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Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans

CRISPR-Cas is a bacterial immune system that restricts the acquisition of mobile DNA elements. These systems provide immunity against foreign DNA by encoding CRISPR spacers that help target DNA if it re-enters the cell. In this way, CRISPR spacers are a type of molecular tape recorder of foreign DNA...

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Autores principales: Walker, Alejandro R., Shields, Robert C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9522601/
https://www.ncbi.nlm.nih.gov/pubmed/36186424
http://dx.doi.org/10.3389/fgene.2022.997341
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author Walker, Alejandro R.
Shields, Robert C.
author_facet Walker, Alejandro R.
Shields, Robert C.
author_sort Walker, Alejandro R.
collection PubMed
description CRISPR-Cas is a bacterial immune system that restricts the acquisition of mobile DNA elements. These systems provide immunity against foreign DNA by encoding CRISPR spacers that help target DNA if it re-enters the cell. In this way, CRISPR spacers are a type of molecular tape recorder of foreign DNA encountered by the host microorganism. Here, we extracted ∼8,000 CRISPR spacers from a collection of over three hundred Streptococcus mutans genomes. Phage DNA is a major target of S. mutans spacers. S. mutans strains have also generated immunity against mobile DNA elements such as plasmids and integrative and conjugative elements. There may also be considerable immunity generated against bacterial DNA, although the relative contribution of self-targeting versus bona fide intra- or inter-species targeting needs to be investigated further. While there was clear evidence that these systems have acquired immunity against foreign DNA, there appeared to be minimal impact on horizontal gene transfer (HGT) constraints on a species-level. There was little or no impact on genome size, GC content and ‘openness’ of the pangenome when comparing between S. mutans strains with low or high CRISPR spacer loads. In summary, while there is evidence of CRISPR spacer acquisition against self and foreign DNA, CRISPR-Cas does not act as a barrier on the expansion of the S. mutans accessory genome.
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spelling pubmed-95226012022-10-01 Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans Walker, Alejandro R. Shields, Robert C. Front Genet Genetics CRISPR-Cas is a bacterial immune system that restricts the acquisition of mobile DNA elements. These systems provide immunity against foreign DNA by encoding CRISPR spacers that help target DNA if it re-enters the cell. In this way, CRISPR spacers are a type of molecular tape recorder of foreign DNA encountered by the host microorganism. Here, we extracted ∼8,000 CRISPR spacers from a collection of over three hundred Streptococcus mutans genomes. Phage DNA is a major target of S. mutans spacers. S. mutans strains have also generated immunity against mobile DNA elements such as plasmids and integrative and conjugative elements. There may also be considerable immunity generated against bacterial DNA, although the relative contribution of self-targeting versus bona fide intra- or inter-species targeting needs to be investigated further. While there was clear evidence that these systems have acquired immunity against foreign DNA, there appeared to be minimal impact on horizontal gene transfer (HGT) constraints on a species-level. There was little or no impact on genome size, GC content and ‘openness’ of the pangenome when comparing between S. mutans strains with low or high CRISPR spacer loads. In summary, while there is evidence of CRISPR spacer acquisition against self and foreign DNA, CRISPR-Cas does not act as a barrier on the expansion of the S. mutans accessory genome. Frontiers Media S.A. 2022-09-15 /pmc/articles/PMC9522601/ /pubmed/36186424 http://dx.doi.org/10.3389/fgene.2022.997341 Text en Copyright © 2022 Walker and Shields. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Genetics
Walker, Alejandro R.
Shields, Robert C.
Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title_full Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title_fullStr Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title_full_unstemmed Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title_short Investigating CRISPR spacer targets and their impact on genomic diversification of Streptococcus mutans
title_sort investigating crispr spacer targets and their impact on genomic diversification of streptococcus mutans
topic Genetics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9522601/
https://www.ncbi.nlm.nih.gov/pubmed/36186424
http://dx.doi.org/10.3389/fgene.2022.997341
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