Sequence-Recognition and Cleavage of DNA by a Netropsin-phenazine-di-N-oxide Conjugate
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- 作者：Philippe Helissey ; Sylviane Giorgi-Renault ; Pierre Colson ; Claude Houssier ; and Christian Bailly
- 刊名：Bioconjugate Chemistry
- 出版年：2000
- 出版时间：March 2000
- 年：2000
- 卷：11
- 期：2
- 页码：219 - 227
- 全文大小：290K
- 年卷期：v.11,no.2(March 2000)
- ISSN：1520-4812
文摘
We report the synthesis, DNA-binding and cleaving properties, and cytotoxic activities of R-128, ahybrid molecule in which a bis-pyrrolecarboxamide-amidine element related to the antibiotic netropsinis covalently tethered to a phenazine-di-N-oxide chromophore. The affinity and mode of interaction ofthe conjugate with DNA were investigated by a combination of absorption spectroscopy, circulardichroism, and electric linear dichroism. This hybrid molecule binds to AT-rich sequences of DNA viaa bimodal process involving minor groove binding of the netropsin moiety and intercalation of thephenazine moiety. The bidentate mode of binding was evidenced by linear dichroism using calf thymusDNA and poly(dA-dT)·(dA-dT). In contrast, the drug fails to bind to poly(dG-dC)·poly(dG-dC), becauseof the obstructive effect of the guanine 2-amino group exposed in the minor groove of this polynucleotide.DNase I footprinting studies indicated that the conjugate interacts preferentially with AT-richsequences, but the cleavage of DNA in the presence of a reducing agent can occur at different sequencesnot restricted to the AT sites. The main cleavage sites were detected with a periodicity of about 10base pairs corresponding to approximately one turn of the double helix. This suggests that the cleavagemay be dictated by the structure of the double helix rather than the primary nucleotide sequence.The conjugate which is moderately toxic to cancer cells complements the tool box of reagents whichcan be utilized to produce DNA strand scission. The DNA cleaving properties of R-128 entreat furtherexploration into the use of phenazine-di-N-oxides as tools for investigating DNA structure.