JB Download to Citation Manager
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Dukan, S.
Right arrow Articles by Touati, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Dukan, S.
Right arrow Articles by Touati, D.

J. Bacteriol., Nov 1996, 6145-6150, Vol 178, No. 21
Copyright © 1996, American Society for Microbiology

Hypochlorous acid stress in Escherichia coli: resistance, DNA damage, and comparison with hydrogen peroxide stress

S Dukan and D Touati
Institut Jacques Monod, CNRS-Universite Paris 7, France.

We have investigated the mechanisms of killing of Escherichia coli by HOCl by identifying protective functions. HOCl challenges were performed on cultures arrested in stationary phase and in exponential phase. Resistance to HOCl in both cases was largely mediated by genes involved in resistance to hydrogen peroxide (H2O2). In stationary phase, a mutation in rpoS, which controls the expression of starvation genes including those which protect against oxidative stress, renders the cells hypersensitive to killing by HOCl. RpoS-regulated genes responsible for this sensitivity were dps, which encodes a DNA-binding protein, and, to a lesser extent, katE and katG, encoding catalases; all three are involved in resistance to H2O2. In exponential phase, induction of the oxyR regulon, an adaptive response to H2O2, protected against HOCl exposure, and the oxyR2 constitutive mutant is more resistant than the wild-type strain. The genes involved in this oxyR- dependent resistance have not yet been identified, but they differ from those primarily involved in resistance to H2O2, including katG, ahp, and dps. Pretreatment with HOCl conferred resistance to H2O2 in an OxyR- independent manner, suggesting a specific adaptive response to HOCl. fur mutants, which have an intracellular iron overload, were more sensitive to HOCl, supporting the generation of hydroxyl radicals upon HOCl exposure via a Fenton-type reaction. Mutations in recombinational repair genes (recA or recB) increased sensitivity to HOCl, indicative of DNA strand breaks. Sensitivity was visible in the wild type only at concentrations above 0.6 mg/liter, but it was observed at much lower concentrations in dps recA mutants.


This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 1996 by the American Society for Microbiology. All rights reserved.