Two RNA subunits and POT1a are components of Arabidopsis telomerase (Retracted Article)
Two RNA subunits and POT1a are components of Arabidopsis telomerase (Retracted Article)
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DOI：
10.1073/pnas.1013021107
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发表时间：
2011-01-04
影响因子：
11.1
通讯作者：
Shippen, Dorothy E.
中科院分区：
文献类型：
--
作者：
Cifuentes-Rojas, Catherine;Kannan, Kalpana;Shippen, Dorothy E.
端粒酶是一种核糖核蛋白（RNP）逆转录酶，其必需RNA亚基（TER）是端粒重复合成的模板。本文报道了开花植物拟南芥中两个不同的TER片段的鉴定。虽然TER1和TER2在体外都能与端粒酶活性共同作用，并作为端粒酶的模板，但在体内，TER1而不是TER2的缺失会导致端粒酶活性下降和端粒逐渐缩短。此外，TER1中模板结构域的突变导致染色体末端突变端粒重复序列的结合。因此，TER1提供了体内端粒酶的主要模板。我们还发现，POT1a结合TER1的Kd值为2 × 10(-7) M，这两个组分在体内组装成一个酶活性的RNP。相比之下，没有观察到TER1-POT1b和TER2-POT1a的关联。在其他生物体中，POT1蛋白结合端粒DNA并提供染色体末端保护。我们认为，拟南芥中TER和POT1的重复促进了新型蛋白-核酸相互作用的进化，以及POT1从端粒向端粒酶RNP的迁移。
Telomerase is a ribonucleoprotein (RNP) reverse transcriptase whose essential RNA subunit (TER) functions as a template for telomere repeat synthesis. Here we report the identification of two divergent TER moieties in the flowering plant Arabidopsis thaliana. Although both TER1 and TER2 copurify with telomerase activity and serve as templates for telomerase in vitro, depletion of TER1, but not TER2, leads to decreased telomerase activity and progressive telomere shortening in vivo. Moreover, mutation of the templating domain in TER1 results in the incorporation of mutant telomere repeats on chromosome ends. Thus, TER1 provides the major template for telomerase in vivo. We also show that POT1a binds TER1 with a Kd of 2 x 10(-7) M and the two components assemble into an enzymatically active RNP in vivo. In contrast, TER1-POT1b and TER2-POT1a associations were not observed. In other organisms POT1 proteins bind telomeric DNA and provide chromosome end protection. We propose that duplication of TER and POT1 in Arabidopsis fueled the evolution of novel protein-nucleic acid interactions and the migration of POT1 from the telomere to the telomerase RNP.