Electron microscopic visualization of telomerase from Euplotes aediculatus bound to a model telomere DNA
Electron microscopic visualization of telomerase from Euplotes aediculatus bound to a model telomere DNA
复制标题
DOI：
10.1021/bi060313s
复制
发表时间：
2006-08-08
期刊：
影响因子：
2.9
通讯作者：
Jarstfer, Michael B.
中科院分区：
文献类型：
--
作者：
Fouche, Nicole;Moon, Ian K.;Jarstfer, Michael B.
纤毛虫端粒酶核糖核蛋白与端粒 DNA 的体外结合已通过电子显微镜 (EM) 进行了检测。所形成的结构的可视化揭示了一种球状蛋白质复合物，该复合物定位于含有 E. aediculatus 端粒共有 3'-单链 T(4)G(4)T(4)G(4)T(4)G(2) 突出端的 DNA 末端。凝胶过滤证实纯化的 E. aediculatus 端粒酶在溶液中是活性二聚体，并且 DNA 相关复合物与脱铁铁蛋白的大小比较表明 E. aediculatus 端粒酶作为二聚体与单个端粒 3' 端结合。电镜显示高达 43% 的端粒酶-DNA 复合物涉及与两个或多个 DNA 末端相关的端粒酶四聚体或更大的多聚体。这些数据提供了端粒酶是功能性二聚体的第一个直接证据，并表明两个端粒酶核糖核蛋白颗粒在体内合作延长每个游标体端粒。
Binding of the telomerase ribonucleoprotein from the ciliate Euplotes aediculatus to telomeric DNA in vitro has been examined by electron microscopy (EM). Visualization of the structures that formed revealed a globular protein complex that localized to the DNA end containing the E. aediculatus telomere consensus 3'-single-strand T(4)G(4)T(4)G(4)T(4)G(2) overhang. Gel filtration confirmed that purified E. aediculatus telomerase is an active dimer in solution, and comparison of the size of the DNA-associated complex with apoferritin suggests that E. aediculatus telomerase binds to a single telomeric 3'-end as a dimer. Up to 43% of the telomerase-DNA complexes appeared by EM to involve tetramers or larger multimers of telomerase in association with two or more DNA ends. These data provide the first direct evidence that telomerase is a functional dimer and suggest that two telomerase ribonucleoprotein particles cooperate to elongate each Euplotes telomere in vivo.