The reactivity of the 2-deoxyribonolactone lesion in single-stranded DNA and its implication in reaction mechanisms of DNA damage and repair.
The formal C1'-oxidation product, 2-deoxyribonolactone, is formed as a result of DNA damage induced via a variety of agents, including gamma-radiolysis and the enediyne antitumor antibiotics. This alkaline labile lesion may also be an intermediate during DNA damage induced by copper-phenanthroline. Oligo-nucleotides containing this lesion at a defined site were formed via aerobic photolysis of oligonucleotides containing a photolabile ketone, and were characterized by gel electrophoresis and electrospray mass spectrometry (ESI-MS). Treatment of oligo-nucleotides containing the lesion with secondary amines produces strand breaks consisting of 3'-phosphate termini, and products which migrate more slowly in polyacrylamide gels. MALDI-TOF mass spectrometry analysis indicates that the slower moving products are formal adducts of the beta-elimination product resulting from 2-deoxyribonolactone and one molecule of amine. The addition of beta-mercapto-ethanol to the reaction mixture produces thiol adducts as well. The stability of these adducts suggests that they cannot be the labile species characterized by gel electrophoresis in copper-phenanthroline-mediated strand scission. The characterization of these adducts by mass spectrometry also provides, by analogy, affirmation of proposals regarding the reactivity of nucleophiles with the beta-elimination product of abasic sites. Finally, the effects of this lesion and the various adducts on DNA repair enzymes are unknown, but their facile generation from oligonucleotides containing a photolabile ketone suggests that such issues could be addressed.
Hwang
J T
JT
Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
Tallman
K A
KA
Greenberg
M M
MM
D000641:Ammonia; D018736:DNA Adducts; D004249:DNA Damage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry*; D005029:Ethylenediamines; D008623:Mercaptoethanol; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010880:Piperidines; D013400:Sugar Acids / Q000737:chemistry*; D014867:Water
D018736:DNA Adducts; D004277:DNA, Single-Stranded; D005029:Ethylenediamines; D009838:Oligodeoxyribonucleotides; D010880:Piperidines; D013400:Sugar Acids; D014867:Water; C027450:dimethylethylenediamine; C056405:2,4,5-trihydroxypentanoic acid gamma-lactone; D008623:Mercaptoethanol; C032727:piperidine; D000641:Ammonia