Synergism of the Two Myb Domains of Tay1 Protein Results in High Affinity Binding to Telomeres
Synergism of the Two Myb Domains of Tay1 Protein Results in High Affinity Binding to Telomeres
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DOI：
10.1074/jbc.m112.385591
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发表时间：
2012-09-14
影响因子：
4.8
通讯作者：
Tomaska, Lubomir
中科院分区：
文献类型：
--
作者：
Visacka, Katarina;Hofr, Ctirad;Tomaska, Lubomir
端粒的双链区域被含有myb样结构域的蛋白质识别，赋予端粒重复序列的特异性。尽管生物化学和结构研究揭示了DNA结合的基本分子原理，但对于真核生物不同物种中各种类型Myb结构域蛋白的进化途径知之甚少。最近，我们从酵母菌脂溶耶氏菌中发现了一种新型的端粒结合蛋白YlTay1p，它含有两个Myb结构域（Myb1, Myb2），与哺乳动物TRF1和TRF2的Myb结构域非常相似。在这项研究中，我们制备了缺乏Myb1、Myb2或两个Myb结构域的YlTay1p突变体，发现携带Myb结构域的YlTay1p对脂肪瘤（GGGTTAGTCA）(n)和人类（TTAGGG）(n)端粒序列都具有优先亲和力。蛋白质与端粒DNA结合的定量测量显示，Myb结构域的存在是YlTay1p与任一端粒重复的高亲和力所必需的。此外，我们对YlTay1p与其同源端粒DNA的相互作用进行了详细的热力学分析，据我们所知，这是第一次对全长端粒蛋白与DNA结合的能量描述。有趣的是，与人类TRF1和TRF2蛋白相比，YlTay1p不仅对脂肪瘤的端粒有更高的亲和力，而且对人类端粒序列也有更高的亲和力。因此，YlTay1p中Myb结构域的重复对其对同源端粒序列的亲和力产生了协同效应，减轻了在具有单个Myb结构域的trf样蛋白中观察到的同二聚化的需要。
Double-stranded regions of the telomeres are recognized by proteins containing Myb-like domains conferring specificity toward telomeric repeats. Although biochemical and structural studies revealed basic molecular principles involved in DNA binding, relatively little is known about evolutionary pathways leading to various types of Myb domain-containing proteins in divergent species of eukaryotes. Recently we identified a novel type of telomere-binding protein YlTay1p from the yeast Yarrowia lipolytica containing two Myb domains (Myb1, Myb2) very similar to the Myb domain of mammalian TRF1 and TRF2. In this study we prepared mutant versions of YlTay1p lacking Myb1, Myb2, or both Myb domains and found that YlTay1p carrying either Myb domain exhibits preferential affinity to both Y. lipolytica (GGGTTAGTCA)(n) and human (TTAGGG)(n) telomeric sequences. Quantitative measurements of the protein binding to telomeric DNA revealed that the presence of both Myb domains is required for a high affinity of YlTay1p to either telomeric repeat. Additionally, we performed detailed thermodynamic analysis of the YlTay1p interaction with its cognate telomeric DNA, which is to our knowledge the first energetic description of a full-length telomeric-protein binding to DNA. Interestingly, when compared with human TRF1 and TRF2 proteins, YlTay1p exhibited higher affinity not only for Y. lipolytica telomeres but also for human telomeric sequences. The duplication of the Myb domain region in YlTay1p thus produces a synergistic effect on its affinity toward the cognate telomeric sequence, alleviating the need for homodimerization observed in TRF-like proteins possessing a single Myb domain.