokaryotic CRISPR (clustered regularly interspaced short palindromic repeats)/Cas adaptive immune system has been shown to facilitate RNA-guided site-specific DNA cleavage as discussed by the authors.

Multiplex Genome Engineering Using CRISPR/Cas Systems

TL;DR: Two different type II CRISPR/Cas systems are engineered and it is demonstrated that Cas9 nucleases can be directed by short RNAs to induce precise cleavage at endogenous genomic loci in human and mouse cells, demonstrating easy programmability and wide applicability of the RNA-guided nuclease technology.
Journal ArticleDOI

Genome engineering using the CRISPR-Cas9 system

TL;DR: A set of tools for Cas9-mediated genome editing via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, as well as generation of modified cell lines for downstream functional studies are described.
Journal ArticleDOI

The new frontier of genome engineering with CRISPR-Cas9

TL;DR: The power of the CRISPR-Cas9 technology to systematically analyze gene functions in mammalian cells, study genomic rearrangements and the progression of cancers or other diseases, and potentially correct genetic mutations responsible for inherited disorders is illustrated.
References
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Journal ArticleDOI

CRISPR provides acquired resistance against viruses in prokaryotes

TL;DR: It is found that, after viral challenge, bacteria integrated new spacers derived from phage genomic sequences, and CRISPR provided resistance against phages, and resistance specificity is determined by spacer-phage sequence similarity.
Journal ArticleDOI

Intervening Sequences of Regularly Spaced Prokaryotic Repeats Derive from Foreign Genetic Elements

TL;DR: It is shown that CRISPR spacers derive from preexisting sequences, either chromosomal or within transmissible genetic elements such as bacteriophages and conjugative plasmids, implying a relationship betweenCRISPR and immunity against targeted DNA.
Journal ArticleDOI

Identification of genes that are associated with DNA repeats in prokaryotes.

TL;DR: A novel family of repetitive DNA sequences that is present among both domains of the prokaryotes but absent from eukaryotes or viruses is studied, characterized by direct repeats, varying in size from 21 to 37 bp, interspaced by similarly sized non‐repetitive sequences.
Journal ArticleDOI

Clustered regularly interspaced short palindrome repeats (CRISPRs) have spacers of extrachromosomal origin.

TL;DR: The authors suggest that the spacer elements are the traces of past invasions by extrachromosomal elements, and hypothesize that they provide the cell immunity against phage infection, and more generally foreign DNA expression, by coding an anti-sense RNA.
Journal ArticleDOI

Phage response to CRISPR-encoded resistance in Streptococcus thermophilus.

TL;DR: It is shown through the analyses of 20 mutant phages that virulent phages are rapidly evolving through single nucleotide mutations as well as deletions, in response to CRISPR1.
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Trending Questions (1)
What RNA is used in Crispr?

Our results demonstrate that the formation of mature guide RNAs by the CRISPR RNA endonuclease subunit of Cascade is a mechanistic requirement for antiviral defense.