The role of PAM2 proteins during polar growth of U. maydis

玉米黑粉菌花丝的极地生长依赖于mRNAs的长距离运输。关键的RNA结合蛋白Rrm4作为核糖核蛋白(MRNP)复合体的一部分运输不同组的mRNAs。相应的mRNAs编码极性因子，如小G蛋白Rho3和Septin CDc3以及线粒体蛋白。在rrm4Δ菌株中，菌丝顶端cdc3的极性积累受到干扰，表明靶mRNAs的运输决定了编码蛋白的正确亚细胞定位。虽然核糖核酸结合蛋白及其货物mRNAs是已知的，但确切的转运机制(S)仍然不清楚。在这里，我们的目的是研究含有RRM4的mRNPs的蛋白质组成，以进一步阐明mRNPs的机制(S)。由于Rrm4是运输mRNPs不可或缺的一部分，它将被用作纯化相关成分的分子手柄。有趣的候选者将被进一步表征以揭示它们的功能，例如在RNA结合期间以及在mRNP复合体的形成和移动期间。这些研究将有助于对新的贩运成分进行识别和功能分类，并为真核生物极地生长的生物学过程提供更深层次的见解。

Polar growth of filaments of Ustilago maydis depends on long-distance transport of mRNAs. The key RNA-binding protein Rrm4 transports distinct sets of mRNAs as part of ribonucleoprotein (mRNP) complexes. Corresponding mRNAs encode polarity factors e.g. the small G protein Rho3 and the septin Cdc3 as well as mitochondrial proteins. Polar accumulation of Cdc3 at hyphal tips is disturbed in rrm4Δ strains, indicating that transport of target mRNAs determines the correct subcellular localisation of encoded proteins. Although the RNA-binding protein and its cargo mRNAs are known, the exact mechanism(s) of transport remains elusive. Here, we aim to investigate the protein composition of Rrm4- containing mRNPs to further elucidate the mechanism(s) of mRNA trafficking. Since Rrm4 is an integral part of transport mRNPs, it will be used as a molecular handle to purify associated components. Interesting candidates will be further characterised to uncover their function e.g. during RNA binding as well as during formation and movement of mRNP complexes. These studies will allow the identification and functional classification of novel trafficking components and provide deeper insights into the biological processes underlying polar growth in eukaryotes.