The Ever shorter telomeres 3 (Est3) protein is a small regulatory subunit of yeast telomerase which is dispensable for enzyme catalysis but essential for telomere replication in vivo. Using structure prediction combined with in vivo characterization, we show here that Est3 consists of a predicted OB (oligosaccharide/oligonucleotide binding)-fold. We used mutagenesis of predicted surface residues to generate a functional map of one surface of Est3, identifying a site that mediates association with the telomerase complex. Unexpectedly, the predicted OB-fold of Est3 is structurally similar to the OB-fold of the human TPP1 protein, despite the fact that Est3 and TPP1, as components of telomerase and a telomere-capping complex, respectively, perform functionally distinct tasks at chromosome ends. Our analysis of Est3 may be instructive in generating comparable missense mutations on the surface of the OB-fold domain of TPP1.

中文翻译：

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Est3 蛋白通过 OB 折叠结构域与酵母端粒酶结合。

更短的端粒 3 (Est3) 蛋白是酵母端粒酶的一个小的调节亚基，它对于酶催化是可有可无的，但对于体内端粒复制是必不可少的。使用结构预测与体内表征相结合，我们在此显示 Est3 由预测的 OB（寡糖/寡核苷酸结合）折叠组成。我们使用预测表面残基的诱变来生成 Est3 一个表面的功能图，确定一个介导与端粒酶复合物结合的位点。出乎意料的是，Est3 的预测 OB 折叠在结构上与人类 TPP1 蛋白的 OB 折叠相似，尽管事实上 Est3 和 TPP1 作为端粒酶和端粒封端复合物的组分，分别在染色体上执行功能不同的任务结束。