TRF1 promotes parallel pairing of telomeric tracts in vitro
TRF1 promotes parallel pairing of telomeric tracts in vitro
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DOI：
10.1006/jmbi.1998.1686
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发表时间：
1998-04-24
影响因子：
5.6
通讯作者：
de Lange, T
中科院分区：
文献类型：
--
作者：
Griffith, J;Bianchi, A;de Lange, T
人类端粒由长串的TTAGGG重复序列组成，这些重复序列与端粒特异性蛋白质TRF1和TRF2结合。在此我们描述通过电子显微镜推断出的端粒DNA和TRF1之间在体外形成的复合物结构。对结合到含有6个或12个串联TTAGGG重复序列的DNA上的TRF1进行可视化观察，发现一群DNA含有一个恰好定位在重复序列上的球形蛋白质复合物。对蛋白质复合物的质量分析表明TRF1二聚体和四聚体与TTAGGG重复序列结合。蛋白质结合并没有使DNA显著压缩或伸展。TRF1在较长的端粒重复序列阵列（≥27个重复序列）上形成丝状结构，这与一系列结合的TRF1二聚体的存在是一致的。出乎意料的是，两个端粒片段在被TRF1覆盖的区域上有很强的形成配对突触的倾向。多达30%的与TRF1结合的DNA可以以配对形式被发现，并且与反平行排列相比，强烈倾向于平行排列。使用连接试验证实了TRF1诱导的配对，该试验检测到依赖于TRF1存在以及DNA中27聚体重复序列阵列的DNA多聚体的形成。这些发现表明这种蛋白质可能在端粒中具有一种结构作用。我们讨论了端粒构象的TRF1依赖性变化参与端粒长度调节的可能性。（C）1998年学术出版社有限公司。
Human telomeres consist of long arrays of TTAGGG repeats bound to the telomere-specific proteins, TRF1 and TRF2. Here we describe the structure of in vitro complexes formed between telomeric DNA and TRF1 as deduced by electron microscopy. Visualization of TRF1 bound to DNA containing six or 12 tandem TTAGGG repeats revealed a population of DNAs containing a spherical protein complex localized just to the repeats. Mass analysis of the protein complexes suggested binding of TRF1 dimers and tetramers to the TTAGGG repeats. The DNA was not significantly compacted or extended by protein binding. TRF1 formed filamentous structures on longer telomeric repeat arrays (greater than or equal to 27 repeats) consistent with the presence of an array of bound TRF1 dimers. Unexpectedly, there was a strong propensity for two telomeric tracts to form paired synapses over the TRF1 covered segment. Up to 30% of the TRF1-bound DNAs could be found in a paired configuration with a strong bias for a parallel as contrasted to an antiparallel arrangement. TRF1-induced pairing was confirmed using a ligation assay which detected the formation of DNA multimers dependent on the presence of TRF1 and a 27mer repeat array in the DNA. These findings suggests that this protein may have an architectural role at telomeres. We discuss the possibility that TRF1-dependent changes in the conformation of telomeres are involved in the regulation of telomere length. (C) 1998 Academic Press Limited.