Telomerase recruitment by the telomere end binding protein-β facilitates G-quadruplex DNA unfolding in ciliates
Telomerase recruitment by the telomere end binding protein-β facilitates G-quadruplex DNA unfolding in ciliates
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DOI：
10.1038/nsmb.1422
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发表时间：
2008-06-01
影响因子：
16.8
通讯作者：
Lipps, Hans Joachim
中科院分区：
文献类型：
--
作者：
Paeschke, Katrin;Juranek, Stefan;Lipps, Hans Joachim
纤毛虫柱头的端粒g -悬垂在体内折叠成g -四重DNA结构。端粒g -四重体的形成需要两种端粒末端结合蛋白（TEBP α和TEBP β）的存在，并以细胞周期依赖的方式进行调节。该结构在S期的展开依赖于TEBPb的磷酸化。在这里，我们表明TEBP β磷酸化是必要的，但不是充分的g -四重体展开速率与端粒合成相容。在体内，端粒酶似乎积极参与端粒g -四重体DNA结构的展开。值得注意的是，端粒酶通过磷酸化的TEBP β被募集到端粒，因此端粒酶的募集是通过磷酸化来调节细胞周期的。这些观察结果使我们能够在细胞周期中提出g -四重体展开和端粒合成的调节模型。
The telomeric G-overhangs of the ciliate Stylonychia lemnae fold into a G-quadruplex DNA structure in vivo. Telomeric G-quadruplex formation requires the presence of two telomere end binding proteins, TEBP alpha and TEBP beta, and is regulated in a cell-cycle dependent manner. Unfolding of this structure in S phase is dependent on the phosphorylation of TEBPb. Here we show that TEBP beta phosphorylation is necessary but not sufficient for a G-quadruplex unfolding rate compatible with telomere synthesis. The telomerase seems to be actively involved in telomeric G-quadruplex DNA structure unfolding in vivo. Significantly, the telomerase is recruited to telomeres by phosphorylated TEBP beta, and hence telomerase recruitment is cell-cycle regulated through phosphorylation. These observations allow us to propose a model for the regulation of G-quadruplex unfolding and telomere synthesis during the cell cycle.