Inefficient repair of RNA x DNA hybrids.
RNA x DNA hybrids are commonly observed during normal biological processes. We tested the ability of three DNA-repair enzymes to remove lesions from the DNA strand of RNA x DNA heteroduplexes. Three nucleotide analogs, 5-hydroxy-2'-deoxycytidine triphosphate, 8-oxo-2'-deoxyguanosine triphosphate, and O6-methyl-2'-deoxyguanosine triphosphate, representative of lesions generated by oxygen damage and methylating agents, were incorporated into the DNA strand synthesized using either a DNA or RNA template. The extended DNA x DNA and RNA x DNA hybrids were used as substrates for bacterial formamidopyrimidine-DNA glycosylase, Nth protein (endonuclease III) and O6-methylguanine-DNA methyltransferase. We show that all three lesions are readily cleaved from the DNA strand of a DNA x DNA duplex but are relatively resistant to cleavage when present in the DNA strand of an RNA x DNA hybrid. Our in vitro studies suggest that damaged DNA in RNA x DNA hybrids is less likely to be repaired in vivo.
Kamath-Loeb
A S
AS
Department of Pathology, University of Washington, Seattle 98195, USA.
Hizi
A
A
Tabone
J
J
Solomon
M S
MS
Loeb
L A
LA
D004249:DNA Damage; D004260:DNA Repair; D009690:Nucleic Acid Conformation; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000378:metabolism; D012313:RNA / Q000378:metabolism*
D012313:RNA; D019853:O(6)-Methylguanine-DNA Methyltransferase