Association of the Yeast RNA-binding Protein She2p with the Tubular Endoplasmic Reticulum Depends on Membrane Curvature
Association of the Yeast RNA-binding Protein She2p with the Tubular Endoplasmic Reticulum Depends on Membrane Curvature
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DOI：
10.1074/jbc.m113.486431
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发表时间：
2013-11-08
影响因子：
4.8
通讯作者：
Jansen, Ralf-Peter
中科院分区：
文献类型：
--
作者：
Genz, Christian;Fundakowski, Julia;Jansen, Ralf-Peter
mRNA的定位有助于在广泛的生物体中产生和维持细胞不对称性。在酿酒酵母中，具有其核心组分Myo4p、She2p和She3p的所谓定位体复合物将30多种mRNA定位于酵母芽尖。这些mRNA的显著部分编码膜或分泌蛋白。它们的定位需要，除了locasome，皮质内质网（ER）的功能分离装置，包括在ER小管进入芽的运动所涉及的机械。含有RNA的颗粒与这些小管的共定位表明了局部mRNA和皮质ER向芽的协调运输。局部mRNA与ER的结合需要局部酶体组分She2p的存在。在这里，我们报告说，She2p不仅是一种RNA结合蛋白，但可以特异性结合ER衍生的膜在体外膜曲率依赖的方式。虽然它不包含任何已知的曲率识别基序，该蛋白质显示出对直径类似于酵母ER小管的脂质体的结合偏好。此外，膜结合依赖于She2p的四聚化。在体内膜束缚测定中，She2p可以将病毒肽GFP融合蛋白靶向皮质ER，表明She2p的一部分与体内ER相关联。结合RNA和膜结合的功能使She2p成为ER小管和mRNA共转运的理想协调者。
Localization of mRNAs contributes to the generation and maintenance of cellular asymmetry in a wide range of organisms. In Saccharomyces cerevisiae, the so-called locasome complex with its core components Myo4p, She2p, and She3p localizes more than 30 mRNAs to the yeast bud tip. A significant fraction of these mRNAs encodes membrane or secreted proteins. Their localization requires, besides the locasome, a functional segregation apparatus of the cortical endoplasmic reticulum (ER), including the machinery that is involved in the movement of ER tubules into the bud. Colocalization of RNA-containing particles with these tubules suggests a coordinated transport of localized mRNAs and the cortical ER to the bud. Association of localized mRNAs to the ER requires the presence of the locasome component She2p. Here we report that She2p is not only an RNA-binding protein but can specifically bind to ER-derived membranes in a membrane curvature-dependent manner in vitro. Although it does not contain any known curvature recognizing motifs, the protein shows a binding preference for liposomes with a diameter resembling that of yeast ER tubules. In addition, membrane binding depends on tetramerization of She2p. In an in vivo membrane-tethering assay, She2p can target a viral peptide GFP fusion protein to the cortical ER, indicating that a fraction of She2p associates with the ER in vivo. Combining RNA- and membrane-binding features makes She2p an ideal coordinator of ER tubule and mRNA cotransport.