Autexier C, Greider C W
Cold Spring Harbor Laboratory, New York 11724, USA.
Genes Dev. 1995 Sep 15;9(18):2227-39. doi: 10.1101/gad.9.18.2227.
Telomerase is a DNA polymerase fundamental to the replication and maintenance of telomere sequences at chromosome ends. The RNA component of telomerase is essential for the synthesis of telomere repeats. In vitro, the template domain (5'-CAACCCCAA-3') of the Tetrahymena telomerase RNA dictates the addition of Tetrahymena-specific telomere repeats d(TTGGGG)n, onto the 3' end of G-rich or telomeric substrates that are base-paired with the template and alignment regions of the RNA. Using a reconstituted in vitro system, we determined that altering the sequence of the alignment and template domains affects processivity of telomerase without abolishing telomerase activity. These results suggest that alternative template/alignment regions may be functional. In the ciliate telomerase RNAs, there is a conserved sequence 5'-(CU)GUCA-3', located two residues upstream of the template domain. The location and sequence of this conserved domain defined the 5' boundary of the template region. These data provide insights into the regulation of telomere synthesis by telomerase.
端粒酶是一种DNA聚合酶，对染色体末端端粒序列的复制和维持至关重要。端粒酶的RNA组分对于端粒重复序列的合成必不可少。在体外，嗜热四膜虫端粒酶RNA的模板结构域（5'-CAACCCCAA-3'）决定了嗜热四膜虫特异性端粒重复序列d(TTGGGG)n添加到与RNA的模板和比对区域碱基配对的富含G或端粒底物的3'末端。使用重组体外系统，我们确定改变比对和模板结构域的序列会影响端粒酶的持续合成能力，但不会消除端粒酶活性。这些结果表明，替代的模板/比对区域可能具有功能。在纤毛虫端粒酶RNA中，在模板结构域上游两个残基处有一个保守序列5'-(CU)GUCA-3'。这个保守结构域的位置和序列定义了模板区域的5'边界。这些数据为端粒酶对端粒合成的调控提供了见解。
