Evolutionary changes in heat-inducible gene expression in lines of Escherichia coli adapted to high temperature

Michelle M. Riehle, Albert F. Bennett, Richard E. Lenski, Anthony D. Long

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

The involvement of heat-inducible genes, including the heat-shock genes, in the acute response to temperature stress is well established. However, their importance in genetic adaptation to long-term temperature stress is less clear. Here we use high-density arrays to examine changes in expression for 35 heat-inducible genes in three independent lines of Escherichia coli that evolved at high temperature (41.5°C) for 2,000 generations. These lines exhibited significant changes in heat-inducible gene expression relative to their ancestor, including parallel changes in fkpA, gapA, and hslT. As a group, the heat-inducible genes were significantly more likely than noncandidate genes to have evolved changes in expression. Genes encoding molecular chaperones and ATP-dependent proteases, key components of the cytoplasmic stress response, exhibit relatively little expression change; whereas genes with periplasmic functions exhibit significant expression changes suggesting a key role for the extracytoplasmic stress response in the adaptation to high temperature. Following acclimation at 41.5°C, two of the three lines exhibited significantly improved survival at 50°C, indicating changes in inducible thermotolerance. Thus evolution at high temperature led to significant changes at the molecular level in heat-inducible gene expression and at the organismal level in inducible thermotolerance and fitness.

Original languageEnglish (US)
Pages (from-to)47-58
Number of pages12
JournalPhysiological genomics
Volume14
DOIs
StatePublished - Oct 2003

Keywords

  • Adaptation
  • Arabinose-utilization phenotype
  • Functional genomics
  • Heat-shock response
  • Stress genes
  • Thermotolerance

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