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The evolution of a counter-defense mechanism in a virus constrains its host range

Bacteria use diverse immunity mechanisms to defend themselves against their viral predators, bacteriophages. In turn, phages can acquire counter-defense systems, but it remains unclear how such mechanisms arise and what factors constrain viral evolution. Here, we experimentally evolved T4 phage to o...

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Autores principales: Srikant, Sriram, Guegler, Chantal K, Laub, Michael T
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9391042/
https://www.ncbi.nlm.nih.gov/pubmed/35924892
http://dx.doi.org/10.7554/eLife.79549
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author Srikant, Sriram
Guegler, Chantal K
Laub, Michael T
author_facet Srikant, Sriram
Guegler, Chantal K
Laub, Michael T
author_sort Srikant, Sriram
collection PubMed
description Bacteria use diverse immunity mechanisms to defend themselves against their viral predators, bacteriophages. In turn, phages can acquire counter-defense systems, but it remains unclear how such mechanisms arise and what factors constrain viral evolution. Here, we experimentally evolved T4 phage to overcome a phage-defensive toxin-antitoxin system, toxIN, in Escherichia coli. Through recombination, T4 rapidly acquires segmental amplifications of a previously uncharacterized gene, now named tifA, encoding an inhibitor of the toxin, ToxN. These amplifications subsequently drive large deletions elsewhere in T4’s genome to maintain a genome size compatible with capsid packaging. The deleted regions include accessory genes that help T4 overcome defense systems in alternative hosts. Thus, our results reveal a trade-off in viral evolution; the emergence of one counter-defense mechanism can lead to loss of other such mechanisms, thereby constraining host range. We propose that the accessory genomes of viruses reflect the integrated evolutionary history of the hosts they infected.
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spelling pubmed-93910422022-08-20 The evolution of a counter-defense mechanism in a virus constrains its host range Srikant, Sriram Guegler, Chantal K Laub, Michael T eLife Evolutionary Biology Bacteria use diverse immunity mechanisms to defend themselves against their viral predators, bacteriophages. In turn, phages can acquire counter-defense systems, but it remains unclear how such mechanisms arise and what factors constrain viral evolution. Here, we experimentally evolved T4 phage to overcome a phage-defensive toxin-antitoxin system, toxIN, in Escherichia coli. Through recombination, T4 rapidly acquires segmental amplifications of a previously uncharacterized gene, now named tifA, encoding an inhibitor of the toxin, ToxN. These amplifications subsequently drive large deletions elsewhere in T4’s genome to maintain a genome size compatible with capsid packaging. The deleted regions include accessory genes that help T4 overcome defense systems in alternative hosts. Thus, our results reveal a trade-off in viral evolution; the emergence of one counter-defense mechanism can lead to loss of other such mechanisms, thereby constraining host range. We propose that the accessory genomes of viruses reflect the integrated evolutionary history of the hosts they infected. eLife Sciences Publications, Ltd 2022-08-04 /pmc/articles/PMC9391042/ /pubmed/35924892 http://dx.doi.org/10.7554/eLife.79549 Text en © 2022, Srikant, Guegler et al https://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Evolutionary Biology
Srikant, Sriram
Guegler, Chantal K
Laub, Michael T
The evolution of a counter-defense mechanism in a virus constrains its host range
title The evolution of a counter-defense mechanism in a virus constrains its host range
title_full The evolution of a counter-defense mechanism in a virus constrains its host range
title_fullStr The evolution of a counter-defense mechanism in a virus constrains its host range
title_full_unstemmed The evolution of a counter-defense mechanism in a virus constrains its host range
title_short The evolution of a counter-defense mechanism in a virus constrains its host range
title_sort evolution of a counter-defense mechanism in a virus constrains its host range
topic Evolutionary Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9391042/
https://www.ncbi.nlm.nih.gov/pubmed/35924892
http://dx.doi.org/10.7554/eLife.79549
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