Escherichia coli Fpg protein and UvrABC endonuclease repair DNA damage induced by methylene blue plus visible light in vivo and in vitro.
pBR322 plasmid DNA was treated with methylene blue plus visible light (MB-light) and tested for transformation efficiency in Escherichia coli mutants defective in either formamidopyrimidine-DNA glycosylase (Fpg protein) and/or UvrABC endonuclease. The survival of pBR322 DNA treated with MB-light was not significantly reduced when transformed into either fpg-1 or uvrA single mutants compared with that in the wild-type strain. In contrast, the survival of MB-light-treated pBR322 DNA was greatly reduced in the fpg-1 uvrA double mutant. The synergistic effect of these two mutations was not observed in transformation experiments using pBR322 DNA treated with methyl methanesulfonate, UV light at 254 nm, or ionizing radiation. In vitro experiments showed that MB-light-treated pBR322 DNA is a substrate for the Fpg protein and UvrABC endonuclease. The number of sites sensitive to cleavage by either Fpg protein or UvrABC endonuclease was 10-fold greater than the number of apurinic-apyrimidinic sites indicated as Nfo protein (endonuclease IR)-sensitive sites. Seven Fpg protein-sensitive sites per PBR322 molecule were required to produce a lethal hit when transformed into the uvrA fpg-1 mutant. These results suggest that MB-light induces DNA base modifications which are lethal and that these modifications are repaired by Fpg protein and UvrABC endonuclease in vivo and in vitro. Therefore, one of the physiological functions of Fpg protein might be to repair DNA base damage induced by photosensitizers and light.
Czeczot
H
H
Groupe Réparation des lésions radio-chimioinduites, UA158 CNRS, U140 INSERM, Institut Gustave-Roussy, Villejuif, France.
Tudek
B
B
Lambert
B
B
Laval
J
J
Boiteux
S
S
D001426:Bacterial Proteins / Q000494:pharmacology*; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair / Q000502:physiology*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043382:DNA-Formamidopyrimidine Glycosylase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004305:Dose-Response Relationship, Drug; D004706:Endodeoxyribonucleases / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005720:Gamma Rays / Q000009:adverse effects; D008027:Light / Q000009:adverse effects; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009699:N-Glycosyl Hydrolases / Q000502:physiology*; D010957:Plasmids; D011832:Radiation Injuries; D014170:Transformation, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D004247:DNA; D008741:Methyl Methanesulfonate; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; C036385:endodeoxyribonuclease uvrABC; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008751:Methylene Blue