Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>

ABSTRACT 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 classif...

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Autores principales:	Jing Guan, Wanying Wang, Baolin Sun
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	CRISPR-Cas system Staphylococcus aureus chromosomal targeting mobile genetic element staphylococcal cassette chromosome mec Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/09d83279654f43daad9001425237ea3d
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spelling	oai:doaj.org-article:09d83279654f43daad9001425237ea3d2021-11-15T15:21:51ZChromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>10.1128/mSphere.00403-172379-5042https://doaj.org/article/09d83279654f43daad9001425237ea3d2017-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00403-17https://doaj.org/toc/2379-5042ABSTRACT 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.Jing GuanWanying WangBaolin SunAmerican Society for MicrobiologyarticleCRISPR-Cas systemStaphylococcus aureuschromosomal targetingmobile genetic elementstaphylococcal cassette chromosome mecMicrobiologyQR1-502ENmSphere, Vol 2, Iss 6 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	CRISPR-Cas system Staphylococcus aureus chromosomal targeting mobile genetic element staphylococcal cassette chromosome mec Microbiology QR1-502
spellingShingle	CRISPR-Cas system Staphylococcus aureus chromosomal targeting mobile genetic element staphylococcal cassette chromosome mec Microbiology QR1-502 Jing Guan Wanying Wang Baolin Sun Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
description	ABSTRACT 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.
format	article
author	Jing Guan Wanying Wang Baolin Sun
author_facet	Jing Guan Wanying Wang Baolin Sun
author_sort	Jing Guan
title	Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
title_short	Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
title_full	Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
title_fullStr	Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
title_full_unstemmed	Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>
title_sort	chromosomal targeting by the type iii-a crispr-cas system can reshape genomes in <named-content content-type="genus-species">staphylococcus aureus</named-content>
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/09d83279654f43daad9001425237ea3d
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Chromosomal Targeting by the Type III-A CRISPR-Cas System Can Reshape Genomes in <named-content content-type="genus-species">Staphylococcus aureus</named-content>

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