Crystal structure of the N-terminal domain of Oxytricha nova telomere end-binding protein α subunit both uncomplexed and complexed with telomeric ssDNA
Crystal structure of the N-terminal domain of Oxytricha nova telomere end-binding protein α subunit both uncomplexed and complexed with telomeric ssDNA
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DOI：
10.1006/jmbi.2000.5191
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发表时间：
2001-12-14
影响因子：
5.6
通讯作者：
Schultz, SC
中科院分区：
文献类型：
--
作者：
Classen, S;Ruggles, JA;Schultz, SC
Oxytrichia nova端粒末端结合蛋白特异性识别并封端O.新星大核染色体与OnTEBP α亚基的N-末端结构域同源的蛋白质现已在Oxytricha trifallax、Stylonychia myelia、Euplotes crassus、Schizosophylomycespombe和Homo sapiens中鉴定，表明该蛋白质广泛分布于真核生物中。本文描述了O. nova端粒末端结合蛋白α亚基未复合和与单链端粒DNA复合。这些结构显示了在不存在β亚基和没有α二聚化的情况下，α的N-末端结构域如何单独地以序列特异性和3 '-末端特异性的方式结合单链端粒DNA。此外，这种蛋白质的未复合和复合形式的比较表明，ssDNA结合位点在很大程度上是预先组织的ssDNA与适度的，但有趣的，组成的ssDNA结合位点的氨基酸侧链的重排的情况下。本文所描述的结构扩展了我们对O.通过将未复合和复合形式的单体α加入到先前描述的（α 56/ssDNA）（2）二聚体和α 56/β 28/ssDNA三元复合物的结构中，我们相信，这四个结构中的每一个都代表了O的有序组装/分解途径中的中间体。新星端粒复合物。(C)北京：科学出版社.
Oxytrichia nova telomere end-binding protein specifically recognizes and caps single strand (T(4)G(4))(n) telomeric DNA at the very T-ends of O. nova macronuclear chromosomes. Proteins homologous to the N-terminal domain of OnTEBP alpha subunit have now been identified in Oxytricha trifallax, Stylonychia mytilis, Euplotes crassus, Schizosaccharomyces pombe, and Homo sapiens, suggesting that this protein is widely distributed in eukaryotes. We describe here the crystal structures of the N-terminal single-stranded DNA (ssDNA)-binding domain of O. nova telomere end-binding protein alpha subunit both uncomplexed and complexed with single strand telomeric DNA. These structures show how the N-terminal domain of alpha alone, in the absence of the beta subunit and without alpha dimerization, can bind single-stranded telomeric DNA in a sequence-specific and 3'-end-specific manner. Furthermore, comparison of the uncomplexed and complexed forms of this protein shows that the ssDNA-binding site is largely pre-organized in the absence of ssDNA with modest, but interesting, rearrangements of amino acid side-chains that compose the ssDNA-binding site. The structures described here extend our understanding of structures of O. nova telomeric complexes by adding uncomplexed and complexed forms of monomeric alpha to previously described structures for (alpha56/ssDNA)(2) dimer and alpha56/beta28/ssDNA ternary complexes. We believe that each of these four structures represent intermediates in an ordered assembly/disassembly pathway for O. nova telomeric complexes. (C) 2001 Academic Press.