Document Detail

Mutation accumulation and fitness in mutator subpopulations of Escherichia coli.
MedLine Citation:
PMID:  23221876     Owner:  NLM     Status:  MEDLINE    
Bacterial populations in clinical and laboratory settings contain a significant proportion of mutants with elevated mutation rates (mutators). Mutators have a particular advantage when multiple beneficial mutations are needed for fitness, as in antibiotic resistance. Nevertheless, high mutation rates potentially lead to increasing numbers of deleterious mutations and subsequently to the decreased fitness of mutators. To test how fitness changed with mutation accumulation, genome sequencing and fitness assays of nine Escherichia coli mutY mutators were undertaken in an evolving chemostat population at three time points. Unexpectedly, the fitness in members of the mutator subpopulation became constant despite a growing number of mutations over time. To test if the accumulated mutations affected fitness, we replaced each of the known beneficial mutations with wild-type alleles in a mutator isolate. We found that the other 25 accumulated mutations were not deleterious. Our results suggest that isolates with deleterious mutations are eliminated by competition in a continuous culture, leaving mutators with mostly neutral mutations. Interestingly, the mutator-non-mutator balance in the population reversed after the fitness plateau of mutators was reached, suggesting that the mutator-non-mutator ratio in populations has more to do with competition between members of the population than the accumulation of deleterious mutations.
Ram P Maharjan; Bin Liu; Yang Li; Peter R Reeves; Lei Wang; Thomas Ferenci
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-12-05
Journal Detail:
Title:  Biology letters     Volume:  9     ISSN:  1744-957X     ISO Abbreviation:  Biol. Lett.     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2012-12-10     Completed Date:  2013-05-09     Revised Date:  2014-02-25    
Medline Journal Info:
Nlm Unique ID:  101247722     Medline TA:  Biol Lett     Country:  England    
Other Details:
Languages:  eng     Pagination:  20120961     Citation Subset:  IM    
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MeSH Terms
DNA Glycosylases / genetics*
Escherichia coli / genetics*
Escherichia coli Proteins / genetics*
Genetic Fitness
Genome, Bacterial*
Microbial Interactions
Mutation Rate*
Time Factors
Reg. No./Substance:
0/Escherichia coli Proteins; EC 3.2.2.-/DNA Glycosylases; EC 3.2.2.-/mutY adenine glycosylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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