CRYSTAL-LATTICE PACKING IS IMPORTANT IN DETERMINING THE BEND OF A DNA DODECAMER CONTAINING AN ADENINE TRACT
CRYSTAL-LATTICE PACKING IS IMPORTANT IN DETERMINING THE BEND OF A DNA DODECAMER CONTAINING AN ADENINE TRACT
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DOI：
10.1073/pnas.86.6.1816
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发表时间：
1989-03-01
影响因子：
11.1
通讯作者：
STEITZ, TA
中科院分区：
文献类型：
--
作者：
DIGABRIELE, AD;SANDERSON, MR;STEITZ, TA
DNA双链十二聚体d（CGCAAAAATGCG）及其互补链的晶体结构已在2.6埃下测定。分辨率虽然我们的目标是推导出溶液中腺嘌呤束结构所表现出的螺旋轴静态弯曲的结构特征，但我们得出结论，20 °的整体弯曲。在这里观察到的主要沟槽的方向上的力来自于与晶体堆积相关的力。在一条链上溴化的同晶十二聚体提供了实验证据，证明这种不对称序列在晶格中以180 °相关的两个取向定位。围绕序列的伪二轴旋转。这两个不同位置的DNA分子的弯曲取决于它们在晶体中的取向，而不是它们的序列。与先前确定的含有腺嘌呤束的结构一样，腺嘌呤和胸腺嘧啶碱基对是高度螺旋桨扭曲的。腺嘌呤的N-6与胸腺嘧啶的O-4的氢键距离在螺旋下一步，促进腺嘌呤束内形成一系列分叉氢键。腺嘌呤束相对较直，弯曲位于此区域之外。
The crystal structure of a DNA duplex dodecamer d(CGCAAAAATGCG) and its complementary strand has been determined at 2.6-.ANG. resolution. Although our goal was to deduce the structural features of the static bending of the helical axis exhibited by adenine-tract structures in solution, we conclude that the overall bend of 20.degree. in the direction of the major groove observed here arises from the forces associated with crystal packing. An isomorphous dodecamer brominated on one strand provides experimental evidence that this asymmetric sequences is positioned in two orientations in the crystal lattice that are related by a 180.degree. rotation around the pseudodyad axis of the sequence. The bend in these two differently positioned DNA molecules depends on their orientation in the crystal, not on their sequence. As with previously determined structures containing adenine tracts, the adenine and thymine base pairs are highly propeller twisted. The N-6 of the adenine comes with hydrogen bonding distance of the O-4 of thymine one step down the helix, facilitating the formation of a series of bifurcated hydrogen bonds within the adenine tract. The adenine tract is relatively straight and the bending is localized outside this region.