Copper-dependent cleavage of DNA by bleomycin

Abstract

DNA strand scission by bleomycin in the presence of Cu and Fe was further characterized. It was found that DNA degradation occurred readily upon admixture of Cu(I) or Cu(II) + dithiothreitol + bleomycin, but only where the order of addition precluded initial formation of Cu(II)--bleomycin or where sufficient time was permitted for reduction of the formed Cu(II)--bleomycin to Cu(I)--bleomycin. DNA strand scission mediated by Cu + dithiothreitol + bleomycin was inhibited by the copper-selective agent bathocuproine when the experiment was carried out under conditions consistent with Cu chelation by bathocuproine on the time scale of the experiment. Remarkably, it was found that the extent of DNA degradation obtained with bleomycin in the presence of Fe and Cu was greater than that obtained with either metal ion alone. A comparison of the sequence selectivity of bleomycin in the presence of Cu and Fe using 32P-end-labeled DNA duplexes as substrates revealed significant differences in sites of DNA cleavage and in the extent of cleavage at sites shared in common. For deglycoblemycin and decarbamoylbleomycin, whose metal ligation is believed to differ from that of bleomycin itself, it was found that the relative extents of DNA cleavage in the presence of Cu were not in the same order as those obtained in the presence of Fe. The bleomycin-mediated oxygenation products derived from cis-stilbene were found to differ in type and amount in the presence of added Cu vs. added Fe. Interestingly, while product formation from cis-stilbene was decreased when excess Fe was added to a reaction mixture containing 1:1 Fe(III) and bleomycin, the extent of product formation was enhanced almost 4-fold in reactions that contained 5:1, as compared to 1:1, Cu and bleomycin. The results of these experiments are entirely consistent with the work of Sugiura [Sugiura, Y. (1979) Biochem. Biophys. Res. Commun. 90, 375-383], who first demonstrated the generation of reactive oxygen species upon admixture of O2 and Cu(I)--bleomycin.

Human AlkB Homolog ABH8 Is a tRNA Methyltransferase Required for Wobble Uridine Modification and DNA Damage Survival

“…To determine whether the sensitivity phenotype exhibited by ABH8-depleted cells is specific to alkylation damage, we also tested sensitivity to bleomycin, which damages DNA through a mechanism different from that of MMS. Bleomycin intercalates between DNA base pairs and catalyzes free radical production to induce double-strand breaks (13). We found that ABH8-depleted cell lines displayed significant sensitivity to bleomycin, similar to their sensitivity to MMS (Fig.…”

Resveratrol–Cu(II) induced DNA breakage in human peripheral lymphocytes: Implications for anticancer properties

“…Further, it was also pointed out that several properties of these compounds such as binding to DNA and its degradation are similar to those of known anticancer drugs such as bleomycin, adriamycin and 4 0 -(9-acrdinylamino) methanesulphone-m-anisidine (mAMSA) [18][19][20]. It has been shown that the polyphenolic resveratrol is also capable of strand breakage in DNA in the presence of copper ions [21].…”

Investigation into the mechanism of action of the antimicrobial peptides Os and Os-C derived from a tick defensin

“…Ionic interactions between the cationic peptide and plasmid DNA reduce the charge on the plasmid and subsequently the migration is retarded. Additionally peptide binding can cause quenching of plasmid dye fluorescence or may cause the transformation of supercoiled plasmid DNA to the open circular and linear forms as an indication of DNA damage [9,19,34]. A single-strand break results in a relaxed circular form of DNA, and a double strand break results in a linear form of DNA [36].…”