Identification of the determinants for the specific recognition of single-strand telomeric DNA by Cdc13
Identification of the determinants for the specific recognition of single-strand telomeric DNA by Cdc13
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DOI：
10.1021/bi0512703
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发表时间：
2006-01-24
期刊：
影响因子：
2.9
通讯作者：
Wuttke, DS
中科院分区：
文献类型：
--
作者：
Eldridge, AM;Halsey, WA;Wuttke, DS
端粒上的单链突出端在介导端粒的加帽和端粒酶调节功能中起着关键作用。端粒末端结合蛋白，Cdc 13在酿酒酵母，Pot 1在高等真核生物，和TEBP在纤毛虫原生动物Oxytricha nova，表现出序列特异性结合到各自的单链突出端。S.酿酒酵母端粒由富含GT的端粒序列的异质混合物组成，这与高等真核生物中具有高保真度维持的简单重复不同。在酵母中，端粒突出端被必需蛋白Cdc 13识别，Cdc 13协调端粒的封端和端粒酶活性。Cdc 13 DNA结合域（Cdc 13-DBD）以高亲和力（3 pM）和序列特异性结合这些端粒序列。为了更好地理解这一显着的识别的基础上，我们已经调查了Cdc 13-DBD的一系列改变的DNA底物的结合。虽然一个1聚体的GT丰富的序列是完全结合亲和力所必需的，只有这11个碱基中的三个被识别具有高特异性。这种特异性不同于在其他已知的端粒末端结合蛋白中观察到的特异性，但非常适合Cdc 13在酵母端粒中的特定作用。这些研究扩展了我们对Cdc 13-DBD端粒识别和ssDNA结合的独特分子识别特性的理解。
The single-strand overhang present at telomeres plays a critical role in mediating both the capping and telomerase regulation functions of telomeres. The telomere end-binding proteins, Cdc13 in Saccharomyces cerevisiae, Pot1 in higher eukaryotes, and TEBP in the ciliated protozoan Oxytricha nova, exhibit sequence-specific binding to their respective single-strand overhangs. S. cerevisiae telomeres are composed of a heterogeneous mixture of GT-rich telomeric sequence, unlike in higher eukaryotes which have a simple repeat that is maintained with high fidelity. In yeast, the telomeric overhang is recognized by the essential protein Cdc13, which coordinates end-capping and telomerase activities at the telomere. The Cdc13 DNA-binding domain (Cdc13-DBD) binds these telomere sequences with high affinity (3 pM) and sequence specificity. To better understand the basis for this remarkable recognition, we have investigated the binding of the Cdc13-DBD to a series of altered DNA substrates. Although an 1-mer of GT-rich sequence is required for full binding affinity, only three of these 11 bases are recognized with high specificity. This specificity differs from that observed in the other known telomere end-binding proteins, but is well suited to the specific role of Cdc13 at yeast telomeres. These studies expand our understanding of telomere recognition by the Cdc13-DBD and of the unique molecular recognition properties of ssDNA binding.