STRUCTURE-FUNCTION OF THE ACTIN CYTOSKELETON

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肌动蛋白细胞骨架在多种细胞功能中发挥着重要作用，包括胞质分裂、囊泡运输以及维持细胞形态和极性。这些过程的驱动力是肌动蛋白细胞骨架动态重塑为超分子功能网络，这一过程在细胞内受到严格调控，涉及数百个肌动蛋白结合和信号蛋白。我们实验室的一些项目旨在了解肌动蛋白细胞骨架动力学的分子机制。其中一些项目涉及在BioCAT收集SAXS/WAXS数据，包括： 含WH2蛋白的肌动蛋白微丝成核机制。WASP同源结构域2(WH2)是一个丰富的肌动蛋白结合基序，存在于许多参与肌动蛋白细丝成核和伸长的蛋白质中。基于我们的WH2-肌动蛋白的结构(Chereau等人，PNAS 2005)，我们提出了串联的WH2结构域沿着一条丝链排列肌动蛋白亚基，形成细胞核进行肌动蛋白组装。为了验证这一假设，我们正在研究通过串联WH2结构域组装的肌动蛋白微丝的结构。 Arp2/3复合体对肌动蛋白微丝成核的作用机制。Arp2/3复合体是一种肌动蛋白细丝成核机制，由七种蛋白质组成，其中两种与肌动蛋白相关(Arp2和Arp3)。Arp2和Arp3被认为与肌动蛋白亚基结合在一起形成一个三聚体聚合种子，该亚基结合到激活Arp2/3的许多成核促进因子蛋白之一的WH2结构域，如WASP。为了了解Arp2/3复合体成核的机制，我们正在研究一个由WASP+肌动蛋白+Arp2/3-复合体组成的9蛋白复合体的结构。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The actin cytoskeleton plays an essential role in multiple cellular functions, including cytokinesis, vesicular trafficking and the maintenance of cell shape and polarity. The driving force for these processes is the dynamic remodeling of the actin cytoskeleton into supramolecular functional networks, a process that is a tightly regulated in the cell and involves hundreds of actin-binding and signaling proteins. A number of projects in our lab aim to understand the molecular mechanisms of actin cytoskeleton dynamics. Some of these projects involve SAXS/WAXS data collection at BioCAT, including: Mechanism of actin filament nucleation by WH2 containing proteins. The WASP homology domain 2 (WH2) is an abundant actin-binding motif found in many proteins involved in actin filament nucleation and elongation. Based on our structures of WH2-actin (Chereau et al., PNAS 2005) we proposed that tandem WH2 domains line up actin subunits along a filament strand forming nuclei for actin assembly. To test this hypothesis we are working on the structures of actin minifilaments assembled via tandem WH2 domains constructs. Mechanism of actin filament nucleation by Arp2/3 complex. Arp2/3 complex, is an actin filament nucleation machinery, consisting of seven proteins, two of which are related to actin (Arp2 and Arp3). Arp2 and Arp3 are thought to form a trimeric polymerization seed together with an actin subunit bound to a WH2 domain of one of the many nucleation-promoting factor protein that activate Arp2/3, such as WASP. To understand the mechanism of filament nucleation by Arp2/3 complex, we are working on the structure of a 9 protein complex consisting of WASP + actin + Arp2/3-complex.