Mutational spectrum drives the rise of mutator bacteria.

Understanding how mutator strains emerge in bacterial populations is relevant both to evolutionary theory and to reduce the threat they pose in clinical settings. The rise of mutator alleles is understood as a result of their hitchhiking with linked beneficial mutations, although the factors that go...

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Main Authors: Alejandro Couce, Javier R Guelfo, Jesús Blázquez
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2013-01-01
Series:PLoS Genetics
Online Access:https://journals.plos.org/plosgenetics/article/file?id=10.1371/journal.pgen.1003167&type=printable
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author Alejandro Couce
Javier R Guelfo
Jesús Blázquez
author_facet Alejandro Couce
Javier R Guelfo
Jesús Blázquez
author_sort Alejandro Couce
collection DOAJ
description Understanding how mutator strains emerge in bacterial populations is relevant both to evolutionary theory and to reduce the threat they pose in clinical settings. The rise of mutator alleles is understood as a result of their hitchhiking with linked beneficial mutations, although the factors that govern this process remain unclear. A prominent but underappreciated fact is that each mutator allele increases only a specific spectrum of mutational changes. This spectrum has been speculated to alter the distribution of fitness effects of beneficial mutations, potentially affecting hitchhiking. To study this possibility, we analyzed the fitness distribution of beneficial mutations generated from different mutator and wild-type Escherichia coli strains. Using antibiotic resistance as a model system, we show that mutational spectra can alter these distributions substantially, ultimately determining the competitive ability of each strain across environments. Computer simulation showed that the effect of mutational spectrum on hitchhiking dynamics follows a non-linear function, implying that even slight spectrum-dependent fitness differences are sufficient to alter mutator success frequency by several orders of magnitude. These results indicate an unanticipated central role for the mutational spectrum in the evolution of bacterial mutation rates. At a practical level, this study indicates that knowledge of the molecular details of resistance determinants is crucial for minimizing mutator evolution during antibiotic therapy.
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spelling doaj-art-5bcd0d7d9e8340f1a7ce144721ea39b92025-08-20T03:01:15ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042013-01-0191e100316710.1371/journal.pgen.1003167Mutational spectrum drives the rise of mutator bacteria.Alejandro CouceJavier R GuelfoJesús BlázquezUnderstanding how mutator strains emerge in bacterial populations is relevant both to evolutionary theory and to reduce the threat they pose in clinical settings. The rise of mutator alleles is understood as a result of their hitchhiking with linked beneficial mutations, although the factors that govern this process remain unclear. A prominent but underappreciated fact is that each mutator allele increases only a specific spectrum of mutational changes. This spectrum has been speculated to alter the distribution of fitness effects of beneficial mutations, potentially affecting hitchhiking. To study this possibility, we analyzed the fitness distribution of beneficial mutations generated from different mutator and wild-type Escherichia coli strains. Using antibiotic resistance as a model system, we show that mutational spectra can alter these distributions substantially, ultimately determining the competitive ability of each strain across environments. Computer simulation showed that the effect of mutational spectrum on hitchhiking dynamics follows a non-linear function, implying that even slight spectrum-dependent fitness differences are sufficient to alter mutator success frequency by several orders of magnitude. These results indicate an unanticipated central role for the mutational spectrum in the evolution of bacterial mutation rates. At a practical level, this study indicates that knowledge of the molecular details of resistance determinants is crucial for minimizing mutator evolution during antibiotic therapy.https://journals.plos.org/plosgenetics/article/file?id=10.1371/journal.pgen.1003167&type=printable
spellingShingle Alejandro Couce
Javier R Guelfo
Jesús Blázquez
Mutational spectrum drives the rise of mutator bacteria.
PLoS Genetics
title Mutational spectrum drives the rise of mutator bacteria.
title_full Mutational spectrum drives the rise of mutator bacteria.
title_fullStr Mutational spectrum drives the rise of mutator bacteria.
title_full_unstemmed Mutational spectrum drives the rise of mutator bacteria.
title_short Mutational spectrum drives the rise of mutator bacteria.
title_sort mutational spectrum drives the rise of mutator bacteria
url https://journals.plos.org/plosgenetics/article/file?id=10.1371/journal.pgen.1003167&type=printable
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