Structure of hnRNP D complexed with single-stranded telomere DNA and unfolding of the quadruplex by heterogeneous nuclear ribonucleoprotein D
Structure of hnRNP D complexed with single-stranded telomere DNA and unfolding of the quadruplex by heterogeneous nuclear ribonucleoprotein D
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DOI：
10.1074/jbc.m411822200
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发表时间：
2005-05-13
影响因子：
4.8
通讯作者：
Katahira, M
中科院分区：
文献类型：
--
作者：
Enokizono, Y;Konishi, Y;Katahira, M
异质核核糖核蛋白D，也称为AUF 1，具有两个DNA/RNA结合结构域，每个结构域都可以特异性结合单链d（TTAGGG）（n），即人类端粒重复序列。在这里，提出的结构的C-末端结合结构域（BD 2）与单链d（TTAGGG）确定的NMR。该结构揭示了d（TAG）片段的每个残基以碱基特异性方式被BD 2识别。从结构推断的相互作用已被证实的凝胶阻滞实验与突变体BD 2和DNA。已知具有端粒重复序列的单链DNA倾向于形成四链体，并且四链体对端粒酶引起的端粒延长具有抑制作用。这一次揭示了BD 2在结合时展开这种DNA的四链体。此外，在体外检测BD 2对端粒酶延长的影响。这些结果表明，异质核核糖核蛋白D可能参与端粒3 '-突出端的维持，通过保护单链DNA或通过端粒酶延长潜在有害的四链体结构的不稳定。
Heterogeneous nuclear ribonucleoprotein D, also known as AUF1, has two DNA/RNA-binding domains, each of which can specifically bind to single-stranded d(TTAGGG)(n), the human telomeric repeat. Here, the structure of the C-terminal-binding domain (BD2) complexed with single-stranded d(TTAGGG) determined by NMR is presented. The structure has revealed that each residue of the d(TAG) segment is recognized by BD2 in a base-specific manner. The interactions deduced from the structure have been confirmed by gel retardation experiments with mutant BD2 and DNA. It is known that single-stranded DNA with the telomeric repeat tends to form a quadruplex and that the quadruplex has an inhibitory effect on telomere elongation by telomerase. This time it is revealed that BD2 unfolds the quadruplex of such DNA upon binding. Moreover, the effect of BD2 on the elongation by telomerase was examined in vitro. These results suggest the possible involvement of heterogeneous nuclear ribonucleoprotein D in maintenance of the telomere 3'-overhang either through protection of a single-stranded DNA or destabilization of the potentially deleterious quadruplex structure for the elongation by telomerase.