Document Detail

Formation of 8-oxoguanine in cellular DNA of Escherichia coli strains defective in different antioxidant defences.
MedLine Citation:
PMID:  9862189     Owner:  NLM     Status:  MEDLINE    
This paper examines the relationship in Escherichia coli between the in vivo content of 8-oxoguanine (8-oxoG) in chromosomal DNA and deficiencies of various key antioxidant defences. The structural genes for catalases (katG and katE), cytosolic superoxide dismutases (sodA and sodB) or formamidopyrimidine-DNA glycosylase (fpg) were inactivated to obtain bacterial strains lacking the scavenger enzymes for H2O2 or O2.- or the DNA repair protein for 8-oxoG. Wild-type bacteria showed 5-fold increased sensitivity to both lethality and mutagenesis by H2O2 in K medium (1% casamino acids and 1% glucose), as compared with nutrient broth. This higher sensitivity was associated with increased chromosomal oxidative damage, estimated as the 8-oxodG content, and with a marked decrease in both catalase and SOD activities. Bacteria lacking both cytosolic SODs (sodA sodB mutant) displayed increased 8-oxodG content in chromosomal DNA (2.8-fold that of the wild-type) when grown under standard aerated conditions. Comparatively, no significant difference in 8-oxodG content was observed in cells grown without aeration. Bacteria totally devoid of catalase activity (katG katE mutant) showed wild-type contents of 8-oxodG in chromosomal DNA when grown under aerated conditions. Nevertheless, the protective role of catalase in preventing formation of 8-oxodG in chromosomal DNA became evident under oxidative stress conditions: growth under hyperoxygenation and, particularly, following H2O2 exposure. Catalase deficiency resulted in a dramatic decrease in viability after H2O2 exposure. A deficiency of Fpg protein also sensitized E.coli to H2O2 lethality, though to lesser extent than a deficiency of catalase activity. However, the scavenger enzyme and the DNA repair protein protected equally against 8-oxoG formed in vivo upon H2O2 treatment.
J Alhama; J Ruiz-Laguna; A Rodriguez-Ariza; F Toribio; J López-Barea; C Pueyo
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Mutagenesis     Volume:  13     ISSN:  0267-8357     ISO Abbreviation:  Mutagenesis     Publication Date:  1998 Nov 
Date Detail:
Created Date:  1999-02-25     Completed Date:  1999-02-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8707812     Medline TA:  Mutagenesis     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  589-94     Citation Subset:  IM    
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, España.
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MeSH Terms
Alkaline Phosphatase / chemistry,  metabolism
Bacterial Proteins / genetics,  metabolism
Catalase / drug effects,  genetics*,  metabolism
Cell Division / drug effects,  genetics
Culture Media
DNA, Bacterial / chemistry,  drug effects,  metabolism*
Escherichia coli / classification,  drug effects,  genetics*
Guanine / analogs & derivatives*,  biosynthesis
Hydrogen Peroxide / pharmacology
Oxidants / metabolism
Oxidative Stress
Peroxidases / drug effects,  genetics,  metabolism
Species Specificity
Superoxide Dismutase / drug effects,  genetics*,  metabolism
Reg. No./Substance:
0/Bacterial Proteins; 0/Culture Media; 0/DNA, Bacterial; 0/Oxidants; 0/SodA protein, Bacteria; 0/SodB protein, Bacteria; 5614-64-2/8-hydroxyguanine; 73-40-5/Guanine; 7722-84-1/Hydrogen Peroxide; EC 1.11.1.-/Peroxidases; EC 1.11.1.-/hydroperoxidase II; EC; EC HPI; EC Dismutase; EC Phosphatase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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