UTILIZATION OF RIBONUCLEOTIDES AND RNA PRIMERS BY TETRAHYMENA TELOMERASE
UTILIZATION OF RIBONUCLEOTIDES AND RNA PRIMERS BY TETRAHYMENA TELOMERASE
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DOI：
10.1002/j.1460-2075.1995.tb00226.x
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发表时间：
1995-11-01
期刊：
影响因子：
11.4
通讯作者：
GREIDER, CW
中科院分区：
文献类型：
--
作者：
COLLINS, K;GREIDER, CW
端粒酶是参与端粒合成的核糖核蛋白（RNP）DNA聚合酶，端粒酶RNA组分内的短序列提供了将端粒简单重复序列的富含G的链从头添加到染色体末端上的模板。一个引物可以在产物解离之前通过多轮模板复制延伸，端粒酶将掺入dNTP或ddNTP并将延长任何富含G的单链引物DNA，在这篇报道中，我们发现四膜虫端粒酶能够将核糖核苷酸rGTP掺入产物多核苷酸中，产物[d（TT）r（GGGG）]（n）的合成是进行性的，这表明嵌合产物在活性位点和第二个先前表征的不依赖模板的产物结合位点都与酶结合。引物3'端的RNA长度超过3nt时，产物合成量减少，但引物对端粒酶的亲和力增加。因此，含RNA的引物是有效的竞争性抑制剂的DNA引物延伸的端粒酶，这些结果支持可能的进化起源的端粒酶作为一种RNA依赖的RNA聚合酶。
Telomerase is a ribonucleoprotein (RNP) DNA polymerase involved in telomere synthesis, A short sequence within the telomerase RNA component provides a template for de novo addition of the G-rich strand of a telomeric simple sequence repeat onto chromosome termini, In vitro, telomerase can elongate single-stranded DNA primers processively: one primer can be extended by multiple rounds of template copying before product dissociation, Telomerase will incorporate dNTPs or ddNTPs and will elongate any G-rich, single-stranded primer DNA, In this report, we show that Tetrahymena telomerase was able to incorporate a ribonucleotide, rGTP, into product polynucleotide, Synthesis of the product [d(TT)r(GGGG)](n) was processive, suggesting that the chimeric product remained associated with the enzyme both at the active site and at a second, previously characterized, template-independent product binding site, As predicted by this finding, RNA-containing oligonucleotides served as primers for elongation, More than 3 nt of RNA at a primer 3' end decreased the quantity of product synthesis but increased the affinity of the primer for telomerase. Thus, RNA-containing primers were effective as competitive inhibitors of DNA primer elongation by telomerase, These results support the possible evolutionary origin of telomerase as an RNA-dependent RNA polymerase.