STRUCTURE-FUNCTION OF THE ACTIN CYTOSKELETON

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 肌动蛋白细胞骨架在多种细胞功能中起重要作用，包括胞质分裂、囊泡运输以及维持细胞形状和极性。这些过程的驱动力是肌动蛋白细胞骨架动态重塑成超分子功能网络，这是一个在细胞中受到严格调控的过程，涉及数百种肌动蛋白结合和信号蛋白。我们实验室的许多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BioCAT的SAXS/WAXS数据收集，包括： 含WH 2蛋白的肌动蛋白丝成核机制。WASP同源结构域2（WH 2）是一个丰富的肌动蛋白结合基序，发现在许多蛋白质参与肌动蛋白丝成核和延伸。基于我们的WH 2-肌动蛋白的结构（Chereau等人，PNAS 2005），我们提出串联的WH 2结构域使肌动蛋白亚基沿着形成用于肌动蛋白组装的核的细丝链排列。为了验证这一假设，我们正在研究通过串联WH 2结构域构建的肌动蛋白微丝的结构。 Arp 2/3复合物对肌动蛋白丝成核的机制Arp 2/3复合物是一种肌动蛋白丝成核机制，由7种蛋白质组成，其中两种与肌动蛋白有关（Arp 2和Arp 3）。Arp 2和Arp 3被认为与肌动蛋白亚基一起形成三聚体聚合种子，所述肌动蛋白亚基结合到激活Arp 2/3的许多成核促进因子蛋白之一（例如WASP）的WH 2结构域。为了理解Arp 2/3复合物的成核机制，我们正在研究由WASP + actin + Arp 2/3-复合物组成的9蛋白复合物的结构。

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.