Binding of bleomycin to DNA: intercalation of the bithiazole rings

Povirk, Lawrence F.; Hogan, Michael E.; Dattagupta, Nanibhushan

doi:10.1021/bi00568a015

Cited by 180 publications

(135 citation statements)

References 39 publications

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“…Whether the bithiazole intercalates between DNA bases or simply binds in the minor groove is questionable. The coplanarity of the bithiazole rings (11) and their parallelism to the aromatic rings of DNA bases (12) are in favour of an intercalation process such as already suggested by Murakami (13) on the basis of model studies.…”

Section: Introductionmentioning

confidence: 75%

Is the bithiazole moiety of bleomycin a classical intercalator?

Hénichart¹,

Bernier²,

Helbecque³

et al. 1985

Nucl Acids Res

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Bleomycin is a widespread anticancerous drug, the biological activity of which having been extensively studied. Its metal ion-chelating portion has been shown to cleave DNA whereas the role of the bithiazole moiety is still questionable. In order to elucidate this problem some 2',4-disubstituted bithiazoles structurally related to the "tripeptide S" moiety of bleomycin were synthesized and their interaction with DNA was studied using 4Tm, fluorescence, EPR and viscometry techniques. The results of ATm and fluorescence quenching determinations were in favour of a binding of the bithiazole part by an intercalation process. Nevertheless, the use of the spin-label probes indicated only a partial intercalation of the ring between the base-pairs. Moreover, viscometry data which clearly exhibited a slight decrease of DNA length in the presence of bithiazole derivative led to the proposal of a binding model involving a partial insertion of a thiazole ring which wedges in between the bases at a bending point of DNA.

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Section: Introductionmentioning

confidence: 75%

Is the bithiazole moiety of bleomycin a classical intercalator?

Hénichart¹,

Bernier²,

Helbecque³

et al. 1985

Nucl Acids Res

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“…They stabilize base pairs, lengthen and stiffen the helix, and increase the intrinsic viscosity of DNA. An examination of (27). The relative affinity of a molecule for superhelical and relaxed forms of a DNA is a function of its unwinding angle and is given by the relationship (27) Vs/Vr = e-A/kT [1] Reaction time.…”

Section: Methodsmentioning

confidence: 99%

“…An examination of (27). The relative affinity of a molecule for superhelical and relaxed forms of a DNA is a function of its unwinding angle and is given by the relationship (27) Vs/Vr = e-A/kT [1] Reaction time. min 0 2 4 6 8 10 in which 0 is the unwinding angle, A is the torsional free energy change per degree of unwinding, k is the Boltzmann constant, T is the absolute temperature, and vP/V7 is the partition of the molecule between superhelical and relaxed forms of DNA.…”

Section: Methodsmentioning

confidence: 99%

DNA alkylation and unwinding induced by benzo[a]pyrene diol epoxide: modulation by ionic strength and superhelicity.

Gamper¹,

Straub²,

Calvin³

et al. 1980

Proc. Natl. Acad. Sci. U.S.A.

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Superhelical and partially relaxed DNAs of simian virus 40 were allowed to react in vitro with (1)7#,8a-dihydroxy-9a, 8,9, [3H]BaP diol epoxide, 1.5 mg/ml in 19:1 (vol/vol) tetrahydrofuran/triethylamine, was also synthesized according to published procedures (12). It had a specific activity of 1.23 Ci/mmol (1 Ci = 3.7 X 1010 becquerels). The BaP diol epoxide stocks were stored at -70'C and dilutions were made with dimethyl sulfoxide. SV40 DNA. Superhelical (form I) SV40 DNA was isolated from infected TC-7 African green monkey cells by a modification of the Hirt extraction essentially as described by Hallick et al. DNA Alkylation and Adduct Characterization. SV40 DNA was modified with BaP diol epoxide in 20 mM Tris-HCl (pH 8.0)/0.5 mM EDTA/10% (vol/vol) dimethyl sulfoxide at the indicated molar reaction ratios (BaP diol epoxide to DNA mononucleotide). Reaction mixtures were incubated in the dark at 370C for at least 90 min. Alkylation was quantified by radioactivity counting, using SV40 [14C]DNA and [3H]BaP diol epoxide. The modified DNA was diluted to 1.0 ml with 20 mM Tris-HCl (pH 8.0)/0.5 mM EDTA/0.5 M NaCI and extracted three times with 1.0 ml of ethyl acetate. After addition of 30 ,ug of carrier calf thymus DNA (Sigma), the DNA was precipitated from the aqueous phase by addition of 2.0 ml of NaClsaturated ethanol and by storage overnight at -20°C. The DNA was pelleted, washed, and resuspended in 1.0 ml of NaCl-saturated 70% (vol/vol) ethanol. It was then collected on a Millipore 0.45-,um-pore-diameter HAWP filter, combusted, and assayed for radioactivity. Binding data were calculated by assuming SV40 DNA contains 5200 base pairs (14) and has a molecular weight of 3.6 X 106(15).Hydrocarbon adducts, enzymatically released from alkylated DNA, were isolated by Sephadex LH-20 chromatography and further resolved by high-pressure liquid chromatography as described by Straub et al. (8).Gel Electrophoresis. Vertical 1.4% agarose (Bio-Rad) slab gels (13.3 X 13.0 X 0.5 cm) were prepared and run in 40 mM Tris-HCl (pH 7.9)/5 mM sodium acetate/i mM EDTA at 50 V for [12][13][14][15][16] hr. Composite 2% polyacrylamide/0.5% agarose Abbreviations: BaP diol epoxide, 8,9, SV40, simian virus 40.

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“…5 The drug acts as an antitumor agent by virtue of the ability of a metal complex of the antibiotic to cleave DNA. [6][7][8][9][10] The overall structure of this agent can be thought of as containing four distinct regions ( Figure 1): the metalbinding domain, which is responsible for metal binding, 11,12 oxygen activation 8,11,13,14 and site-selective DNA cleavage; 12,15 the peptide linker; the DNA binding domain, containing a bithiazole moiety, which provides the majority of the DNA binding affinity, 7,16 and the disaccharide moiety, which may influence metal ion binding. 12,[17][18][19][20][21][22][23][24] With the aim of establishing structure-function correlations, much research has been devoted to the elucidation of the three-dimensional structures of some metallo-BLMs.…”

Section: Introductionmentioning

confidence: 99%

Possible structural role of the disaccharide unit in Fe-bleomycin before and after oxygen activation

Lehmann

2011

J Antibiot

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Our previous investigation of the solution structure of Fe(II)-bleomycin pointed toward the carbamoyl group in the mannose moiety or a water molecule as possible alternative axial ligands to the metal center in this metallo-bleomycin. The possibility of a solvent molecule occupying the apical position trans to the primary amine has not been ruled out yet. In order to explore this possibility even further, the coordination chemistry of azide-bound Fe(II)-bleomycin was investigated with the use of NMR applied to paramagnetic molecules. Fe(II)-and apo-bleomycin were also re-visited. Comparison of the NMR results for both Fe(II)-bound molecules obtained in the present study strongly suggests that the carbamoyl oxygen is ligated to Fe(II), and it is released from coordination upon azide binding. This event is suggested based on the diminished paramagnetic character exhibited by the carbohydrate moiety in Fe(II)-azide-bleomycin when compared with its parent metal complex. A possible structural role for the glucopyranose fragment, which changes throughout the process that starts with metallo-bleomycin formation and ends with DNA binding, is discussed. The study of the coordination of azide by Fe(II)-bleomycin through NMR has not been reported previously. Unlike magnetic CD data, NMR offers a residue-by-residue account of the possible structural changes that take place in Fe(II)-bleomycin after azide binding.

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Binding of bleomycin to DNA: intercalation of the bithiazole rings

Cited by 180 publications

References 39 publications

Is the bithiazole moiety of bleomycin a classical intercalator?

Is the bithiazole moiety of bleomycin a classical intercalator?

DNA alkylation and unwinding induced by benzo[a]pyrene diol epoxide: modulation by ionic strength and superhelicity.

Possible structural role of the disaccharide unit in Fe-bleomycin before and after oxygen activation

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