2D NMR investigation of the binding of the anticancer drug actinomycin D to duplexed dATGCGCAT: conformational features of the unique 2:1 adduct.
2D NMR investigation of the binding of the anticancer drug actinomycin D to duplexed dATGCGCAT: conformational features of the unique 2:1 adduct.
复制标题
抗癌药物放线菌素 D 与双链 dATGCGCAT 结合的 2D NMR 研究：独特 2:1 加合物的构象特征。
DOI：
10.1021/bi00420a053
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Wilson,WD
中科院分区：
文献类型：
--
作者：
Scott,EV;Zon,G;Marzilli,LG;Wilson,WD
Department of Chemistry, Emory University, Atlanta, Georgia 30322, Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, and Applied Biosystems, Foster City, California 94404 Received April 22, 1988; Revised Manuscript Received June 6, 1988 abstract: One-and two-dimensional NMR studies on the oligomer dA1T2G3C4G5C6A7T8, with and without actinomycin D (ActD), were conducted. Analysis of the NMR data, particularly 2D NOE intensities, revealed that the free oligonucleotide is a duplex in a standard right-handed B form. At the ratio of 1 ActD/duplex (R= 1), ID NMR studies indicatethat two 1: 1 unsymmetric complexes form in unequal proportions with the phenoxazone ring intercalated at a GpC site, in agreement with previous studies [Scott, E. V., Jones, R. L., Banville, DL, Zon, G., Marzilli, L. G., & Wilson, WD (1988) Biochemistry 27, 915-923], The 2D COSY data also confirm this interpretation since eight cytosine H6 to H5 andtwo ActD H8 to H7 cross-peaks are observed. At R= 2, both COSY and NOESY spectra confirm the formation of a unique 2: 1 species with C2 symmetry. The oligomer remains in a right-handed duplex but undergoes extreme conformational changes both at and adjacent to the binding site. The deoxyribose conformation of T2, C4, and C6 shifts from primarily C2/-endo in the free duplex to an increased amount of C3'-endo in the 2: 1 complex as revealed by the greater intensity of the base H6 to 3'NOE cross-peak relative to the intensity of the H6 to H2'NOE cross-peak. Thisconformational change widens the minor groove and should help alleviate the steric crowding of the ActD peptides. The orientation of the ActD molecules at R= 2 has the quinoid portion of the phenoxazone ring at the G3pC4 site and the benzenoid portion of the phenoxazone ring at the G5pC6 site on the basis of NOE cross-peaks from ActD H7 and H8 to G5H8 and C6H6. All base pairs retain Watson-Crick type H-bonding, unlike echinomycin complexes [eg, Gao, X., & Patel, D. J.(1988) Biochemistry 27, 1744-1751] where Hoogsteen base pairs have been observed. In contrast to previous studies on ActD, we were able to distinguish the two peptide chains. From NOE’s between the threonine ß protons and GH1'protons, as well as other evidence, it was clear that the cyclic peptide rings of ActD bind inthe minor groove of the DNA with the peptide ring on the quinoid side of the phenoxazone ring pointing towardthe end of the duplex and the benzenoid peptide pointing into the center of the duplex. The amino acid protons in the quinoid ring and benzenoid ring have significantly different chemicalshifts. However, only the signals of the cyclic peptide pointing toward the center of the duplex and hence toward its equivalent peptide on the other, C2 related, ActD molecule had unusual shifts. Since these chains are in a crowded region, as evidenced by examination of models, they evidently have undergone a conformational change. The peptide interactions in this close-packed region may be responsible for the unique 2: 1 species, for the negative cooperativity in binding, and for the conformational changes in the deoxyribose moieties. e anticancer agent actinomycin D (ActD), 1 because of its unique structure (Chart I) and DNA binding properties, has been beneficial in the understanding of base pair specific interactions (Muller & Crothers, 1968; Sobell, 1973; Dervan, 1986; Waring, 1981). ActD displays unusually high specificity for binding to GC sequences (Jain & Sobell, 1972; Sobell & Jain, 1972; Sobell, 1980; Wells & Larson, 1970; Chen, 1988), displays cooperative binding to some DNA sequences, and appears to induce long-range …
