Induction of DnaK upon γ-Irradiation at High and Low Rates in Escherichia coli

Linda Saucier, Claudine Dube, Anthony Guernec, Fadia Naim

Département des sciences animales, Faculté des sciences de l’agriculture et de l’alimentation, Université Laval, Québec, Québec, Canada.
Food Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, Québec, Canada.

DOI: 10.4236/fns.2012.310178                

Abstract

DnaK is implicated in protein folding, repair and degradation. Its protective role during heat shock is well documented and many other stresses can also induce its production. Using a competitive ELISA, intracellular DnaK concentrations were determined in Escherichia coli ATCC 25922 exposed to a γ-irradiation dose of 0.3 KGy applied either at high (8 × 10^-2 KGy/min) or low rates (3 × 10^-3 KGy/min) and with or without a recuperation period of 22 h at 37℃ post-treatment. All four irradiation treatments reduced cell counts similarly and significantly compared to the control (P < 0.0001). However, the highest DnaK concentration was observed in cells irradiated at low rate without recuperation (105,416 molecules/cell; P = 0.0001). Furthermore, DnaK levels remained higher than the control (38,500 molecules/ cell) after the recuperation period (P < 0.05). Variation in the intracellular DnaK concentration indicates that the bacterial stress response was modulated differently according to the irradiation treatment (P = 0.0001).

Keywords

DnaK; Chaperone; Irradiation; Bacterial Stress Response; Efficacy of Antimicrobials

Conflicts of Interest

The authors declare no conflicts of interest.

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