DNA Binding Induces Dimerization of Saccharomyces cerevisiae Pif1
DNA Binding Induces Dimerization of Saccharomyces cerevisiae Pif1
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DOI：
10.1021/bi100984j
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发表时间：
2010-10-05
期刊：
影响因子：
2.9
通讯作者：
Galletto, Roberto
中科院分区：
文献类型：
--
作者：
Barranco-Medina, Sergio;Galletto, Roberto
在酿酒酵母中，Pif1参与了广泛的DNA交易。它在线粒体和细胞核中都有作用，在细胞核中它有端粒和非端粒的功能。Pif1的所有活性都依赖于它与DNA结合的能力。我们已经确定了Pif1与不同DNA底物结合的模式。虽然Pif1在溶液中是一个单体，但我们发现ssDNA与Pif1结合可诱导蛋白质二聚化。dna诱导的Pif1二聚化也可以在尾状和叉状dsdna底物上观察到，这表明Pif1二聚体的形成可以阻止其他Pif1分子的结合。Pif1的二聚体也在随机组成的ssDNA上形成，并且存在饱和浓度的不可水解ATP类似物。在ATP类似物存在的情况下，在解绕底物上形成了Pill二聚体，这表明酶的二聚体形式可能构成了导致其解绕活性的起始前复合物。
In Saccharomyces cerevisiae, Pif1 is involved in a wide range of DNA transactions. It operates both in mitochondria and in the nucleus, where it has telomeric and non-telomeric functions. All of the activities of Pif1 rely on its ability to bind to DNA. We have determined the mode of Pif1 binding to different DNA substrates. While Pif1 is a monomer in solution, we show that binding of ssDNA to Pif1 induces protein dimerization. DNA-induced dimerization of Pif1 is also observed on tailed- and forked-dsDNA substrates, suggesting that on the latter formation of a Pif1 dimer prevents binding of additional Pif1 molecules. A dimer of Pif1 also forms on ssDNA of random composition and in the presence of saturating concentrations of nonhydrolyzable ATP analogues. The observation that a Pill dimer is formed on unwinding substrates in the presence of ATP analogues suggests that a dimeric form of the enzyme might constitute the pre-initiation complex leading to its unwinding activity.