A physical and functional constituent of telomerase anchor site
A physical and functional constituent of telomerase anchor site
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DOI：
10.1074/jbc.m503028200
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发表时间：
2005-07-15
影响因子：
4.8
通讯作者：
Lue, NF
中科院分区：
文献类型：
--
作者：
Lue, NF
端粒酶是一种核糖核蛋白逆转录酶，负责维持端粒末端重复序列的一条链。它最低限度地由催化蛋白组分（TERT）和提供模板的RNA亚基组成。与原型逆转录酶相比，端粒酶的独特之处在于具有不同于催化位点的DNA结合结构域（锚位点）。发现在N-末端结构域（称为N-GQ）中具有缺失或点突变的酵母TERT突变体在与端粒酶RNA形成短杂交体的延伸引物中选择性受损。突变体也遭受了显着的损失，重复添加持续合成能力，但显示核苷酸添加持续合成能力的增强。此外，突变体表现出改变的引物利用特性的寡核苷酸含有非端粒残基的5 '-区域。交联研究表明，在端粒聚合酶-端粒复合物的情况下，N-GQ结构域与DNA底物的5 '-区域物理接触。总之，这些结果暗示了作为端粒酶锚位点的物理和功能成分的TERT的N-GQ结构域。再加上以前的遗传分析，我们的数据证实，锚网站的相互作用确实是重要的端粒酶在体内的功能。
Telomerase is a ribonucleoprotein reverse transcriptase responsible for the maintenance of one strand of the telomere terminal repeats. It consists minimally of a catalytic protein component (TERT) and an RNA subunit that provides the template. Compared with prototypical reverse transcriptases, telomerase is unique in possessing a DNA binding domain (anchor site) that is distinct from the catalytic site. Yeast TERT mutants bearing deletion or point mutations in an N-terminal domain (known as N-GQ) were found to be selectively impaired in extending primers that form short hybrids with telomerase RNA. The mutants also suffered a significant loss of repeat addition processivity but displayed an enhancement in nucleotide addition processivity. Furthermore, the mutants manifested altered primer utilization properties for oligonucleotides containing non-telomeric residues in the 5'-region. Crosslinking studies indicate that the N-GQ domain physically contacts the 5'-region of the DNA substrate in the context of a telomerase-telomere complex. Together, these results implicate the N-GQ domain of TERT as a physical and functional constituent of the telomerase anchor site. Coupled with previous genetic analysis, our data confirm that anchor site interaction is indeed important for telomerase function in vivo.