The structure of an RNA/DNA hybrid: A substrate of the ribonuclease activity of HIV-1 reverse transcriptase
The structure of an RNA/DNA hybrid: A substrate of the ribonuclease activity of HIV-1 reverse transcriptase
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DOI：
10.1006/jmbi.1996.0658
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发表时间：
1996-12-06
影响因子：
5.6
通讯作者：
Finzel, BC
中科院分区：
文献类型：
--
作者：
Horton, NC;Finzel, BC
RNA和DNA的互补杂交双链体的结构已经通过X射线晶体学确定。将序列为5 ′-G-G-C-G-C-C-C-G-A-A-3 ′的10个残基的DNA寡核苷酸与互补RNA（5 ′-u-u-c-g-g-g-cg-cc-3 ′）退火并结晶，产生四聚体晶体，其结晶至2.3埃分辨率。混合物采用的几何形状，既不是严格的A型也不是B型，而螺旋具有两者的品质，让人想起光谱描述的混合构象，或II型。所有的核糖核苷酸都保持A型中所见的C3 '-内构象，而在脱氧核糖核苷酸中发现C3'-内构象和C2 '-内构象。小沟宽度（8.5至10.5埃）介于A型（11埃）和B型（7.4埃）DNA的标准值之间。整体参数上升和碱基对倾斜（或倾斜）类似于A-DNA，但滑动和x位移（Dr）更类似于A-RNA，从而赋予杂交体独特的构象。此外，10-mer结晶的方式，允许形成二聚体，堆叠端到端，从而提供了一个扩展的（20碱基对）的RNA-DNA杂交体的螺旋可能出现的一瞥。这个双链体序列被选择用于研究，因为它是由HIV逆转录酶的核糖核酸酶H功能特异性识别。这种酶的底物的结构在理解这一重要药物靶标的选择性要求方面具有潜在价值。与核糖环的2-OH对齐的杂交双链体的小沟是RNA/DNA杂交体的唯一区别特征，无疑是赋予选择性的重要结构特征。(C)1996年学术出版社
The structure of a complementary hybrid duplex of RNA and DNA has been determined by X-ray crystallography. A ten residue DNA oligonucleotide of sequence 5'-G-G-C-G-C-C-C-G-A-A-3' was annealed to complementary RNA (5'-u-u-c-g-g-g-cg-cc-3') and crystallized, producing tetragonal crystals that diffract to 2.3 Angstrom resolution. The hybrid adopts a geometry that is neither strictly A nor B-form rather the helix possesses qualities of both, reminiscent of spectroscopic descriptions of a hybrid conformation, or II-form. All of the ribonucleotides maintain the C3'-endo conformation seen in A-form, while both C3'-endo and C2'-endo conformations are found in the deoxyribonucleotides. The minor groove width (8.5 to 10.5 Angstrom) is intermediate between standard values for A (11 Angstrom) and B-form (7.4 Angstrom) DNA. The global parameters rise and base-pairs tilt (or inclination) are Like that of A-DNA, however the slide and x displacement (Dr) are more like that of A-RNA, thus giving the hybrid a unique conformation. In addition, the 10-mer crystallizes in a manner that allows the formation of dimers that stack end-to-end, thereby providing a glimpse of how an extended (20 base-pair) helix of RNA-DNA hybrid might appear.This duplex sequence was selected for study because it is specifically recognized by the ribonuclease H function of HIV reverse transcriptase. A structure of a substrate of this enzyme is of potential value in understanding requirements for the selectivity of this important drug target. The minor groove of the hybrid duplex, lined with the 2-OH of the ribose rings, is the single distinguishing characteristic of the RNA/DNA hybrid, undoubtedly an important structural feature conferring selectivity. (C) 1996 Academic Press Limited