Identification and quantitation of the lesion accompanying base release in bleomycin-mediated DNA degradation

Abstract

Interaction of bleomycin, Fe2+, and limiting O2 or bleomycin, Fe3+, and H 2 0 2 with DNA results in the production of free nucleic acid base and an oxidatively damaged sugar lesion that undergoes strand scission subsequent to treatment with alkali. The hexamer d(CGCGCG) has been utilized to develop a protocol to establish the identity of this lesion as a 2'-deoxy-4'-pentulose moiety and to establish its stoichiometric production with respect to free nucleic acid base. The protocol developed has been extended to a variety of heterogeneous DNAs with similar results. The predominant pathway for base release in bleomycin-mediated DNA degradation is the result of chemistry at the C-4' carbon of the sugar moiety.

Sequence-specific Changes in the Metal Site of Ferric Bleomycin Induced by the Binding of DNA

“…We have now extended our studies to Fe-BLM bound to the self-complementary hexanucleotides, d(CGCGCG) and d(ATATAT), with the intent of detecting structural changes in the metal binding site that correlate with the sequence specificity of DNA cleavage. The use of hexameric DNA sequences is based on reports that Fe-BLM-mediated cleavage of d(CGCGCG) has been well characterized and shown to occur overwhelmingly at the third deoxycytosine residue from the 5Ј-end (dC-5) (25)(26)(27). Although cleavage of AT sites by Fe-BLM has also been documented, scission at these sites occurs with much lower efficiency (9,10).…”

The Saccharomyces cerevisiae IMP2 Gene Encodes a Transcriptional Activator That Mediates Protection against DNA Damage Caused by Bleomycin and Other Oxidants

“…The antitumor effect of BLM is exerted through oxidative lesions in chromosomal DNA, formed via a free radical-reactive complex that is produced when BLM binds to iron and oxygen in vivo (6,64). The activated Fe ⅐ BLM complex takes a hydrogen atom from the 4Ј-carbon of deoxyribose, resulting in two types of lesions: (i) oxidized apurinic/apyrimidinic (AP) sites and (ii) DNA single-strand breaks that terminate with 3Ј-phosphoglycolate (16,44,64). Noncoding AP sites lead to the incorporation of incorrect nucleotides by DNA polymerase (29,34).…”

Cellular role of yeast Apn1 apurinic endonuclease/3'-diesterase: repair of oxidative and alkylation DNA damage and control of spontaneous mutation.

“…The hydroxyl radical is probably the proximal species that causes DNA damage by oxidative mutagens (11) and accounts for much of the cellular damage caused by ionizing radiation (35). The antitumor drugs bleomycin (6,26) and neocarzinostatin (24) also mediate free-radical attack on DNA and cause some of the same DNA damages produced by X rays and other oxidative mutagens. These lesions include oxidized abasic sites and DNA strand breaks (10,35).…”