Interactions of Deglycosylated Cobalt(III)-Pepleomycin (Green Form) with DNA Based on NMR Structural Studies

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• 作者：Janet Caceres-Cortes ; Hiroshi Sugiyama ; Kenji Ikudome ; Isao Saito ; and Andrew H.-J. Wang
• 刊名：Biochemistry
• 出版年：1997
• 出版时间：August 19, 1997
• 年：1997
• 卷：36
• 期：33
• 页码：9995 - 10005
• 全文大小：246K
• 年卷期：v.36,no.33(August 19, 1997)
• ISSN：1520-4995

文摘

Pepleomycin (PEP)¹ is a metalloglycopeptideantitumor antibiotic that has improvedpharmacological properties than does bleomycin (BLM). Both PEP andBLM bind to and degrade DNAin a sequence-selective manner. The binding interactions ofHO₂^--Co(III)-CodPEP (CodPEP)withCGTACG have been studied by 2D NMR and molecular modeling.Inspection of the 2D-NMR datarevealed 60 notable intermolecular NOEs between CodPEP and CGTACG whichplace the drug's metalbinding domain and peptide linker in the minor groove of the DNA closeto G8 and T9. On the basis ofthe NOEs, the drug's DNA binding domain is located close to theT9·A4 and A10·T3 base pairs.Intercalation of the bithiazole tail between these base pairs isindicated by the loss of DNA symmetryupon complexation with CodPEP, by a break in the sequentialconnectivity at the TpA steps, and by theupfield shift of the bithiazole H-H5 and H-H5' proton resonances.Intercalation of the bithiazole moietyunfolds the CodPEP molecule and exposes its hydroperoxide group to theDNA. The hydroperoxidegroup in the refined model of CodPEP-CGTACG is close to the C4'proton of T9, consistent with cleavageat this position. The NOE pattern between the pyrimidine ring ofCodPEP and G8 of DNA suggests aspecific pairing recognition via hydrogen bonds between these groups,thus establishing a 5'-GT-3' sequencepreference. The structural elucidation of the free CodPEP andCoPEP [Caceres-Cortes et al. (1997) Eur.J. Biochem. 244, 818-828], and of the complex ofCodPEP-CGTACG afford a plausible mechanism forthe recognition and its subsequent cleaving of DNA by the drug.The process involves the unfolding ofthe compact CodPEP, recognition of a guanine base using the metalbinding domain, threading of thebithiazole tail between base pairs, and finally positioning of theHO₂^- group close to the T or C found3'to the specific G site.