DNA-induced dimerization of the single-stranded DNA binding telomeric protein Pot1 from Schizosaccharomyces pombe.
DNA-induced dimerization of the single-stranded DNA binding telomeric protein Pot1 from Schizosaccharomyces pombe.
复制标题
DOI：
10.1093/nar/gkr721
复制
发表时间：
2012-01
影响因子：
14.9
通讯作者：
Cech TR
中科院分区：
文献类型：
--
作者：
Nandakumar J;Cech TR
真核染色体末端被称为端粒的蛋白质-DNA复合物保护，不受非法DNA连接的影响。在大多数研究的生物体中，端粒DNA由多个短的富含G的重复序列组成，这些重复序列以受蛋白质POT 1保护的单链尾部结束。哺乳动物POT 1以序列特异性方式结合两个端粒重复序列作为单体，并区分端粒序列的RNA。在解决SpPot 1，POT 1同源物裂殖酵母的RNA歧视特性，我们发现了一个意想不到的ssDNA结合模式，其中两个SpPot 1分子结合含有两个端粒重复的寡核苷酸。DNA结合似乎是通过每个单体的最N-末端OB结构域与每个端粒重复序列的结合来实现的。SpPot 1二聚体可能已经进化以适应S之间发生的异质间隔区。粟酒裂殖酵母端粒重复序列，它也有端粒结构的影响。进一步证明了S.粟酒裂殖酵母端粒蛋白Tpz 1，像它的哺乳动物同源物TPP 1，增加了Pot 1对端粒单链DNA的亲和力，并增强了Pot 1对RNA的辨别力。
Eukaryotic chromosome ends are protected from illicit DNA joining by protein–DNA complexes called telomeres. In most studied organisms, telomeric DNA is composed of multiple short G-rich repeats that end in a single-stranded tail that is protected by the protein POT1. Mammalian POT1 binds two telomeric repeats as a monomer in a sequence-specific manner, and discriminates against RNA of telomeric sequence. While addressing the RNA discrimination properties of SpPot1, the POT1 homolog in Schizosaccharomyces pombe, we found an unanticipated ssDNA-binding mode in which two SpPot1 molecules bind an oligonucleotide containing two telomeric repeats. DNA binding seems to be achieved via binding of the most N-terminal OB domain of each monomer to each telomeric repeat. The SpPot1 dimer may have evolved to accommodate the heterogeneous spacers that occur between S. pombe telomeric repeats, and it also has implications for telomere architecture. We further show that the S. pombe telomeric protein Tpz1, like its mammalian homolog TPP1, increases the affinity of Pot1 for telomeric single-stranded DNA and enhances the discrimination of Pot1 against RNA.