Hydroperoxidase I catalyzes peroxidative activation of 3,3'-dichlorobenzidine to a mutagen in Salmonella typhimurium.
Dichlorobenzidine can be peroxidatively activated in Salmonella typhimurium Ames tester strains. Mutagenicity is observed when an S. typhimurium strain which is sensitive to frame-shift mutagens is incubated with dichlorobenzidine and hydrogen peroxide. In this paper, we show that the bacterial enzyme, hydroperoxidase I, is responsible for much of this activation. We constructed isogenic tester strains which lack hydroperoxidase I or II, due to Tn10 insertions in the structural genes encoding these proteins. Hydrogen peroxide-dependent mutagenicity of dichlorobenzidine was measured in each strain. A tester strain lacking hydroperoxidase I activity was much less sensitive than was the parent strain. When hydroperoxidase I activity was restored in this strain, via a plasmid-borne copy of the gene encoding the Escherichia coli protein, sensitivity to peroxide-dependent dichlorobenzidine mutagenicity was enhanced.
McGowan-Jordan
I J
IJ
Guelph-Waterloo Centre for Graduate Work in Chemistry, University of Guelph, Ontario, Canada.
Josephy
P D
PD
D015101:3,3'-Dichlorobenzidine / Q000493:pharmacokinetics* / Q000633:toxicity; D001560:Benzidines / Q000494:pharmacology; D001711:Biotransformation; D002374:Catalase / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005449:Fluorenes / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009152:Mutagenicity Tests; D009153:Mutagens; D009154:Mutation; D010084:Oxidation-Reduction; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
D001560:Benzidines; D029968:Escherichia coli Proteins; D005449:Fluorenes; D009153:Mutagens; D015101:3,3'-Dichlorobenzidine; C012177:2-aminofluorene; C021758:3,3',5,5'-tetramethylbenzidine; D006861:Hydrogen Peroxide; D002374:Catalase; C051253:katG protein, E coli