端粒酶全酶中与RPA相关的序列特异性DNA结合亚基是延伸持续性和端粒维持所必需的。
An RPA-related sequence-specific DNA-binding subunit of telomerase holoenzyme is required for elongation processivity and telomere maintenance.
作者信息
Min Bosun, Collins Kathleen
机构信息
University of California, Berkeley, 94720-3200, USA.
出版信息
Mol Cell. 2009 Nov 25;36(4):609-19. doi: 10.1016/j.molcel.2009.09.041.
Telomerase ribonucleoprotein complexes copy an internal RNA template to synthesize DNA repeats. DNA-interacting subunits other than telomerase reverse transcriptase (TERT) and telomerase RNA (TER) have been hypothesized to account for high repeat addition processivity of telomerase holoenzyme compared to the minimal catalytic RNP. Here, we present the identification of three additional subunits of Tetrahymena thermophila telomerase holoenzyme. Each of seven telomerase proteins is required for telomere maintenance and copurifies active RNP. The catalytic core (p65-TER-TERT) is assembled with a three-protein subcomplex (p75-p45-p19) and two peripheral subunits (p82 and p50). Remarkably, only a p82-enriched subset of the total holoenzyme population is capable of high repeat addition processivity, as shown by p82 immunodepletion and add-back. The RPA-like p82 subunit binds sequence specifically to multiple telomeric repeats. These discoveries establish the existence of a telomerase holoenzyme processivity subunit with sequence-specific DNA binding.
端粒酶核糖核蛋白复合物通过复制内部RNA模板来合成DNA重复序列。除了端粒酶逆转录酶（TERT）和端粒酶RNA（TER）之外，与DNA相互作用的亚基被认为可以解释端粒酶全酶相较于最小催化性核糖核蛋白具有更高的重复序列添加持续性。在此，我们展示了嗜热四膜虫端粒酶全酶另外三个亚基的鉴定。七种端粒酶蛋白中的每一种对于端粒维持都是必需的，并且能与活性核糖核蛋白共纯化。催化核心（p65-TER-TERT）与一个由三种蛋白组成的亚复合物（p75-p45-p19）以及两个外周亚基（p82和p50）组装在一起。值得注意的是，如p82免疫去除和回补实验所示，全酶群体中只有富含p82的亚群具有高重复序列添加持续性。类RPA的p82亚基能特异性结合多个端粒重复序列。这些发现证实了存在一种具有序列特异性DNA结合能力的端粒酶全酶持续性亚基。
Zotero 插件