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Polyphosphate Reverses the Toxicity of the Quasi-Enzyme Bleomycin on Alveolar Endothelial Lung Cells In Vitro. Cancers (Basel) 2021; 13:cancers13040750. [PMID: 33670189 PMCID: PMC7916961 DOI: 10.3390/cancers13040750] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/03/2021] [Accepted: 02/09/2021] [Indexed: 12/11/2022] Open
Abstract
The anti-cancer antitumor antibiotic bleomycin(s) (BLM) induces athyminic sites in DNA after its activation, a process that results in strand splitting. Here, using A549 human lung cells or BEAS-2B cells lunc cells, we show that the cell toxicity of BLM can be suppressed by addition of inorganic polyphosphate (polyP), a physiological polymer that accumulates and is released from platelets. BLM at a concentration of 20 µg ml-1 causes a decrease in cell viability (by ~70%), accompanied by an increased DNA damage and chromatin expansion (by amazingly 6-fold). Importantly, the BLM-caused effects on cell growth and DNA integrity are substantially suppressed by polyP. In parallel, the enlargement of the nuclei/chromatin in BLM-treated cells (diameter, 20-25 µm) is normalized to ~12 µm after co-incubation of the cells with BLM and polyP. A sequential application of the drugs (BLM for 3 days, followed by an exposure to polyP) does not cause this normalization. During co-incubation of BLM with polyP the gene for the BLM hydrolase is upregulated. It is concluded that by upregulating this enzyme polyP prevents the toxic side effects of BLM. These data might also contribute to an application of BLM in COVID-19 patients, since polyP inhibits binding of SARS-CoV-2 to cellular ACE2.
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Murray V, Chen JK, Chung LH. The Interaction of the Metallo-Glycopeptide Anti-Tumour Drug Bleomycin with DNA. Int J Mol Sci 2018; 19:E1372. [PMID: 29734689 PMCID: PMC5983701 DOI: 10.3390/ijms19051372] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 11/17/2022] Open
Abstract
The cancer chemotherapeutic drug, bleomycin, is clinically used to treat several neoplasms including testicular and ovarian cancers. Bleomycin is a metallo-glycopeptide antibiotic that requires a transition metal ion, usually Fe(II), for activity. In this review, the properties of bleomycin are examined, especially the interaction of bleomycin with DNA. A Fe(II)-bleomycin complex is capable of DNA cleavage and this process is thought to be the major determinant for the cytotoxicity of bleomycin. The DNA sequence specificity of bleomycin cleavage is found to at 5′-GT* and 5′-GC* dinucleotides (where * indicates the cleaved nucleotide). Using next-generation DNA sequencing, over 200 million double-strand breaks were analysed, and an expanded bleomycin sequence specificity was found to be 5′-RTGT*AY (where R is G or A and Y is T or C) in cellular DNA and 5′-TGT*AT in purified DNA. The different environment of cellular DNA compared to purified DNA was proposed to be responsible for the difference. A number of bleomycin analogues have been examined and their interaction with DNA is also discussed. In particular, the production of bleomycin analogues via genetic manipulation of the modular non-ribosomal peptide synthetases and polyketide synthases in the bleomycin gene cluster is reviewed. The prospects for the synthesis of bleomycin analogues with increased effectiveness as cancer chemotherapeutic agents is also explored.
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Affiliation(s)
- Vincent Murray
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Jon K Chen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
| | - Long H Chung
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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Chung LH, Murray V. The mitochondrial DNA sequence specificity of the anti-tumour drug bleomycin using end-labeled DNA and capillary electrophoresis and a comparison with genome-wide DNA sequencing. J Chromatogr B Analyt Technol Biomed Life Sci 2016; 1008:87-97. [DOI: 10.1016/j.jchromb.2015.11.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 11/17/2015] [Accepted: 11/17/2015] [Indexed: 11/30/2022]
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Giroux RA, Hecht SM. Characterization of Bleomycin Cleavage Sites in Strongly Bound Hairpin DNAs. J Am Chem Soc 2010; 132:16987-96. [DOI: 10.1021/ja107228c] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rachel A. Giroux
- Center for BioEnergetics, Biodesign Institute and Department of Chemistry, Arizona State University, Tempe, Arizona 85287, United States
| | - Sidney M. Hecht
- Center for BioEnergetics, Biodesign Institute and Department of Chemistry, Arizona State University, Tempe, Arizona 85287, United States
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Ma Q, Akiyama Y, Xu Z, Konishi K, Hecht SM. Identification and Cleavage Site Analysis of DNA Sequences Bound Strongly by Bleomycin. J Am Chem Soc 2009; 131:2013-22. [DOI: 10.1021/ja808629s] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Qian Ma
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Yoshitsugu Akiyama
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Zhidong Xu
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Kazuhide Konishi
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Sidney M. Hecht
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22904
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Crystal structure of DNA-bound Co(III) bleomycin B2: Insights on intercalation and minor groove binding. Proc Natl Acad Sci U S A 2008; 105:5052-6. [PMID: 18362349 DOI: 10.1073/pnas.0708143105] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bleomycins constitute a widely studied class of complex DNA cleaving natural products that are used to treat various cancers. Since their first isolation, the bleomycins have provided a paradigm for the development and discovery of additional DNA-cleaving chemotherapeutic agents. The bleomycins consist of a disaccharide-modified metal-binding domain connected to a bithiazole/C-terminal tail via a methylvalerate-Thr linker and induce DNA damage after oxygen activation through site-selective cleavage of duplex DNA at 5'-GT/C sites. Here, we present crystal structures of two different 5'-GT containing oligonucleotides in both the presence and absence of bound Co(III).bleomycin B(2). Several findings from our studies impact the current view of bleomycin binding to DNA. First, we report that the bithiazole intercalates in two distinct modes and can do so independently of well ordered minor groove binding of the metal binding/disaccharide domains. Second, the Co(III)-coordinating equatorial ligands in our structure include the imidazole, histidine amide, pyrimidine N1, and the secondary amine of the beta aminoalanine, whereas the primary amine acts as an axial ligand. Third, minor groove binding of Co(III).bleomycin involves direct hydrogen bonding interactions of the metal binding domain and disaccharide with the DNA. Finally, modeling of a hydroperoxide ligand coordinated to Co(III) suggests that it is ideally positioned for initiation of C4'-H abstraction.
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Sergeyev DS, Zarytova VF. Interaction of bleomycin and its oligonucleotide derivatives with nucleic acids. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1996v065n04abeh000216] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Cagir A, Tao ZF, Sucheck SJ, Hecht SM. Solid-phase synthesis and biochemical evaluation of conformationally constrained analogues of deglycobleomycin A5. Bioorg Med Chem 2003; 11:5179-87. [PMID: 14604681 DOI: 10.1016/j.bmc.2003.08.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Deglycobleomycin binds to and degrades the self-complementary oligonucleotide d(CGCTAGCG)(2) in a sequence selective fashion. A previous modeling study [J. Am. Chem. Soc. 120, (1998), 7450] had shown that, during binding to double stranded DNA, the conformation of the methylvalerate domain of deglycoBLM approximated that of S-proline. In the belief that an analogue of deglycoBLM structurally constrained to mimic the DNA-bound conformation might exhibit facilitated DNA binding and cleavage, an analogue of deglycoBLM was prepared in which the methylvalerate moiety was replaced by S-proline. This deglycoBLM analogue, as well as the related analogue containing R-proline, was synthesized on a TentaGel resin. Both of the analogues were found to be capable of binding Fe(2+) and activating O(2) for transfer to styrene. However, both deglycoBLM analogues exhibited diminished abilities to effect the relaxation of supercoiled plasmid DNA, and neither mediated sequence selective DNA cleavage.
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Affiliation(s)
- Ali Cagir
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, VA 22901, USA
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Rishel MJ, Thomas CJ, Tao ZF, Vialas C, Leitheiser CJ, Hecht SM. Conformationally constrained analogues of bleomycin A5. J Am Chem Soc 2003; 125:10194-205. [PMID: 12926941 DOI: 10.1021/ja030057w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bleomycin (BLM) group antitumor antibiotics are glycopeptide-derived natural products shown to cause sequence selective lesions in DNA. Prior studies have indicated that the linker region, composed of the methylvalerate and threonine residues, may be responsible for a conformational bend in the agent required for efficient DNA cleavage. We have synthesized a number of conformationally constrained methylvalerate analogues and incorporated them into deglycobleomycin A(5) congeners using our recently reported procedure for the solid phase construction of (deglyco)bleomycin and its analogues. These analogues were designed to probe the effects of conformational constraint of the native valerate moiety. Initial experiments indicated that the constrained molecules, none of which mimic the conformation proposed for the natural valerate linker, possessed DNA cleavage activity, albeit with potencies less than that of (deglyco)BLM and lacking sequence selectivity. Further experiments demonstrated that these analogues failed to produce alkali-labile lesions in DNA or sequence selective oxidative damage in RNA. However, two of the conformationally constrained deglycoBLM analogues were shown to mediate RNA cleavage in the absence of added Fe(2+). The ability of the analogues to mediate the oxygenation of small molecules was also assayed, and it was shown that they were as competent in the transfer of oxygen to low molecular weight substrates as the parent compound.
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Affiliation(s)
- Michael J Rishel
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA
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Hecht SM. Bleomycin: new perspectives on the mechanism of action. JOURNAL OF NATURAL PRODUCTS 2000; 63:158-168. [PMID: 10650103 DOI: 10.1021/np990549f] [Citation(s) in RCA: 409] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The bleomycin group antitumor antibiotics have long been of interest as a consequence of their efficacy in the treatment of certain tumors, not to mention their unique structures and properties in mediating dioxygen activation and sequence selective degradation of DNA. At a chemical level, the structure originally assigned to bleomycin was subsequently reassigned and the new structure has been confirmed by total synthesis. Through the elaboration of structurally modified bleomycin congeners and fragments, synthetic efforts have also facilitated an understanding of the contribution of individual structural domains in bleomycin to sequence selective DNA binding and cleavage, and have also provided insights into the nature of the chemical processes by which DNA degradation takes place. Within the last several years, it has also become apparent that bleomycin can mediate the oxidative degradation of all major classes of cellular RNAs; it seems entirely plausible that RNA may also represent an important locus of action for this class of antitumor agent. In parallel with ongoing synthetic and mechanistic efforts using classical methods, the study of bleomycins attached to solid supports has been shown to provide important mechanistic insights, and the actual elaboration of modified bleomycins by solid phase synthesis constitutes a logical extension of such efforts.
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Affiliation(s)
- S M Hecht
- Departments of Chemistry and Biology, University of Virginia, Charlottesville, Virginia 22901, USA.
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11
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Claussen CA, Long EC. Nucleic Acid recognition by metal complexes of bleomycin. Chem Rev 1999; 99:2797-816. [PMID: 11749501 DOI: 10.1021/cr980449z] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C A Claussen
- Department of Chemistry, Purdue School of Science, Indiana University Purdue University-Indianapolis, Indianapolis, Indiana 46202-3274
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13
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Zuber G, Quada JC, Hecht SM. Sequence Selective Cleavage of a DNA Octanucleotide by Chlorinated Bithiazoles and Bleomycins. J Am Chem Soc 1998. [DOI: 10.1021/ja981937r] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Guy Zuber
- Departments of Chemistry and Biology University of Virginia, Charlottesville, Virginia 22901
| | - James C. Quada
- Departments of Chemistry and Biology University of Virginia, Charlottesville, Virginia 22901
| | - Sidney M. Hecht
- Departments of Chemistry and Biology University of Virginia, Charlottesville, Virginia 22901
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Stubbe J, Kozarich JW, Wu W, Vanderwall DE. Bleomycins: A Structural Model for Specificity, Binding, and Double Strand Cleavage. Acc Chem Res 1996. [DOI: 10.1021/ar9501333] [Citation(s) in RCA: 189] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- JoAnne Stubbe
- Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065-0900
| | - John W. Kozarich
- Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065-0900
| | - Wei Wu
- Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065-0900
| | - Dana E. Vanderwall
- Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065-0900
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15
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Mao Q, Fulmer P, Li W, DeRose EF, Petering DH. Different conformations and site selectivity of HO-2-Co(III)-bleomycin A2 and Co (III)-bleomycin A2 bound to DNA oligomers. J Biol Chem 1996; 271:6185-91. [PMID: 8626408 DOI: 10.1074/jbc.271.11.6185] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Conformational properties of HO2(-)-Co(III)-bleomycin A2 (Form I) and Co(III)-bleomycin (Form II) bound to DNA oligomers offering either principal cleavage site for the drug, d(GGAAGCTTCC)2 or d(AAACGTIT)2, have been studied by NMR methods. Form I binds in slow exchange to these oligomers. It retains most of its solution nuclear Overhauser effects (NOEs) upon binding to either oligomer. Pyrimidinyl methyl protons from the metal domain of the drug make an NOE connection with a G5 2-amino proton on DNA. The bithiazole intercalates between base pairs involving either C6 and T7 or T6 and T7 of the two DNA molecules, according to NOE connections between the bithiazole protons and protons from these bases and changes in the positions of their chemical shifts. Form II also retains most of its solution NOEs upon association with the first oligomer. However, in contrast to Form I it binds to DNA in fast exchange on the NMR time scale over the temperature range of 5-35 degrees C and does not break the degeneracy of the DNA proton chemical shifts. No intermolecular NOEs between Form II and the 10-mer have been detected. Likewise, the major perturbation in chemical shift of the histidine H2 and guanine G5 protons seen in Form I-DNA adducts is absent in Form II-DNA. The association constant of Form II with d(GGAAGCTTCC)2 in 20 mM HEPES buffer at pH 7.4 and 25 degrees C is 1.7 x 10(5) M(-1), and 1.0 mol of Form II bind per mol of 10-mer.
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Affiliation(s)
- Q Mao
- Department of Chemistry, University of Wisconsin, Milwaukee 53201, USA
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16
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Wu W, Vanderwall DE, Lui SM, Tang XJ, Turner CJ, Kozarich JW, Stubbe J. Studies of Co·Bleomycin A2 Green: Its Detailed Structural Characterization by NMR and Molecular Modeling and Its Sequence-Specific Interaction with DNA Oligonucleotides. J Am Chem Soc 1996. [DOI: 10.1021/ja9524964] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei Wu
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Dana E. Vanderwall
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Siu Man Lui
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Xue-Jun Tang
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Christopher J. Turner
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - John W. Kozarich
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - JoAnne Stubbe
- Contribution from the Departments of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
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Nightingale KP, Fox KR. Light-activated cleavage of DNA by cobalt-bleomycin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 220:173-81. [PMID: 7509745 DOI: 10.1111/j.1432-1033.1994.tb18612.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have studied the light-activated cleavage of DNA by cobalt-bleomycin using a series of synthetic DNA fragments containing (AT)n and (GC)n. This cleavage reaction requires high concentrations of the antibiotic and appears to be a stoichiometric process rather than a catalytic process. We find that, in common with the iron-complex, cobalt-bleomycin can cleave at ApT steps within regions of alternating AT residues; ApT steps within other sequences including (AAT)n. (ATP)n are not good substrates for cobalt-bleomycin cleavage. Some repetitive regions display an alternating pattern of cleavage products, revealing the preferred arrangement of ligand molecules along a saturated DNA lattice. A similar repetitive pattern is found for diethylpyrocarbonate modification and hydroxyl-radical cleavage. Although cleavage of ApT and GpC proceeds at equivalent rates, the data suggest that bleomycin binds more tightly to the latter. Adenine residues on the 3' side of both GpC-cleavage and ApT-cleavage sites are rendered more reactive to diethylpyrocarbonate, consistent with a ligand-induced alteration in local DNA structure. The cobalt-bleomycin-binding site consists of not more than four base pairs, and may be as small as three base pairs.
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Affiliation(s)
- K P Nightingale
- Department of Physiology and Pharmacology, University of Southampton, England
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18
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Abstract
Genetic and related effects of cobalt compounds are reviewed and discussed with respect to mechanisms. In prokaryotic assays, Co(II) salts generally are nonmutagenic. In Saccharomyces cerevisiae, CoCl2 is mutagenic to mitochondrial genes and weakly mutagenic or nonmutagenic to chromosomal genes. In plants, Co(II) salts induced gene mutations and chromosomal aberrations. In mammalian cells in vitro, Co(II) compounds caused DNA strand breaks, sister-chromatid exchanges and aneuploidy, but not chromosomal aberrations. In two cell lines, CoCl2 was weakly mutagenic. Interestingly, the poorly soluble compound CoS caused DNA strand breaks and morphological transformation of mammalian cell lines. In contrast to its weak clastogenic and mutagenic properties, cobalt(II) exerts pronounced antimutagenicity in bacteria and mostly comutagenic effects in mammalian cells. In Escherichia coli CoCl2 lowered the frequency of mutations induced by MNNG, uv or X rays. In Chinese hamster V79 cells, CoCl2 enhanced the mutagenicity and clastogenicity of uv light but not of gamma rays. Regarding direct genotoxic mechanisms, Co(II) induces the formation of reactive oxygen species when combined with hydrogen peroxide in cell-free systems. At high (i.e., millimolar) concentrations, Co(II) also decreases the fidelity of DNA synthesis. Regarding anti- and co-mutagenic mechanisms, evidence for the interference of Co(II) with DNA repair processes is discussed. These mechanisms are regarded as relevant for the risk assessment of human exposure to cobalt in combination with other agents.
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Affiliation(s)
- D Beyersmann
- Department of Biology and Chemistry, University of Bremen, Germany
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Affiliation(s)
- E Palecek
- Institute of Biophysics, Czechoslovak Academy of Sciences, Brno
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Abstract
The DNA double helix exhibits local sequence-dependent polymorphism at the level of the single base pair and dinucleotide step. Curvature of the DNA molecule occurs in DNA regions with a specific type of nucleotide sequence periodicities. Negative supercoiling induces in vitro local nucleotide sequence-dependent DNA structures such as cruciforms, left-handed DNA, multistranded structures, etc. Techniques based on chemical probes have been proposed that make it possible to study DNA local structures in cells. Recent results suggest that the local DNA structures observed in vitro exist in the cell, but their occurrence and structural details are dependent on the DNA superhelical density in the cell and can be related to some cellular processes.
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Affiliation(s)
- E Palecek
- Max-Planck Institut für Biophysikalische Chemie, Göttingen, BRD
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Abstract
An overview of the chemical and photochemical probes which over the past ten years have been used in studies of DNA/ligand complexes and of non-B-form DNA conformations is presented with emphasis on the chemical reactions of the probes with DNA and on their present 'use-profile'. The chemical probes include: dimethyl sulfate, ethyl nitroso urea, diethyl pyrocarbonate, osmium tetroxide, permanganate, aldehydes, methidiumpropyl-EDTA-Fell (MPE), phenanthroline metal complexes and EDTA/FeII. The photochemical probes that have been used include: psoralens, UVB, acridines and uranyl salts. The biological systems analysed by use of these probes are reviewed by tabulation.
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Affiliation(s)
- P E Nielsen
- Department of Biochemistry B, Panum Institute, University of Copenhagen, Denmark
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Strekowski L, Harden DB, Wydra RL, Stewart KD, Wilson WD. Molecular basis for potentiation of bleomycin-mediated degradation of DNA by polyamines. Experimental and molecular mechanical studies. J Mol Recognit 1989; 2:158-66. [PMID: 2484026 DOI: 10.1002/jmr.300020404] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The bleomycin-mediated degradation of DNA is stimulated (amplified) by certain DNA binding compounds, such as polyamines, that distort the double helix. Computer modelling studies suggest that putrescine (1), spermidine (2), and spermine (3) bind preferentially on the floor of the major groove of (dGdC)5.(dGdC)5. This interaction results in a bend of the oligomer helix toward the major groove and enlargement of the minor groove, both effects being in the order 1 less than 2 less than 3. These polyamine-induced distortions, as obtained from theoretical studies, parallel the experimental values of the amplification activities of 1-3 in the bleomycin-mediated degradation of poly(dGdC).poly(dGdC). The amplification mechanism of non-competitive binding of amplifier molecules in the major groove, and bleomycin in the minor groove, is proposed. It is suggested that the amplifier-induced conformational changes of the DNA helix increase affinity of the activated bleomycin complex toward the DNA minor groove and, consequently, result in an increased efficiency of the bleomycin-mediated degradation of the helix.
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Affiliation(s)
- L Strekowski
- Department of Chemistry, Georgia State University, Atlanta 30303
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