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Molecular Mechanisms underlying selection of cargo, scission, and coat release of intracellular vesicular carriers

细胞内囊泡载体的货物选择、分裂和外壳释放的分子机制

基本信息

批准号：
287901311
负责人：
Professor Dr. Felix Wilhelm Theodor Wieland
金额：
--
依托单位：
Biochemie-Zentrum (BZH)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/287901311?language=en
关键词：
Molecular Mechanisms underlying selection cargo

项目摘要

In eukaryotes, protein-coated vesicular carriers mediate intracellular transport of membranes and proteins. We are interested in the structure and the molecular mechanisms that underlie the formation and function of such vesicles, their selective incorporation of protein and lipid cargo, and their un-coating. We have previously defined the minimal protein machinery that is necessary and sufficient to form COPI vesicles through reconstitution studies with recombinant coat proteins and defined liposomes. Whereas basic structural elements resemble each other in a variety of coat protein subunits that form COPI-, COPII-, and Clathrin-coated vesicles (CCVs), the overall structure of the COPI coat is different from the other established coats. This structural divergence might reflect different mechanisms for the uptake of cargo molecules into these carriers. Moreover, unlike the COPII and Clathrin coats that form stepwise, the COPI coat is recruited to the donor membrane in a single step. Yet, the mechanisms of coat recruitment, and possibly of membrane scission, share certain similarities among all classes of vesicular carriers. Driven by structural insight into the COPI coat, in this application we propose to investigate i) the structural basis for the COPI scission reaction, and whether a general mechanism exists that applies for all membrane scission events catalyzed by small GTP-binding proteins, ii) the selectivity of different COPI and COPII coat protein isoforms for the uptake of protein and membrane lipid cargo, and iii) how GTPase-activating proteins catalyze the removal of the COPI coat and possibly aid coatomer to be recycled to its soluble form.

在真核生物中，蛋白质包被的囊泡载体介导膜和蛋白质的细胞内转运。我们感兴趣的是这种囊泡的形成和功能的结构和分子机制，它们选择性地掺入蛋白质和脂质货物，以及它们的非涂层。我们以前已经定义了最小的蛋白质机器，这是必要的和足够的，以形成COPI囊泡，通过重组外壳蛋白和确定的脂质体重建研究。而基本的结构元素在形成COPI-，COPII-和网格蛋白包被囊泡（CCV）的各种外壳蛋白亚基中彼此相似，COPI外壳的整体结构与其他已建立的外壳不同。这种结构上的差异可能反映了货物分子摄取到这些载体中的不同机制。此外，与逐步形成的COPII和网格蛋白涂层不同，COPI涂层在单个步骤中被募集到供体膜。然而，在所有类型的囊泡载体中，被膜募集和可能的膜断裂的机制具有某些相似性。通过对COPI外壳的结构洞察，在本申请中，我们提出研究i）COPI断裂反应的结构基础，以及是否存在适用于由小GTP结合蛋白催化的所有膜断裂事件的一般机制，ii）不同COPI和COPII外壳蛋白同种型对蛋白质和膜脂质货物摄取的选择性，和iii）GTP酶活化蛋白如何催化COPI包衣的去除并可能帮助包衣体再循环至其可溶形式。