Aerobic fate of the C-3'-thymidinyl radical in single-stranded DNA.
Oxidative events that target the sugar-phosphate backbone of DNA can lead to reactive fragments that interfere with DNA repair, transcription and translation by the formation of cross-links and adducts of proteins and nucleobases. Here we report the formation of several such lesions through the aerobic degradation of an independently generated C-3'-thymidinyl radical in 2'-deoxyoligonucleotides. Individual fragments were identified by independent synthesis and comparison of retention times in high-performance liquid chromatography (HPLC) and/or matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF MS) along with gel electrophoresis. The formation of this reactive intermediate in the presence of oxygen was found to produce 3'-phosphoglycolaldehyde (3'-PGA) as well as 3'-ketoenolether (3'-KEE), 3'-phosphoglycolate (3'-PG), and 5'-aldehyde terminated oligonucleotide fragments. Additionally, a significant outcome of C-3'-thymidinyl radical formation in DNA oligomers is a strand break resulting in one 3'- and two 5'-phosphate-terminated oligomers. These results suggest the involvement of several sugar derived reactive species upon C-3'-radical initiated scission of single-stranded DNA under aerobic conditions. The electrophilic nature of several of these products as well as their formation through a single oxidative event can make the presence of a C-3'-DNA radical more detrimental to the cell than products derived from more frequently occurring DNA sugar radicals.
Lahoud
Georges A
GA
Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
Hitt
Anne L
AL
Bryant-Friedrich
Amanda C
AC
D000332:Aerobiosis; D002851:Chromatography, High Pressure Liquid; D004277:DNA, Single-Stranded / Q000737:chemistry*; D009841:Oligonucleotides / Q000737:chemistry*; D063065:Organophosphonates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013936:Thymidine / Q000737:chemistry*
D004277:DNA, Single-Stranded; D009841:Oligonucleotides; D063065:Organophosphonates; D013936:Thymidine