Adaptive benefits from small mutation supplies in an antibiotic resistance enzyme

Merijn L.M. Salverda, Jeroen Koomen, Bertha Koopmanschap, Mark P. Zwart, J.A.G.M. De Visser*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

19 Citations (Scopus)

Abstract

Populations with large mutation supplies adapt via the “greedy” substitution of the fittest genotype available, leading to fast and repeatable short-term responses. At longer time scales, smaller mutation supplies may in theory lead to larger improvements when distant high-fitness genotypes more readily evolve from lower-fitness intermediates. Here we test for long-term adaptive benefits from small mutation supplies using in vitro evolution of an antibiotic-degrading enzyme in the presence of a novel antibiotic. Consistent with predictions, large mutant libraries cause rapid initial adaptation via the substitution of cohorts of mutations, but show later deceleration and convergence. Smaller libraries show on average smaller initial, but also more variable, improvements, with two lines yielding alleles with exceptionally high resistance levels. These two alleles share three mutations with the large-library alleles, which are known from previous work, but also have unique mutations. Replay evolution experiments and analyses of the adaptive landscape of the enzyme suggest that the benefit resulted from a combination of avoiding mutational cohorts leading to local peaks and chance. Our results demonstrate adaptive benefits from limited mutation supplies on a rugged fitness landscape, which has implications for artificial selection protocols in biotechnology and argues for a better understanding of mutation supplies in clinical settings.
Original languageEnglish
Pages (from-to)12773-12778
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number48
DOIs
Publication statusPublished - 28 Nov 2017

Keywords

  • Adaptation
  • Antibiotic resistance
  • Experimental evolution
  • Fitness landscape
  • Mutation supply

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  • eFlux: Evolutionary microfluidics

    1/02/0931/05/12

    Project: EU research project

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