Taggart Andrew K P, Teng Shu-Chun, Zakian Virginia A
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Science. 2002 Aug 9;297(5583):1023-6. doi: 10.1126/science.1074968.
In Saccharomyces cerevisiae, the telomerase components Est2p, TLC1 RNA, Est1p, and Est3p are thought to form a complex that acts late during chromosome replication (S phase) upon recruitment by Cdc13p, a telomeric DNA binding protein. Consistent with this model, we show that Est1p, Est2p, and Cdc13p are telomere-associated at this time. However, Est2p, but not Est1p, also binds telomeres before late S phase. The cdc13-2 allele has been proposed to be defective in recruitment, yet Est1p and Est2p telomere association persists in cdc13-2 cells. These findings suggest a model in which Est1p binds telomeres late in S phase and interacts with Cdc13p to convert inactive, telomere-bound Est2p to an active form.
在酿酒酵母中，端粒酶组分Est2p、TLC1 RNA、Est1p和Est3p被认为会形成一种复合物，该复合物在染色体复制后期（S期），在端粒DNA结合蛋白Cdc13p的募集作用下发挥作用。与该模型一致的是，我们发现此时Est1p、Est2p和Cdc13p与端粒相关。然而，Est2p而非Est1p在S期晚期之前也会结合端粒。有人提出cdc13 - 2等位基因在募集过程中存在缺陷，但Est1p和Est2p与端粒的结合在cdc13 - 2细胞中仍然持续存在。这些发现提示了一种模型，即Est1p在S期晚期结合端粒，并与Cdc13p相互作用，将无活性的、结合在端粒上的Est2p转化为活性形式。
