The RNA-Binding Protein Rrm4 is Essential for Efficient Secretion of Endochitinase Cts1
The RNA-Binding Protein Rrm4 is Essential for Efficient Secretion of Endochitinase Cts1
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DOI：
10.1074/mcp.m111.011213
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发表时间：
2011-12-01
影响因子：
7
通讯作者：
Feldbruegge, Michael
中科院分区：
文献类型：
--
作者：
Koepke, Janine;Kaffarnik, Florian;Feldbruegge, Michael
mRNA 的长距离运输对于确定真核生物中的时空基因表达至关重要。 RNA 结合蛋白 Rrm4 是玉米黑粉菌丝中微管依赖性 mRNA 运输的关键成分。尽管可以鉴定出许多潜在的靶标 mRNA，但依赖 Rrm4 介导的转运的细胞过程仍然很大程度上未知。在这里，我们使用差异蛋白质组学来证明核糖体、线粒体和细胞壁重塑蛋白（包括细菌型内切壳多糖酶 Cts1）在 rrm4 Delta 丝中受到差异调节。体内紫外交联、免疫沉淀和荧光原位杂交表明，cts1 mRNA 是 Rrm4 的直接靶标。 cts1 Delta 突变体的细丝在液体培养物中聚集，表明细胞表面发生了改变。在野生型细胞中，Cts1 主要定位于生长锥，而它在 rrm4 Delta 丝的两个极处积累。内切壳多糖酶被分泌并最有可能与细丝的细胞壁结合。缺乏 Rrm4 或传统驱动蛋白 Kin1 的丝状体以及微管破坏的丝状体的分泌受到严重损害。因此，Rrm4 介导的 mRNA 转运似乎对于活性 Cts1 的有效输出至关重要，揭示了 mRNA 转运和分泌机制之间的新分子联系。分子与细胞蛋白质组学 10：10.1074/mcp.M111.011213，1-15，2011。
Long-distance transport of mRNAs is crucial in determining spatio-temporal gene expression in eukaryotes. The RNA-binding protein Rrm4 constitutes a key component of microtubule-dependent mRNA transport in filaments of Ustilago maydis. Although a number of potential target mRNAs could be identified, cellular processes that depend on Rrm4-mediated transport remain largely unknown. Here, we used differential proteomics to show that ribosomal, mitochondrial, and cell wall-remodeling proteins, including the bacterial-type endochitinase Cts1, are differentially regulated in rrm4 Delta filaments. In vivo UV crosslinking and immunoprecipitation and fluorescence in situ hybridization revealed that cts1 mRNA represents a direct target of Rrm4. Filaments of cts1 Delta mutants aggregate in liquid culture suggesting an altered cell surface. In wild type cells Cts1 localizes predominantly at the growth cone, whereas it accumulates at both poles in rrm4 Delta filaments. The endochitinase is secreted and associates most likely with the cell wall of filaments. Secretion is drastically impaired in filaments lacking Rrm4 or conventional kinesin Kin1 as well as in filaments with disrupted microtubules. Thus, Rrm4-mediated mRNA transport appears to be essential for efficient export of active Cts1, uncovering a novel molecular link between mRNA transport and the mechanism of secretion. Molecular & Cellular Proteomics 10: 10.1074/mcp.M111.011213, 1-15, 2011.