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DNase I footprinting of cis- or trans-diamminedichloroplatinum(II)-modified DNA
1Centre de Biophysique Moléculaire, C.N.R.S., Orléans, France.
Abstract:
DNase I has been used as an enzymatic probe to visualize the conformational alteration induced in DNA by the binding of either the antitumor drug cis-platinum (cis-DDP) or the therapeutically inactive derivatives, trans-platinum (trans-DDP) and chlorodiethylene-triamineplatinum(II) (dien-Pt). We have constructed double-stranded oligonucleotides (52-mer) containing a single adduct either at the d(GG) site (cis-DDP intrastrand cross-link) or at the d(GC/GC) site (cis-DDP interstrand cross-link) or at the d(G/C) site (trans-DDP interstrand cross-link) or at the d(G) site (dien-Pt adduct). The platinated oligonucleotides are differently recognized by DNase I. As judged by DNase I, the distortions induced in the DNA double helix by the cis-DDP and trans-DDP interstrand cross-links spread over more base-pairs than that induced by the cis-DDP intrastrand cross-link.
Insights
DNase I enzyme probes DNA distortions caused by platinum drugs. Interstrand cross-links from cis-platinum (cis-DDP) and trans-platinum (trans-DDP) cause larger DNA helix alterations than cis-DDP intrastrand cross-links.
Area of Science:
- Biochemistry
- Molecular Biology
- Medicinal Chemistry
Background:
- Platinum-based drugs are crucial in cancer chemotherapy.
- Understanding drug-DNA interactions is key to developing new therapies.
- DNase I is a valuable tool for studying DNA conformation changes.
Purpose of the Study:
- To investigate how different platinum drug adducts alter DNA structure.
- To compare the DNA conformational changes induced by cis-platinum (cis-DDP), trans-platinum (trans-DDP), and chlorodiethylene-triamineplatinum(II) (dien-Pt).
- To utilize DNase I as an enzymatic probe to visualize these alterations.
Main Methods:
- Synthesis of 52-mer double-stranded oligonucleotides with specific platinum adducts.
- Adducts included cis-DDP intrastrand cross-link, cis-DDP interstrand cross-link, trans-DDP interstrand cross-link, and dien-Pt adduct.
- Enzymatic digestion of platinated oligonucleotides using DNase I.
- Analysis of DNase I cleavage patterns to infer DNA conformational changes.
Main Results:
- DNase I recognition patterns varied significantly among different platinum adducts.
- Interstrand cross-links induced by cis-DDP and trans-DDP caused more extensive DNA helix distortions.
- The distortions from interstrand cross-links spanned more base pairs compared to the cis-DDP intrastrand cross-link.
Conclusions:
- DNase I effectively distinguishes between DNA conformational alterations induced by various platinum adducts.
- The type and location of platinum-DNA cross-links significantly influence the extent of DNA helix distortion.
- These findings contribute to understanding the structural basis of platinum drug activity and resistance.