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Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus

CRISPR-Cas (clustered regularly interspaced short palindromic repeat [CRISPR]-CRISPR-associated protein [Cas]) systems can provide protection against invading genetic elements by using CRISPR RNAs (crRNAs) as a guide to locate and degrade the target DNA. CRISPR-Cas systems have been classified into...

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Autores principales: Guan, Jing, Wang, Wanying, Sun, Baolin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5687920/
https://www.ncbi.nlm.nih.gov/pubmed/29152580
http://dx.doi.org/10.1128/mSphere.00403-17
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author Guan, Jing
Wang, Wanying
Sun, Baolin
author_facet Guan, Jing
Wang, Wanying
Sun, Baolin
author_sort Guan, Jing
collection PubMed
description CRISPR-Cas (clustered regularly interspaced short palindromic repeat [CRISPR]-CRISPR-associated protein [Cas]) systems can provide protection against invading genetic elements by using CRISPR RNAs (crRNAs) as a guide to locate and degrade the target DNA. CRISPR-Cas systems have been classified into two classes and five types according to the content of cas genes. Previous studies have indicated that CRISPR-Cas systems can avoid viral infection and block plasmid transfer. Here we show that chromosomal targeting by the Staphylococcus aureus type III-A CRISPR-Cas system can drive large-scale genome deletion and alteration within integrated staphylococcal cassette chromosome mec (SCCmec). The targeting activity of the CRISPR-Cas system is associated with the complementarity between crRNAs and protospacers, and 10- to 13-nucleotide truncations of spacers partially block CRISPR attack and more than 13-nucleotide truncation can fully abolish targeting, suggesting that a minimal length is required to license cleavage. Avoiding base pairings in the upstream region of protospacers is also necessary for CRISPR targeting. Successive trinucleotide complementarity between the 5′ tag of crRNAs and protospacers can disrupt targeting. Our findings reveal that type III-A CRISPR-Cas systems can modulate bacterial genome stability and may serve as a high-efficiency tool for deleting resistance or virulence genes in bacteria. IMPORTANCE Staphylococcus aureus is a pathogen that can cause a wide range of infections in humans. Studies have suggested that CRISPR-Cas systems can drive the loss of integrated mobile genetic elements (MGEs) by chromosomal targeting. Here we demonstrate that CRISPR-mediated cleavage contributes to the partial deletion of integrated SCCmec in methicillin-resistant S. aureus (MRSA), which provides a strategy for the treatment of MRSA infections. The spacer within artificial CRISPR arrays should contain more than 25 nucleotides for immunity, and consecutive trinucleotide pairings between a selected target and the 5′ tag of crRNA can block targeting. These findings add to our understanding of the molecular mechanisms of the type III-A CRISPR-Cas system and provide a novel strategy for the exploitation of engineered CRISPR immunity against integrated MGEs in bacteria for clinical and industrial applications.
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spelling pubmed-56879202017-11-17 Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus Guan, Jing Wang, Wanying Sun, Baolin mSphere Research Article CRISPR-Cas (clustered regularly interspaced short palindromic repeat [CRISPR]-CRISPR-associated protein [Cas]) systems can provide protection against invading genetic elements by using CRISPR RNAs (crRNAs) as a guide to locate and degrade the target DNA. CRISPR-Cas systems have been classified into two classes and five types according to the content of cas genes. Previous studies have indicated that CRISPR-Cas systems can avoid viral infection and block plasmid transfer. Here we show that chromosomal targeting by the Staphylococcus aureus type III-A CRISPR-Cas system can drive large-scale genome deletion and alteration within integrated staphylococcal cassette chromosome mec (SCCmec). The targeting activity of the CRISPR-Cas system is associated with the complementarity between crRNAs and protospacers, and 10- to 13-nucleotide truncations of spacers partially block CRISPR attack and more than 13-nucleotide truncation can fully abolish targeting, suggesting that a minimal length is required to license cleavage. Avoiding base pairings in the upstream region of protospacers is also necessary for CRISPR targeting. Successive trinucleotide complementarity between the 5′ tag of crRNAs and protospacers can disrupt targeting. Our findings reveal that type III-A CRISPR-Cas systems can modulate bacterial genome stability and may serve as a high-efficiency tool for deleting resistance or virulence genes in bacteria. IMPORTANCE Staphylococcus aureus is a pathogen that can cause a wide range of infections in humans. Studies have suggested that CRISPR-Cas systems can drive the loss of integrated mobile genetic elements (MGEs) by chromosomal targeting. Here we demonstrate that CRISPR-mediated cleavage contributes to the partial deletion of integrated SCCmec in methicillin-resistant S. aureus (MRSA), which provides a strategy for the treatment of MRSA infections. The spacer within artificial CRISPR arrays should contain more than 25 nucleotides for immunity, and consecutive trinucleotide pairings between a selected target and the 5′ tag of crRNA can block targeting. These findings add to our understanding of the molecular mechanisms of the type III-A CRISPR-Cas system and provide a novel strategy for the exploitation of engineered CRISPR immunity against integrated MGEs in bacteria for clinical and industrial applications. American Society for Microbiology 2017-11-15 /pmc/articles/PMC5687920/ /pubmed/29152580 http://dx.doi.org/10.1128/mSphere.00403-17 Text en Copyright © 2017 Guan et al. https://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Research Article
Guan, Jing
Wang, Wanying
Sun, Baolin
Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title_full Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title_fullStr Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title_full_unstemmed Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title_short Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in Staphylococcus aureus
title_sort chromosomal targeting by the type iii-a crispr-cas system can reshape genomes in staphylococcus aureus
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5687920/
https://www.ncbi.nlm.nih.gov/pubmed/29152580
http://dx.doi.org/10.1128/mSphere.00403-17
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