Substrate specificity of the Escherichia coli Fpg protein (Formamidopyrimidine - DNA glycosylase): Excision of purine lesions in DNA produced by ionizing radiation or photosensitization

Journal Article · Tue Jan 14 00:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00116a016· OSTI ID:5611624

Boiteux, S; Laval, J ^[1]; Gajewski, E; Dizdaroglu, M ^[2]

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1. Inst. Gustave Roussy, Villejuif (France)
2. National Inst. of Standards and Tech., Gaithersburg, MD (United States)

The authors have investigated the excision of a variety of modified bases from DNA by the Escherichia coli Fpg protein (formamidopyrimidine-DNA glycosylase). DNA used as a substrate was modified either by exposure to ionizing radiation or by photosensitization using visible light in the presence of methylene blue (MB). The technique of gas chromatography/mass spectrometry, which can unambiguously identify and quantitate pyrimidine- and purine-derived lesions in DNA, was used for analysis of hydrolyzed and derivatized DNA samples. Thirteen products resulting from pyrimidines and purines were detected in {gamma}-irradiated DNA, whereas only the formation of 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 8-hydroxyguanine (8-OH-Gua) was observed in visible light/MB-treated DNA. Analysis of {gamma}-irradiated DNA after incubation with the Fpg protein followed by precipitation revealed that the Fpg protein significantly excised 4,6-diamino-5-formamidopyrimidine (FapyAde), FapyGua, and 8-OH-Gua. The excision of a small but detectable amount of 8-hydroxyadenine was also observed. The results suggest that one of the biological roles of the Fpg protein, which is present in bacteria as well as in mammalian cells, is the repair of DNA damage caused by free radicals or by other oxygen-derived species such as singlet oxygen. The Fpg protein appears to be specific for recognition of imidazole ring opened purines and 8-hydroxypurines in DNA and may complement pyrimidine-specific enzymes in repair of DNA damage in vivo.

• OSTI ID: 5611624
• Journal Information: Biochemistry; (United States), Vol. 31:1; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
DNA
BIOLOGICAL RADIATION EFFECTS
EXCISION REPAIR
MOLECULAR BIOLOGY
DNA REPAIR
ESCHERICHIA COLI
GAMMA RADIATION
GLYCOSYL HYDROLASES
IMIDAZOLES
MASS SPECTROSCOPY
PHOTOSENSITIVITY
PURINES
RADICALS
SUBSTRATES
AROMATICS
AZAARENES
AZOLES
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
ELECTROMAGNETIC RADIATION
ENZYMES
HETEROCYCLIC COMPOUNDS
HYDROLASES
IONIZING RADIATIONS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROTEINS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
SENSITIVITY
SPECTROSCOPY
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture