Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA.
Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912, USA.
Dev Biol. 2021 Oct;478:76-88. doi: 10.1016/j.ydbio.2021.06.009. Epub 2021 Jun 25.
Egalitarian (Egl) is an RNA adaptor for the Dynein motor and is thought to link numerous, perhaps hundreds, of mRNAs with Dynein. Dynein, in turn, is responsible for the transport and localization of these mRNAs. Studies have shown that efficient mRNA binding by Egl requires the protein to dimerize. We recently demonstrated that Dynein light chain (Dlc) is responsible for facilitating the dimerization of Egl. Mutations in Egl that fail to interact with Dlc do not dimerize, and as such, are defective for mRNA binding. Consequently, this mutant does not efficiently associate with BicaudalD (BicD), the factor responsible for linking the Egl/mRNA complex with Dynein. In this report, we tested whether artificially dimerizing this Dlc-binding mutant using a leucine zipper would restore mRNA binding and rescue mutant phenotypes in vivo. Interestingly, we found that although artificial dimerization of Egl restored BicD binding, it only partially restored mRNA binding. As a result, Egl-dependent phenotypes, such as oocyte specification and mRNA localization, were only partially rescued. We hypothesize that Dlc-mediated dimerization of Egl results in a three-dimensional conformation of the Egl dimer that is best suited for mRNA binding. Although the leucine zipper restores Egl dimerization, it likely does not enable Egl to assemble into the conformation required for maximal mRNA binding activity.
平等主义者（Egl）是一种与动力蛋白结合的 RNA 衔接子，被认为可以将许多（也许是数百个）mRNA 与动力蛋白联系起来。动力蛋白反过来又负责这些 mRNA 的运输和定位。研究表明，Egl 与 mRNA 的有效结合需要蛋白质二聚化。我们最近证明，Dynein 轻链（Dlc）负责促进 Egl 的二聚化。无法与 Dlc 相互作用的 Egl 突变体不能二聚化，因此，不能有效地结合 mRNA。因此，这种突变体不能有效地与 BicaudalD（BicD）结合，BicD 是负责将 Egl/mRNA 复合物与动力蛋白连接的因子。在本报告中，我们测试了使用亮氨酸拉链人为地二聚化这种与 Dlc 结合的突变体是否可以恢复 mRNA 结合并在体内挽救突变体表型。有趣的是，我们发现尽管 Egl 的人工二聚化恢复了 BicD 的结合，但它只部分恢复了 mRNA 的结合。因此，Egl 依赖性表型，如卵母细胞的特化和 mRNA 的定位，仅部分得到挽救。我们假设 Dlc 介导的 Egl 二聚化导致 Egl 二聚体的三维构象最适合 mRNA 结合。尽管亮氨酸拉链恢复了 Egl 的二聚化，但它可能不能使 Egl 组装成最适合最大 mRNA 结合活性的构象。
