The Interaction of Daunomycin with Polydeoxynucleotides

Abstract

The ability of daunomycin to bind to various DNA polymers has been studied by thermal denaturation, spectrophotometric analysis and inhibition of the polymerisation reactions catalysed by Escherichia coli DNA polymerase I and rat liver DNA polymerase CI. The quantitative binding measurements revealed that the antibiotic binds tightly to all synthetic polydeoxynucleotides studied.The results demonstrated that daunomycin can bind with equal affinity to dG . dC or dA . dT basepaired sequences. However, the number of binding sites per nucleotide for poly (dA) . poly(dT) is significantly lower than that found for poly (dA-dT) . poly(dA-dT), thus indicating an appreciable preference of the drug for the alternating copolymer.The inactivation of the template properties of the synthetic DNA polymers in the DNA polymerase system is consistent with their daunomycin binding ability. However, a lack of correlation was observed between the drug binding ability of different DNA polymers and the binding-induced stabilisation of the double helix to heat denaturation.Various lines of evidence strongly suggest that most of the biological effects of daunomycin can be ascribed to its binding to DNA with consequent impairment of nucleic acid synthesis [l]. Binding of daunomycin to DNA occurs by a strong primary process attributed to intercalation [2,3], i.e. insertion of the planar aromatic tetracyclic ring system into the double helix of DNA, with the plane of the chromophore parallel to the planes of the DNA base pairs and a concomitant slight untwisting of the DNA sugar-phosphate backbones [4 -61. In this binding mode, no significant preference for d A . dT or dG . dC sites has been detected [7]. However, differential inhibition of DNA-dependent reactions appeared related to polynucleotide base composition and/or nucleotide sequence [8,9]. In addition, the binding of nogalamycin and steffimycin B (two closely related anthracycline antibiotics) has been postulated to be dependent on the dA + dT content of the polymer [10,ll]. Therefore, it is important to gain more information about the nature and specificity of interaction between daunomycin and nucleic acids.In the present paper we report on the binding of daunomycin to a variety of synthetic polynucleotides Abbreviation. dNTPs, deoxyribonucleoside triphosphates. Abbreviations for polynucleotides follow IUPAC/IUB Recommendations, see Eur. J . Biochem. 15, 203 -208 (1970).Enzyme. DNA polymerase (EC 2.7.7.7).to determine what selectivity the antibiotic may display with respect to its capacity to bind to polynucleotides that have a different base composition and nucleotide sequence. The data presented show that the template inactivation by the antibiotic in the bacterial DNA polymerase system is in accordance with its binding properties. MATERIALS AND METHODS Nucleotides and Polyde0,~ynucleotidesAll of the polydeoxynucleotides used were obtained from P-L Biochemicals Inc. (Milwaukee, Wis., U.S.A.) and were dissolved in 0.01 M NaCl for thermal denaturation studies and in 0.15 M NaC...

Equilibrium studies on the interaction of daunomycin with deoxypolynucleotides

“…The difference in the exclusion parameter is essentially the same as that reported here. Phillips et al (1978) reported equal binding affinities for the interaction of daunomycin with the same series of deoxypolynucleotides used in this study. They did note, however, differences in the apparent site size, which roughly followed the trend reported here.…”

Inhibition of chicken myeloblastosis RNA polymerase II activity by adriamycin

“…Adriamycin was reported to inhibit the activities of DNA polymerases (Goodman et al, 1974;Zunino et al, 1975b) and RNA polymerases (Zunino et al, 1975a), presumably by the mechanism of insertion of the drug molecule into the double helix of DNA, as has been demonstrated for daunorubicin (Ward et al, 1965;Pigram et al, 1972;Phillips et al, 1978).…”

A Theoretical Investigation on the Sequence Selective Binding of Daunomycin to Double-Stranded Polynucleotides

“…We shall mention here only some of the most representative results. Early (1978) thermal denaturation studies, spectrophotometric analysis and inhibition of polymerisation reactions indicated equal binding affinities of DNM for poly(dG-dC)·poly(dG-dC) and poly(dA-dT)·poly(dA-dT) but a significantly greater affinity for these alternating copolymers than for the poly(dA)·poly(dT) homopolymer (7). Competition dialysis experiments (8) indicated a preference of DNM for rich DNA's and were originally interpreted as indicating a preference of DNM for the G-C base pair.…”