多聚（A）结合蛋白 Pab1p 在 PUF 蛋白介导的抑制中的作用。
A role for the poly(A)-binding protein Pab1p in PUF protein-mediated repression.
机构信息
Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
出版信息
J Biol Chem. 2011 Sep 23;286(38):33268-78. doi: 10.1074/jbc.M111.264572. Epub 2011 Jul 15.
PUF proteins regulate translation and mRNA stability throughout eukaryotes. Using a cell-free translation assay, we examined the mechanisms of translational repression of PUF proteins in the budding yeast Saccharomyces cerevisiae. We demonstrate that the poly(A)-binding protein Pab1p is required for PUF-mediated translational repression for two distantly related PUF proteins: S. cerevisiae Puf5p and Caenorhabditis elegans FBF-2. Pab1p interacts with oligo(A) tracts in the HO 3'-UTR, a target of Puf5p, to dramatically enhance the efficiency of Puf5p repression. Both the Pab1p ability to activate translation and interact with eukaryotic initiation factor 4G (eIF4G) were required to observe maximal repression by Puf5p. Repression was also more efficient when Pab1p was bound in close proximity to Puf5p. Puf5p may disrupt translation initiation by interfering with the interaction between Pab1p and eIF4G. Finally, we demonstrate two separable mechanisms of translational repression employed by Puf5p: a Pab1p-dependent mechanism and a Pab1p-independent mechanism.
PUF 蛋白在真核生物中调节翻译和 mRNA 稳定性。我们使用无细胞翻译测定法，研究了 PUF 蛋白在酿酒酵母（Saccharomyces cerevisiae）中的翻译抑制机制。我们证明，多聚（A）结合蛋白 Pab1p 对于两种远缘 PUF 蛋白 S. cerevisiae Puf5p 和秀丽隐杆线虫（Caenorhabditis elegans）FBF-2 的 PUF 介导的翻译抑制是必需的。Pab1p 与 HO 3'-UTR 中的 oligo(A) 序列相互作用，这是 Puf5p 的靶标，从而极大地增强了 Puf5p 抑制的效率。观察到 Puf5p 的最大抑制作用，需要 Pab1p 具有激活翻译的能力和与真核起始因子 4G（eIF4G）相互作用的能力。当 Pab1p 紧密结合 Puf5p 时，抑制作用也更加有效。Puf5p 可能通过干扰 Pab1p 和 eIF4G 之间的相互作用来破坏翻译起始。最后，我们证明了 Puf5p 采用两种可分离的翻译抑制机制：一种依赖 Pab1p 的机制和一种不依赖 Pab1p 的机制。
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