In vitro reconstitution of an mRNA-transport complex reveals mechanisms of assembly and motor activation.
In vitro reconstitution of an mRNA-transport complex reveals mechanisms of assembly and motor activation.
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DOI：
10.1083/jcb.201302095
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发表时间：
2013-12-23
期刊：
影响因子：
--
通讯作者：
Niessing D
中科院分区：
文献类型：
--
作者：
Heym RG;Zimmermann D;Edelmann FT;Israel L;Ökten Z;Kovar DR;Niessing D
萌芽酵母SHE mRNA转运复合体二聚体激活进行性RNA转运，而与RNA货物的存在无关，并在与多个定位元件结合RNA时多聚体。不对称信使RNA(MRNA)定位的核糖核酸(RNA)转运颗粒的组装和组成尚不清楚。在发芽酵母的有丝分裂过程中，Swi5p依赖的HO表达(SHE)复合体将一组mRNAs转运到子细胞中。我们重组了核心SHE复合体，并对其性质进行了评估。细胞质前复合体只含有一个马达，不能支持连续运输。然而，在其核出口后，与第二个RNA结合的前复合体的明确相互作用会使发动机二聚化并激活过程中的RNA运输。体外观察到的运行长度与体内的长距离传输是兼容的。令人惊讶的是，含有或不含有RNA货物的SHE复合体表现出类似的运动性，表明激活运动性的是RNA结合蛋白而不是它的货物。我们进一步证明了SHE络合物有一定的大小，但当RNA与多个局域元件结合时，SHE络合物会多聚化成不同的粒子。基于这些发现，我们提供了细胞中这种多聚体SHE粒子的数量、大小和组成的估计。
The budding yeast SHE mRNA-transport complex dimerizes to activate processive RNA transport, irrespective of the presence of RNA cargo, and multimerizes upon binding RNAs with multiple localization elements. The assembly and composition of ribonucleic acid (RNA)–transporting particles for asymmetric messenger RNA (mRNA) localization is not well understood. During mitosis of budding yeast, the Swi5p-dependent HO expression (SHE) complex transports a set of mRNAs into the daughter cell. We recombinantly reconstituted the core SHE complex and assessed its properties. The cytoplasmic precomplex contains only one motor and is unable to support continuous transport. However, a defined interaction with a second, RNA-bound precomplex after its nuclear export dimerizes the motor and activates processive RNA transport. The run length observed in vitro is compatible with long-distance transport in vivo. Surprisingly, SHE complexes that either contain or lack RNA cargo show similar motility properties, demonstrating that the RNA-binding protein and not its cargo activates motility. We further show that SHE complexes have a defined size but multimerize into variable particles upon binding of RNAs with multiple localization elements. Based on these findings, we provide an estimate of number, size, and composition of such multimeric SHE particles in the cell.
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作者：
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影响因子：
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DOI：
10.1073/pnas.0509229102
发表时间：
2005-12-13
影响因子：
11.1
作者：
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通讯作者：
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