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Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back

The Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-CRISPR-associated proteins (Cas) systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas t...

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Autores principales: Koonin, Eugene V., Makarova, Kira S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5737515/
https://www.ncbi.nlm.nih.gov/pubmed/28985291
http://dx.doi.org/10.1093/gbe/evx192
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author Koonin, Eugene V.
Makarova, Kira S.
author_facet Koonin, Eugene V.
Makarova, Kira S.
author_sort Koonin, Eugene V.
collection PubMed
description The Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-CRISPR-associated proteins (Cas) systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas that is responsible for the formation of the immune memory apparently evolved from a Casposon, a self-synthesizing transposon that employs the Cas1 protein as the integrase and might have brought additional cas genes to the emerging immunity loci. Second, a large subset of type III CRISPR-Cas systems recruited a reverse transcriptase from a Group II intron, providing for spacer acquisition from RNA. Third, effector nucleases of Class 2 CRISPR-Cas systems that are responsible for the recognition and cleavage of the target DNA were derived from transposon-encoded TnpB nucleases, most likely, on several independent occasions. Fourth, accessory nucleases in some variants of types I and III toxin and type VI effectors RNases appear to be ultimately derived from toxin nucleases of microbial toxin–antitoxin modules. Fifth, the opposite direction of evolution is manifested in the recruitment of CRISPR-Cas systems by a distinct family of Tn7-like transposons that probably exploit the capacity of CRISPR-Cas to recognize unique DNA sites to facilitate transposition as well as by bacteriophages that employ them to cope with host defense. Additionally, individual Cas proteins, such as the Cas4 nuclease, were recruited by bacteriophages and transposons. The two-sided evolutionary connection between CRISPR-Cas and MGE fits the “guns for hire” paradigm whereby homologous enzymatic machineries, in particular nucleases, are shuttled between MGE and defense systems and are used alternately as means of offense or defense.
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spelling pubmed-57375152018-01-09 Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back Koonin, Eugene V. Makarova, Kira S. Genome Biol Evol Research Article The Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-CRISPR-associated proteins (Cas) systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas that is responsible for the formation of the immune memory apparently evolved from a Casposon, a self-synthesizing transposon that employs the Cas1 protein as the integrase and might have brought additional cas genes to the emerging immunity loci. Second, a large subset of type III CRISPR-Cas systems recruited a reverse transcriptase from a Group II intron, providing for spacer acquisition from RNA. Third, effector nucleases of Class 2 CRISPR-Cas systems that are responsible for the recognition and cleavage of the target DNA were derived from transposon-encoded TnpB nucleases, most likely, on several independent occasions. Fourth, accessory nucleases in some variants of types I and III toxin and type VI effectors RNases appear to be ultimately derived from toxin nucleases of microbial toxin–antitoxin modules. Fifth, the opposite direction of evolution is manifested in the recruitment of CRISPR-Cas systems by a distinct family of Tn7-like transposons that probably exploit the capacity of CRISPR-Cas to recognize unique DNA sites to facilitate transposition as well as by bacteriophages that employ them to cope with host defense. Additionally, individual Cas proteins, such as the Cas4 nuclease, were recruited by bacteriophages and transposons. The two-sided evolutionary connection between CRISPR-Cas and MGE fits the “guns for hire” paradigm whereby homologous enzymatic machineries, in particular nucleases, are shuttled between MGE and defense systems and are used alternately as means of offense or defense. Oxford University Press 2017-09-18 /pmc/articles/PMC5737515/ /pubmed/28985291 http://dx.doi.org/10.1093/gbe/evx192 Text en Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution 2017. This work is written by US Government employees and is in the public domain in the US. http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/ This Open Access article contains public sector information licensed under the Open Government Licence v2.0 (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/)
spellingShingle Research Article
Koonin, Eugene V.
Makarova, Kira S.
Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title_full Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title_fullStr Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title_full_unstemmed Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title_short Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back
title_sort mobile genetic elements and evolution of crispr-cas systems: all the way there and back
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5737515/
https://www.ncbi.nlm.nih.gov/pubmed/28985291
http://dx.doi.org/10.1093/gbe/evx192
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