Repair of helix-stabilizing anthramycin-N2 guanine DNA adducts by UVRA and UVRB proteins.
The transfectivity of anthramycin (Atm)-modified phi X174 replicative form (RF) DNA in Escherichia coli is lower in uvrA and uvrB mutant cells but much higher in uvrC mutant cells compared to wild-type cells. Pretreatment of the Atm-modified phage DNA with purified UVRA and UVRB significantly increases the transfectivity of the DNA in uvrA or uvrB mutant cells. This pretreatment greatly reduces the UVRABC nuclease-sensitive sites (UNSS) and Atm-induced absorbance at 343 nm in the Atm-modified DNA without producing apurinic sites. The reduction of UNSS is proportional to the concentrations of UVRA and UVRB and the enzyme-DNA incubation time and requires ATP. We conclude that there are two different mechanisms for repairing Atm-N2 guanine adducts by UVR proteins: (1) UVRA and UVRB bind to the Atm-N2 guanine double-stranded DNA region and consequently release the Atm from the adducted guanine; (2) UVRABC makes an incision at both sides of the Atm-DNA adduct. The latter mechanism produces potentially lethal double-strand DNA breaks in Atm-modified phi X174 RF DNA in vitro.
Tang
M S
MS
Science Park-Research Division University of Texas, M.D. Anderson Cancer Center, Smithville 78957.
Nazimiec
M E
ME
Doisy
R P
RP
Pierce
J R
JR
Hurley
L H
LH
Alderete
B E
BE
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000876:Anthramycin / Q000737:chemistry*; D001080:Apurinic Acid / Q000737:chemistry; D001426:Bacterial Proteins / Q000378:metabolism*; D004249:DNA Damage; D004265:DNA Helicases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry; D004279:DNA, Viral / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism; D029968:Escherichia coli Proteins; D009154:Mutation; D013056:Spectrophotometry, Ultraviolet; D014162:Transfection
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C058093:UvrB protein, E coli; D000876:Anthramycin; D001080:Apurinic Acid; D004706:Endodeoxyribonucleases; C036385:endodeoxyribonuclease uvrABC; C068631:UvrA protein, E coli; D000251:Adenosine Triphosphatases; D004265:DNA Helicases