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Quintal SM, dePaula QA, Farrell NP. Zinc finger proteins as templates for metal ion exchange and ligand reactivity. Chemical and biological consequences. Metallomics 2011; 3:121-39. [PMID: 21253649 DOI: 10.1039/c0mt00070a] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Zinc finger reactions with inorganic ions and coordination compounds are as diverse as the zinc fingers themselves. Use of metal ions such as Co(2+) and Cd(2+) has given structural, thermodynamic and kinetic information on zinc fingers and zinc-finger-DNA/RNA interactions. It is a general truism that alteration of the coordination sphere in the finger environment will disrupt the recognition with DNA/RNA and this has implications for mechanism of toxicity and carcinogenesis of metal ions. Structural zinc fingers are susceptible to electrophilic attack and the recognition that the coordination sphere of inorganic compounds may be modulated for control of electrophilic attack on zinc fingers raises the possibility of systematic studies of zinc fingers as drug targets using inorganic chemistry. Some inorganic compounds such as those of As(III) and Au(I) may exert their biological effects through inactivation of zinc fingers and novel approaches to specifically attack the zinc-bound ligands using Co(III)-Schiff bases and Platinum(II)-Nucleobase compounds have been proposed. The genomic importance of zinc fingers suggests that the "coordination chemistry" of zinc fingers themselves is ripe for exploration to design new targets for medicinal inorganic chemistry.
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Affiliation(s)
- Susana M Quintal
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA 23284-2006, USA
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2
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Kozelka J. Molecular origin of the sequence-dependent kinetics of reactions between cisplatin derivatives and DNA. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2008.04.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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3
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Almaraz E, de Paula QA, Liu Q, Reibenspies JH, Darensbourg MY, Farrell NP. Thiolate Bridging and Metal Exchange in Adducts of a Zinc Finger Model and PtII Complexes: Biomimetic Studies of Protein/Pt/DNA Interactions. J Am Chem Soc 2008; 130:6272-80. [DOI: 10.1021/ja711254q] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elky Almaraz
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
| | - Queite A. de Paula
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
| | - Qin Liu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
| | - Joseph H. Reibenspies
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
| | - Marcetta Y. Darensbourg
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
| | - Nicholas P. Farrell
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, and Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia, 23284-2006
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4
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Chválová K, Sari MA, Bombard S, Kozelka J. LEF-1 recognition of platinated GG sequences within double-stranded DNA. Influence of flanking bases. J Inorg Biochem 2007; 102:242-50. [PMID: 17961652 DOI: 10.1016/j.jinorgbio.2007.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 08/03/2007] [Accepted: 08/23/2007] [Indexed: 11/30/2022]
Abstract
The lymphoid enhancer-binding factor 1 (LEF-1) recognizes a double-stranded 9 base-pairs (bp) long motif in DNA which is significantly bent upon binding. This bend is centered at two destacked adenines whose geometry closely resembles that of two adjacent guanines crosslinked by the antitumor drug cisplatin. It has been proposed that cisplatin-GG crosslinks could hijack high mobility group (HMG) box containing transcription factors such as LEF-1. In order to examine such a possibility, we used electrophoretic mobility shift assays to determine the affinity of the HMG box of LEF-1 for a series of 25 oligonucleotides containing a central GG sequence, free or site-specifically modified by cisplatin. The binding affinity of the GG-platinated oligonucleotides was 3-6-fold higher than that determined for the corresponding unplatinated oligonucleotides, however, the binding to all cisplatin-modified oligonucleotides was at least 1 order of magnitude weaker than that to the 25 bp oligonucleotide containing the recognition 9 bp motif. The binding affinity was dependent on the nature of bases flanking the cisplatin-crosslinked G(*)G(*) dinucleotide, the AG(*)G(*)T sequence displaying the strongest affinity and CG(*)G(*)T showing the strongest binding enhancement upon platination. In contrast, modification of the AGGT sequence with the third-generation platinum antitumor drug oxaliplatin did not enhance the affinity significantly. These results suggest that the cisplatin-caused bending of DNA does produce a target for LEF-1 binding, however, the cisplatinated DNA does not appear to be a strong competitor for the LEF-1 recognition sequence.
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Affiliation(s)
- Katerina Chválová
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Descartes, UMR 8601 CNRS, 45, rue des Saints-Pères, 75270 Paris, France
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5
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Kaspárková J, Nováková O, Vrána O, Intini F, Natile G, Brabec V. Molecular Aspects of Antitumor Effects of a New Platinum(IV) Drug. Mol Pharmacol 2006; 70:1708-19. [PMID: 16896071 DOI: 10.1124/mol.106.027730] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The new platinum(IV) complex cis,trans,cis-[PtCl(2)(CH(3)COO)(2)-(NH(3))(1-adamantylamine)] [adamplatin(IV)] seems promising for the perspective application in therapy of corresponding tumors. It is therefore of great interest to understand details of mechanisms underlying its biological efficacy. Cellular uptake of the drug, alterations in the target DNA induced by platinum drugs along with processing of platinum-induced damage to DNA and drug inactivation by sulfur-containing compounds belong to major pharmacological factors affecting antitumor effects of platinum compounds. We examined in the present work the significance of these factors in the mechanism of antitumor effects of adamplatin(IV) and compared the results with those of the parallel studies performed with "conventional" cisplatin. The results show that deactivation of adamplatin(IV) by sulfur-containing compounds (such as glutathione or metallothioneins) is likely to play a less significant role in the mechanism of resistance of tumor cells to adamplatin(IV) in contrast to the role of these reactions in the effects of cisplatin. Moreover, the treatment of tumor cells with adamplatin(IV) does not result in DNA modifications that would be markedly different from those produced by cisplatin. In contrast, the effects of other factors, such as enhanced accumulation of the drug in cells, strong inhibition of DNA polymerization by these adducts, lowered DNA repair, and DNA-protein cross-linking are different from the effects of these factors in the mechanism underlying activity of cisplatin. Hence, the differences between effects of adamplatin(IV) and cisplatin observed in the present work on molecular level may help understand the unique activity of adamplatin(IV).
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Affiliation(s)
- Jana Kaspárková
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, CZ-61265 Brno, Czech Republic
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Zorbas H, Keppler BK. Cisplatin damage: are DNA repair proteins saviors or traitors to the cell? Chembiochem 2005; 6:1157-66. [PMID: 15934047 DOI: 10.1002/cbic.200400427] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Haralabos Zorbas
- Max-Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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7
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Liu Q, Golden M, Darensbourg MY, Farrell N. Thiolate-bridged heterodinuclear platinum–zinc chelates as models for ternary platinum–DNA–protein complexes and zinc ejection from zinc fingers. Evidence from studies using ESI-mass spectrometry. Chem Commun (Camb) 2005:4360-2. [PMID: 16113748 DOI: 10.1039/b507751f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structures for model ternary platinum-DNA-protein complexes and zinc ejection from zinc fingers by platinum were deduced from the ESI-MS spectra of the interaction of model Zn and Pt complexes.
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Affiliation(s)
- Qin Liu
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
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Kloster M, Kostrhunova H, Zaludova R, Malina J, Kasparkova J, Brabec V, Farrell N. Trifunctional Dinuclear Platinum Complexes as DNA−Protein Cross-Linking Agents. Biochemistry 2004; 43:7776-86. [PMID: 15196020 DOI: 10.1021/bi030243e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The trifunctional dinuclear platinum compounds 1,2/c,c [[cis-PtCl(NH(3))(2)]mu-H(2)N(CH(2))(6)NH(2)[cis-PtCl(2)(NH(3))]](+) and 1,2/t,c [[trans-PtCl(NH(3))(2)]mu-H(2)N(CH(2))(6)NH(2)[cis-PtCl(2)(NH(3))]](+) contain a monofunctional platinum coordination sphere linked to a cis-[PtCl(2)(amine)(2)] moiety. The compounds have been examined for their DNA binding and ability to induce covalent ternary DNA-protein cross-links. Comparison was made with representative bifunctional dinuclear platinum compounds [[PtCl(NH(3))(2)](2)mu-H(2)N(CH(2))(n)NH(2)](2+). DNA modified by the trifunctional compounds is able to bind and cross-link BamHI, a sequence-specific DNA-binding protein that recognizes the palindromic sequence GGATCC and also very efficiently binds and cross-links SP1, a sequence-specific Zn finger protein that induces a bend in the DNA upon binding. Two representative nonsequence-specific DNA-binding proteins, the Klenow fragment from DNA polymerase I and Klenow exonuclease minus (which has been mutated to remove the 3'-5' proofreading domain), both bind modified DNA and effectively cross-link to the DNA. Data from circular dichroism, inhibition of ethidium bromide fluorescence, interstrand cross-linking and unwinding assays are all consistent with (Pt,Pt) interstrand cross-links as the dominant lesion of trifunctional compounds and the most likely structure to form the ternary DNA-protein cross-links. In vitro transcription of RNA is inhibited by the platinum compounds and indicate G residues as primary binding sites. Binding to calf thymus DNA as assessed by differential pulse polarography is rapid and essentially quantitative. An increase in melting temperature of CT DNA adducted by the platinum compounds is observed at low salt concentrations but at high salt, modification results in a decrease of t(m). In summary, the trifunctional agents may find use as protein-targeting drugs and as probes for conformational effects on DNA-protein interactions.
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Affiliation(s)
- Miriam Kloster
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, Richmond, Virginia 23284-2006, USA
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9
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Monjardet-Bas V, Bombard S, Chottard JC, Kozelka J. GA and AG sequences of DNA react with cisplatin at comparable rates. Chemistry 2004; 9:4739-45. [PMID: 14566881 DOI: 10.1002/chem.200305085] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The sequence selectivity of the antitumor drug cisplatin (cis-[PtCl(2)(NH(3))(2)] (1)) between the 5'-AG-3' and 5'-GA-3' sites of DNA has been a matter of discussion for more than twenty years. In this work, we compared the reactivity of GA and AG sequences of DNA towards the aquated forms of cisplatin (cis-[PtCl(NH(3))(2)(H(2)O)](+) (2), cis-[Pt(NH(3))(2)(H(2)O)(2)](2+) (3), and cis-[Pt(OH)(NH(3))(2)(H(2)O)](+) (4)) using two sets of experiments. In the first, we investigated a DNA hairpin, whose duplex stem contained a TGAT sequence as the single reactive site, and determined the individual rate constants of platination with 2 and 3 for G and A in acidic solution. The rate constants at 20 degrees C in 0.1M NaClO(4) at pH 4.5+/-0.1 were 0.09(4) M(-1)s(-1) (G) and 0.11(3) M(-1)s(-1) (A) for 2, and 9.6(1) M(-1)s(-1) (G) and 1.7(1) M(-1)s(-1) (A) for 3. These values are similar to those obtained previously for an analogous hairpin that contained a TAGT sequence. The monoadducts formed with 2 by both GA purines are extremely long-lived, partly as a result of the slow hydrolysis of the chloro monoadduct at A, and partly because of the very low chelation rate (1.4 x 10(-5)s(-1) at 20 degrees C) of the aqua monoadduct on the guanine. In the second set of experiments, we incubated pure or enriched samples of 1, 2, 3, or 4 for 18-64 h at 25 degrees C with a 19 base pair (bp) DNA duplex, whose radiolabeled top strand contained one GA and one AG sequence as the only reactive sites. Quantification of the number of GA and AG cross-links afforded a ratio of about two in favor of AG, irrespective of the nature of the leaving ligands. These results disagree with a previous NMR spectroscopy study, and indicate that GA sequences of DNA are substantially more susceptible to attack by cisplatin than previously thought.
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Affiliation(s)
- Véronique Monjardet-Bas
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, CNRS, UMR 8601, 45 rue des Saints-Pères, 75270 Paris, France
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Temple MD, McFadyen WD, Holmes RJ, Denny WA, Murray V. Interaction of cisplatin and DNA-targeted 9-aminoacridine platinum complexes with DNA. Biochemistry 2000; 39:5593-9. [PMID: 10820033 DOI: 10.1021/bi9922143] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interaction of acridine- and 9-aminoacridinecarboxamide platinum complexes with DNA was investigated with respect to their DNA sequence specificity and kinetics of binding. The DNA sequence specificity of the compounds was quantitatively analyzed using a polymerase stop assay with the plasmid pUC19. The 9-aminoacridinecarboxamide platinum complexes exhibited a different sequence specificity to that of cisplatin, shifted away from runs of consecutive guanines (the main binding site for cisplatin). This alteration was dependent on chain length. Shorter chain length compounds (n = 2, 3) showed a greater difference in sequence specificity, while longer chain length compounds (n = 4, 5) more closely resembled cisplatin. An acridinecarboxamide platinum complex showed a similar sequence specificity to cisplatin, revealing that the major change of sequence specificity was due to the presence of the 9-amino substituent. A linear amplification system was used to investigate the time course of the reaction. The presence of an intercalating group (acridinecarboxamide or 9-aminoacridinecarboxamide) greatly increased the rate of reaction with DNA; this is proposed to be due to a different reaction mechanism with DNA (direct displacement by the N-7 of guanine).
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Affiliation(s)
- M D Temple
- School of Biochemistry and Molecular Genetics, University of New South Wales, Sydney, New South Wales 2052, Australia
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Whittaker J, McFadyen WD, Wickham G, Wakelin LP, Murray V. The interaction of DNA-targeted platinum phenanthridinium complexes with DNA. Nucleic Acids Res 1998; 26:3933-9. [PMID: 9705500 PMCID: PMC147812 DOI: 10.1093/nar/26.17.3933] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cisplatin analogues were synthesised that consisted of platinum(II) diamine complexes tethered via a polymethylene chain ( n = 3, 5, 8 and 10) to a phenanthridinium cation. Both chloro and iodo leaving groups were examined. DNA adduct formation was quantitatively analysed using a linear amplification system with the plasmid pGEM-3Zf(+). This system utilised Taq DNA polymerase to extend from an oligonucleotide primer to the damage site. This damage site inhibited the extension of the DNA polymerase. The products were electrophoresed on a DNA sequencing gel enabling adduct formation to be determined at base pair resolution. The damage intensity at each site was determined by densitometry. The platinum phenanthridinium complexes were shown to damage DNA at shorter incubation times than cisplatin. To produce similar levels of damage, an 18 h incubation was required for cisplatin compared to 30 min for the n = 3 platinum phenanthridinium complexes; this indicates that the intercalating chromophore causes a large increase in the rate of platination. A reaction mechanism involving direct displacement of the chloride by the N-7 of guanine may account for the rate increase. These results indicate that further development of these compounds could lead to more effective cancer chemotherapeutic agents.
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Affiliation(s)
- J Whittaker
- School of Biochemistry and Molecular Genetics and School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
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12
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Reeder F, Guo Z, Murdoch PD, Corazza A, Hambley TW, Berners-Price SJ, Chottard JC, Sadler PJ. Platination of a GG site on single-stranded and double-stranded forms of a 14-base oligonucleotide with diaqua cisplatin followed by NMR and HPLC -- influence of the platinum ligands and base sequence on 5'-G versus 3'-G platination selectivity. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 249:370-82. [PMID: 9370343 DOI: 10.1111/j.1432-1033.1997.00370.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Detailed studies of the kinetics of platination of the single-stranded 14-base DNA oligonucleotide d(ATACATGGTACATA) and the corresponding duplex by cis-[Pt(NH3)2(H2O)2]2+ show that HPLC and NMR are complementary methods which provide similar results. The 5'-G and 3'-G monofunctional intermediates were trapped, separated and characterized by NMR (via 15NH3 labeling) and enzymatic digestion followed by mass spectrometry. The kinetic data are compared with those for the corresponding reactions of cis-[PtCl2(NH3)2] (cisplatin) and its monohydrolysed analogue. For both single and double strands of the oligonucleotide, the aqua complex shows little selectivity for the 5'-G or the 3'-G in the initial platination step, whereas the chloro-complex preferentially platinates the 3'-G. The base on the 3' side of the GG sequence appears to play an important role in controlling this selectivity; replacement of T by C increases the selectivity of duplex platination by the diaqua complex by a factor of about 6, and the selectivity of chelation of the 3'-G monofunctional adduct by a factor of about 3. In general the reactivity of the 5'-G in a GG sequence appears to be enhanced in a duplex compared with a single-strand. For both the aqua-monoadduct and chloro-monoadduct, cis-[Pt(NH3)2(N7G)(H2O or Cl)], the 5'-G monoadduct is much longer lived (t1/2 approximately 4 h at 288 K for aqua, 80 h at 298 K for chloro) than the 3'-G monoadduct (t1/2 < or = 45 min at 288 K for aqua, 6 h at 298 K for chloro). Inspection of molecular mechanics models of the end states of various monofunctional adducts provided insight into H-bonding and destacking interactions in these adducts and the sequence selectivity observed in their formation. Such adducts may play an important role in the mechanism of action of platinum anticancer drugs.
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Affiliation(s)
- F Reeder
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, Paris, France
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Bierbach U, Farrell N. Modulation of Nucleotide Binding of trans Platinum(II) Complexes by Planar Ligands. A Combined Proton NMR and Molecular Mechanics Study. Inorg Chem 1997; 36:3657-3665. [PMID: 11670057 DOI: 10.1021/ic970154o] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nonclassical trans platinum complexes containing planar nitrogen bases show biological activity different from that of trans-diamminedichloroplatinum(II) (trans-DDP). In search of the mechanism of action of such compounds, a comparative study on the nucleobase chemistry of trans-DDP and trans-[PtCl(2)(NH(3))(quinoline)] (trans-QUIN) was performed using 1D and 2D NMR spectroscopy and molecular modeling techniques. The two simple monofunctional adducts trans-[PtCl(9-ethylguanine-N7)(NH(3))L]NO(3) (L = NH(3), 1; L = quinoline, 2) were synthesized by employing the AgNO(3)/DMF method. Reactions of these species with 5'-guanosine monophosphate (5'-GMP) and 5'-cytidine monophosphate (5'-CMP) were used to simulate potential second binding steps on DNA. Guanine-N7 proved to be the kinetically preferred binding site for both 1 and 2. Reactions with 2 proceeded significantly slower than those with 1 under the same conditions. These differences in reactivity are attributed to an altered hydrolytic behavior of 2 due to steric influences of quinoline upon associative substitution reactions. This is supported by interligand NOEs observed in the 2D NOESY spectrum of 2 and by AMBER-based geometries for different conformers of 2. Signal splittings observed in the (1)H NMR spectra of 2 and the bifunctional adducts trans-[Pt(9-EtGua-N7)(5'-GMP-N7)(NH(3))L] (4) andtrans-[Pt(9-EtGua-N7)(2)(NH(3))L](2+) (6) (L = quinoline) indicate hindered rotation about the Pt-N (guanine and quinoline) bonds. Temperature-dependent NMR spectra and molecular mechanics results are in agreement with frozen rotamers in solution at room temperature where unfavorable repulsive interligand interactions result in different head-to-head and head-to-tail orientations of the bases. For the different rotamers of 4, a high barrier of interconversion of 87 kJ mol(-)(1) was estimated from NMR data. The consequences of these kinetic and geometric effects with respect to target DNA are discussed.
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Affiliation(s)
- Ulrich Bierbach
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006
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Pérez C, Leng M, Malinge JM. Rearrangement of interstrand cross-links into intrastrand cross-links in cis-diamminedichloroplatinum(II)-modified DNA. Nucleic Acids Res 1997; 25:896-903. [PMID: 9016644 PMCID: PMC146515 DOI: 10.1093/nar/25.4.896] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In the reaction of the anticancer drug cis-diamminedichloroplatinum(II) (cis-DDP) with DNA, bifunctional intrastrand and interstrand cross-links are formed. In this work, we show that at 37 degrees C interstrand cross-links (ICL) are labile and rearrange into intrastrand cross-links. The ICL instability was first studied with a 10 base pairs (bp) double-stranded oligonucleotide containing a unique site-specific ICL resulting from chelation of the N7 position of two guanine residues on the opposite strands of DNA at the d(GC/GC) site by a cis-diammineplatinum(II) residue. The bonds between the platinum and the N7 of guanine residues within the interstrand adduct are cleaved. In 50 mM NaCl or NaClO4, this cleavage results in the formation of monofunctional adducts which subsequently form intrastrand cross-links. One cleavage reaction takes place per cross-linked duplex in either of both DNA strands. Whereas the starting cross-linked 10 bp duplex is hydrogen bonded, the two complementary DNA strands separate after the cleavage of the ICL. Under these conditions, the cleavage reaction is irreversible allowing its rate measurement (t1/2= 29+/-2 h) and closure of monofunctional adducts to intrastrand cross-links occurs within single-stranded DNA. Within a longer cross-linked oligonucleotide (20 bp), ICL are apparently more stable (t1/2= 120+/-12 h) as a consequense of monofunctional adducts closure back to ICL. We propose that the ICL cleavage is reversible in DNA and that these adducts rearrange finally into intrastrand cross-links. Our results could explain an 'ICL unhooking' in previously reported in vivo repair studies [Zhenet al. (1993)Carcinogenesis14, 919-924].
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Affiliation(s)
- C Pérez
- Centre de Biophysique Moléculaire, CNRS, Orléans, France
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Reeder F, Gonnet F, Kozelka J, Chottard JC. Reactions of the Double-Stranded Oligonucleotide d(TTGGCCAA)2 withcis-[Pt(NH3)2(H2O)2]2+ and [Pt(NH3)3(H2O)]2+. Chemistry 1996. [DOI: 10.1002/chem.19960020906] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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