Pilch D S, Dunham S U, Jamieson E R, Lippard S J, Breslauer K J
Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ, 08854-5635, USA.
J Mol Biol. 2000 Feb 25;296(3):803-12. doi: 10.1006/jmbi.2000.3496.
The anticancer activity of cisplatin derives from its ability to bind and cross-link DNA, with the major adduct being the 1,2-d(GpG) intrastrand cross-link. Here, the consequences of this adduct on the conformation, thermal stability, and energetics of duplex DNA are assessed, and the modulation of these parameters by the sequence context of the adduct is evaluated. The properties of a family of 15-mer DNA duplexes containing a single 1,2-d(GpG) cis-¿Pt(NH(3))(2)¿(2+) intrastrand cross-link are probed in different sequence contexts where the flanking base-pairs are systematically varied from T.A to C.G to A.T. By using a combination of spectroscopic and calorimetric techniques, the structural, thermal, and thermodynamic properties of each duplex, both with and without the cross-link, are characterized. Circular dichroism spectroscopic data reveal that the cross-link alters the structure of the host duplex in a manner consistent with a shift from a B-like to an A-like conformation. Thermal denaturation data reveal that the cross-link induces substantial thermal and thermodynamic destabilization of the host duplex. Significantly, the magnitudes of these cross-link-induced effects on duplex structure, thermal stability, and energetics are influenced by the bases that flank the adduct. The presence of flanking A.T base-pairs, relative to T.A or C.G base-pairs, enhances the extent of cross-link-induced alteration to an A-like conformation and dampens the extent of cross-link-induced duplex destabilization. These results are discussed in terms of available structural data, and in terms of the selective recognition of cisplatin-DNA adducts by HMG-domain proteins.
顺铂的抗癌活性源于其与DNA结合并形成交联的能力，主要加合物为1,2 - d(GpG)链内交联。在此，评估了这种加合物对双链DNA构象、热稳定性和能量学的影响，并评估了加合物序列背景对这些参数的调节作用。在不同的序列背景下探测了一族含有单个1,2 - d(GpG)顺式 - [Pt(NH₃)₂]²⁺链内交联的15聚体DNA双链体的性质，其中侧翼碱基对从T.A系统地变化为C.G再到A.T。通过结合光谱和量热技术，对每个双链体在有和没有交联情况下的结构、热和热力学性质进行了表征。圆二色光谱数据表明，交联以一种与从B型构象向A型构象转变相一致的方式改变了宿主双链体的结构。热变性数据表明，交联诱导了宿主双链体显著的热和热力学不稳定。值得注意的是，这些交联诱导的对双链体结构、热稳定性和能量学的影响程度受加合物侧翼碱基的影响。相对于T.A或C.G碱基对，侧翼A.T碱基对的存在增强了交联诱导向A型构象转变的程度，并减弱了交联诱导的双链体不稳定程度。根据现有的结构数据以及HMG结构域蛋白对顺铂 - DNA加合物的选择性识别对这些结果进行了讨论。
