DNA Strand Scission by Bleomycin Group Antibiotics

Abstract

Certain properties of the bleomycin analogs deglycobleomycin A2 and decarbamoylbleomycin A2 have been characterized. In common with bleomycin A2, both deglycobleomycin A2 and decarbamoylbleomycin A2 were found to mediate DNA degradation in the presence of Fe(II) + O2. Both analogs were found to have essentially the same sequence selectivity for DNA strand scission as bleomycin A2 when a 5'-[23P]-end-labeled linear duplex DNA derived from SV40 DNA was employed as a substrate. Product analysis for the three analogs was carried out by assay for malondialdehyde (precursors) after digestion of calf thymus DNA, and also by hplc analysis of the digestion products formed from the dodecanucleotide d(CGCTTTAAAGCG). All three Fe(II) X bleomycin A2 analogs produced the same products, albeit not in the same relative amounts.

Crystal structure of DNA-bound Co(III)·bleomycin B 2 : Insights on intercalation and minor groove binding

“…Thus, no functional role for the gulopyranose can be assigned based on structural analysis. Nonetheless, an important role for the disaccharide moiety in DNA-binding and cleavage by HOOFe(III)⅐bleomycin has been indicated by the reduced DNA cleavage activity of deglycobleomycin in vitro (35,36). One possibility is that the gulopyranose serves as a ''space-filling'' unit allowing the metal binding domain to adopt an optimized and stabilized orientation relative to the target C4Ј-H. We further note that the respective orientations and intramolecular hydrogen-bonding interactions of the metal-binding and disaccharide domains of Co⅐BLM bound to 1 are similar to those observed in the crystal structure of Cu(II)⅐bleomycin bound to a bleomycin resistance protein (37) (Fig.…”

In Vivo Manipulation of the Bleomycin Biosynthetic Gene Cluster in Streptomyces verticillus ATCC15003 Revealing New Insights into Its Biosynthetic Pathway

“…4 and Table 1), and their comparison with the BLM A2 spectroscopic data reported in the literature (30) confirmed that the isolated intermediate indeed represents 3-MOP-decarbamoyl-BLM. Decarbamoyl-BLM has previously been reported as a partial hydrol- ysis product of BLM under basic aqueous conditions after prolonged storage but has only been accessible in very small quantities (35,36). Additionally, decarbamoyl-BLM demethyl-A2, lacking one methyl group in the A2 terminal amine, was isolated as a byproduct during the tedious multi-step total chemical synthesis of BLM demethyl-A2 (37).…”

“…Although several in vitro studies have shown that deglyco-BLMs exhibit reduced DNA cleavage activities compared with BLM A2 or B2 (36,39,40), the role of the carbamoyl group remained controversial. Decarbamoyl-BLM was reported to show significantly reduced malondialdehyde forming activity, but similar oligonucleotide cleavage activity compared with BLM A2 (36), and similar DNA cleavage activity as BLM in the presence of Fe 2ϩ , but reduced activity in the presence of Cu 2ϩ and dithiothreitol (39), and oligonucleotide cleavage activities much closer to deglyco-BLM A2 rather than BLM A2 (41). Our results obtained with 3-MOP-decarbamoyl-BLM, however, indicate a significant impact of the carbamoyl group on DNA cleavage activity resulting in ϳ10-fold reduced plasmid relaxation efficiency compared with BLM A2 and B2.…”

Bioactive Constituents of Conyza albida

“…Further mechanistic assays were performed for the pure compounds 1 to 4 in the DNA methyl green (10), the DNA strandscission (12) and in the topoisomerase I inhibition assays (10). Then, in order to determine if cytotoxicity to KB cells was due to the capacity of the compounds to interact with DNA, a colorimetric microassay was carried out.…”

“…DNA strand-scission assay: The DNA strand-scission assay was adapted from a previously described procedure (12). Briefly, samples were dissolved in DMSO and assayed at 100, 10 and 1 mg/ml.…”