Effect of γ-irradiation on gene expression of heat shock proteins in the foodborne pathogen Escherichia coli O157:H7

Int J Radiat Biol. 2014 Mar;90(3):268-73. doi: 10.3109/09553002.2014.859766. Epub 2014 Feb 6.


Purpose: The expression levels of seven genes (clpB, dnaK, groES, grpE, htpG, htpX and ibpB) encoding heat shock proteins (HSP) in Escherichia coli O157:H7 (E. coli) gamma irradiated was investigated. Timing impact of post-irradiated RNA extraction on the expression levels of these seven genes was also studied at a dose damaging the bacterial cells (0.4 kGy).

Methods: Bacterial samples were γ-irradiated at 0.4 kGy and at a lethal dose of 1.3 kGy. RNA was extracted at 0 min post irradiation for both irradiation doses and at 15, 30, 60, 90 or 120 min post-irradiation at the dose damaging the cells. Quantification of the gene expression was performed using quantitative real-time polymerase chain reaction (q-RT-PCR).

Results: The expression of genes encoding HSP was a very dynamic process evolving rapidly when E. coli cells were irradiated at 0.4 kGy. Notably, groES, grpE and ibpB were more up- regulated at 1.3 kGy than those at 0.4 kGy.

Conclusions: For the seven genes studied there were more damaged proteins during irradiation at the lethal dose and this dose causes increased expression in HSP which contributes to damage reparation. Expression patterns of genes encoding HSP in E. coli treated by γ-irradiation are different from those treated by heat shock.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Colony Count, Microbial
  • DNA Primers / genetics
  • Dose-Response Relationship, Radiation
  • Escherichia coli O157 / genetics*
  • Escherichia coli O157 / radiation effects*
  • Escherichia coli Proteins / metabolism
  • Food Irradiation*
  • Food Microbiology
  • Gamma Rays*
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial / radiation effects*
  • Heat-Shock Proteins / metabolism*
  • Real-Time Polymerase Chain Reaction
  • Stem Cells
  • Time Factors


  • DNA Primers
  • Escherichia coli Proteins
  • Heat-Shock Proteins