title: Oxidative Stress in Shiga Toxin Production by Enterohemorrhagic Escherichia coli.
abstract: Virulence of enterohemorrhagic Escherichia coli (EHEC) strains depends on production of Shiga toxins. These toxins are encoded in genomes of lambdoid bacteriophages (Shiga toxin-converting phages), present in EHEC cells as prophages. The genes coding for Shiga toxins are silent in lysogenic bacteria, and prophage induction is necessary for their efficient expression and toxin production. Under laboratory conditions, treatment with UV light or antibiotics interfering with DNA replication are commonly used to induce lambdoid prophages. Since such conditions are unlikely to occur in human intestine, various research groups searched for other factors or agents that might induce Shiga toxin-converting prophages. Among other conditions, it was reported that treatment with H2O2 caused induction of these prophages, though with efficiency significantly lower relative to UV-irradiation or mitomycin C treatment. A molecular mechanism of this phenomenon has been proposed. It appears that the oxidative stress represents natural conditions provoking induction of Shiga toxin-converting prophages as a consequence of H2O2 excretion by either neutrophils in infected humans or protist predators outside human body. Finally, the recently proposed biological role of Shiga toxin production is described in this paper, and the "bacterial altruism" and "Trojan Horse" hypotheses, which are connected to the oxidative stress, are discussed.
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Licznerska
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Bożena
authors.initials: B
authors.lastname: Nejman-Faleńczyk
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Bloch
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Dydecka
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Gracja
authors.initials: G
authors.lastname: Topka
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Gąsior
authors.affiliation: Laboratory of Molecular Biology (Affiliated with the University of Gdańsk), Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Węgrzyn
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Węgrzyn
mesh_terms: D000818:Animals; D054324:Enterohemorrhagic Escherichia coli / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D018384:Oxidative Stress; D039002:Prophages / Q000378:metabolism; D022621:Shiga Toxin / Q000096:biosynthesis*
chemical_list: D022621:Shiga Toxin; D006861:Hydrogen Peroxide