Counting of Rif1p and Rif2p on Saccharomyces cerevisiae telomeres regulates telomere length
Counting of Rif1p and Rif2p on Saccharomyces cerevisiae telomeres regulates telomere length
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DOI：
10.1128/mcb.24.24.10857-10867.2004
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发表时间：
2004-12-01
影响因子：
5.3
通讯作者：
Blackburn, EH
中科院分区：
文献类型：
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作者：
Levy, DL;Blackburn, EH
端粒长度受端粒DNA-蛋白质复合体的蛋白质负调控。酿酒酵母中的Rap1p与端粒Tg(1-3)重复序列DNA结合，Rap1p的C末端与Rif1p和Rif2p相互作用。我们研究了这三种蛋白质如何负向调节端粒长度。我们表明，将每个Rif蛋白直接拴在端粒上，端粒的长度与被拴住的分子的数量成比例，类似于之前报道的Rap1p的计数。令人惊讶的是，Rif蛋白也可以调节端粒长度，即使在没有Rap1p C末端的情况下，而且拴系的Rap1p计数完全依赖于Rif蛋白。因此，Rap1p计数实际上是Rif蛋白质计数。在导致端粒异常长的遗传环境中，即使是一个单独的Rif2p分子也足以最有效地防止端粒过度延长。我们发现，当与Rap1p融合时，一个异源的蛋白质齐聚结构域，哺乳动物的PDZ结构域，可以提供端粒长度控制。我们认为，核化和扩散机制参与了调节端粒长度的高阶端粒结构的形成。
Telomere length is negatively regulated by proteins of the telomeric DNA-protein complex. Rap1p in Saccharomyces cerevisiae binds the telomeric TG(1-3) repeat DNA, and the Rap1p C terminus interacts with Rif1p and Rif2p. We investigated how these three proteins negatively regulate telomere length. We show that direct tethering of each Rif protein to a telomere shortens that telomere proportionally to the number of tethered molecules, similar to previously reported counting of Rap1p. Surprisingly, Rif proteins could also regulate telomere length even when the Rap1p C terminus was absent, and tethered Rap1p counting was completely dependent on the Rif proteins. Thus, Rap1p counting is in fact Rif protein counting. In genetic settings that cause telomeres to be abnormally long, tethering even a single Rif2p molecule was sufficient for maximal effectiveness in preventing the telomere overelongation. We show that a heterologous protein oligomerization domain, the mammalian PDZ domain, when fused to Rap1p can confer telomere length control. We propose that a nucleation and spreading mechanism is involved in forming the higher-order telomere structure that regulates telomere length.