Genome-wide hypermutation in a subpopulation of stationary-phase cells underlies recombination-dependent adaptive mutation

Joel Torkelson, Reuben S. Harris, Mary Jane Lombardo, Jayan Nagendran, Carl Thulin, Susan M. Rosenberg

Research output: Contribution to journalArticlepeer-review

213 Scopus citations

Abstract

Stationary-phase mutation in microbes can produce selected ('adaptive') mutants preferentially. In one system, this occurs via a distinct, recombination-dependent mechanism. Two points of controversy have surrounded these adaptive reversions of an Escherichia coli lac mutation. First, are the mutations directed preferentially to the selected gene in a Lamarckian manner? Second, is the adaptive mutation mechanism specific to the F plasmid replicon carrying lac? We report that lac adaptive mutations are associated with hypermutation in unselected genes, in all replicons in the cell. The associated mutations have a similar sequence spectrum to the adaptive reversions. Thus, the adaptive mutagenesis mechanism is not directed to the lac genes, in a Lamarckian manner, nor to the F' replicon carrying lac. Hypermutation was not found in non-revertants exposed to selection. Therefore, the genome-wide hypermutation underlying adaptive mutation occurs in a differentiated subpopulation. The existence of mutable subpopulations in non-growing cells is important in bacterial evolution and could be relevant to the somatic mutations that give rise to cancers in multicellular organisms.

Original languageEnglish (US)
Pages (from-to)3303-3311
Number of pages9
JournalEMBO Journal
Volume16
Issue number11
DOIs
StatePublished - Jun 2 1997

Keywords

  • Adaptive mutation
  • Directed mutation
  • Evolution
  • Recombination
  • Stationary phase

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