Journal of the American Chemical Society, Vol.120, No.30, 7450-7460, 1998
Characterization of Zn(II)center dot deglycobleomycin A(2) and interaction with d(CGCTAGCG)(2) : Direct evidence for minor groove binding of the bithiazole moiety
Deglycobleomycin (dgBLM) binds to and degrades the self-complementary oligonucleotide d(CGCTAGCG)(2) in a sequence-selective fashion. To characterize the binding interaction, a 1:1 complex of Zn(II). dgBLM A(2) With the DNA octanucleotide has been examined using two-dimensional NMR experiments and restrained molecular dynamics calculations. Critical elements of the mode of DNA interaction within two structural domains of Zn(II). dgBLM Az were fundamentally different than those observed previously for Zn(II). BLM A(2) (Manderville, R. A.; Ellena, J. F.; Hecht, S. M. J. Am. Chem. Sac. 1995, 117, 7891). a miner groove mode of binding by the bithiazole moiety is supported by the present study. Only slight upfield shifting of the bithiazole (Bit) protons Bit H5 and Bit H5' is observed, and the sequential intrastrand NOE connectivities are retained upon Zn(II). dgBLM A(2) binding. The orientation of the drug molecule in the complex is based on the finding of 16 intermolecular Zn(II). dgBLM A(2)-DNA NOEs. The cationic C-substituent of Zn(II). dgBLM A(2) is positioned in the minor groove of the DNA based on the appearance of 10 NOEs between hydrogens located in the minor groove of DNA and the C-substituent of BLM. Additionally, the results are consistent with the interpretation that the DNA octanucleotide cleavage specificity observed from Fe(II). dgBLM A(2) and possibly for Fe(II). BLM A(2) is due in part to recognition of the T-4-A(5) region of the octanucleotide by the bithiazole. Using the NMR-derived NOE distance and dihedral bond angle restraints to guide the molecular dynamics calculations, a binding model for the interaction of Zn(II). dgBLM A(2) With the octanucleotide has been derived.
Keywords:RESTRAINED MOLECULAR-DYNAMICS;MAN-DESIGNED BLEOMYCINS;DNA STRAND SCISSION;DISTANCE GEOMETRY CALCULATIONS;NUCLEAR-MAGNETIC-RESONANCE;CARBON-MONOXIDE COMPLEX;NOE-BASED REFINEMENT;DEOXYRIBONUCLEIC-ACID;SEQUENCE SPECIFICITY;METAL-BINDING