Biozentrum, Universität Basel, Switzerland.
EMBO J. 2011 Jul 26;30(17):3567-80. doi: 10.1038/emboj.2011.247.
In budding yeast, several mRNAs are selectively transported into the daughter cell in an actin-dependent manner by a specialized myosin system, the SHE machinery. With ABP140 mRNA, we now describe the first mRNA that is transported in the opposite direction and localizes to the distal pole of the mother cell, independent of the SHE machinery. Distal pole localization is not observed in mutants devoid of actin cables and can be disrupted by latrunculin A. Furthermore, localization of ABP140 mRNA requires the N-terminal actin-binding domain of Abp140p to be expressed. By replacing the N-terminal localization motif, ABP140 mRNA can be retargeted to different subcellular structures. In addition, accumulation of the mRNA at the distal pole can be prevented by disruption of polysomes. Using the MS2 system, the mRNA was found to associate with actin cables and to follow actin cable dynamics. We therefore propose a model of translational coupling, in which ABP140 mRNA is tethered to actin cables via its nascent protein product and is transported to the distal pole by actin retrograde flow.
在芽殖酵母中，几种 mRNA 被一种特殊的肌球蛋白系统（SHE 机器）以依赖于肌动蛋白的方式有选择地运输到子细胞中。现在，我们用 ABP140 mRNA 描述了第一个以相反方向运输并定位于母细胞远端极的 mRNA，该过程独立于 SHE 机器。在缺乏肌动蛋白纤维的突变体中观察不到远端极定位，Latrunculin A 可以破坏这种定位。此外，ABP140 mRNA 的定位需要表达 Abp140p 的 N 端肌动蛋白结合结构域。通过替换 N 端定位基序，ABP140 mRNA 可以被重新靶向到不同的亚细胞结构。此外，通过破坏多核糖体，可以防止 mRNA 在远端极的积累。使用 MS2 系统，发现该 mRNA 与肌动蛋白纤维结合，并跟随肌动蛋白纤维的动力学。因此，我们提出了一个翻译偶联模型，其中 ABP140 mRNA 通过其新生蛋白质产物与肌动蛋白纤维相连，并通过肌动蛋白逆行流被运输到远端极。
