The long-term goal of this program project is to understand the molecular mechanisms that allow Arp2/3 complex to control actin filament assembly during endocytosis and cellular motility. The mechanism of action of Arp2/3 complex is so complicated that a team effort is required. Our group of four geographically dispersed laboratories combines x-ray crystallography, electron microscopy, image processing and molecular biology to address technically challenging questions. Structural insights from his ongoing collaboration will provide important clues about reaction mechanisms and also help to design experiments to measure kinetic and thermodynamic constants and to study actin assembly in live cells. Project 1 (Pollard) proposes a combination of biochemical and x-ray crystallographic experiments to obtain detailed structural information regarding conformational changes and macromolecular interactions of Arp2/3 complex. Project 2 (Li) proposes a combination of biophysical studies on interaction's of nucleation promoting factors with purified Arp2/3 complex and microscopic analysis of mouse cells lacking subunits of Arp2/3 complex. Project 3 (Hanein) proposes electron microscopy of purified Arp2/3 complex, actin filament branches and of actin networks in mouse cells with and without functional Arp2/3 complex. Project 4 (Volkmann) proposes computational methods to extract the maximal amount of information from spectroscopy experiments in projects 1 and 2 and the electron micrographs from project 3.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Program Projects (P01)
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Special Emphasis Panel (ZRG1-CB-D (40))
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Gindhart, Joseph G
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Yale University
Schools of Arts and Sciences
New Haven
United States
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Volkmann, Niels (2014) The joys and perils of flexible fitting. Adv Exp Med Biol 805:137-55
Volkmann, Niels; Page, Christopher; Li, Rong et al. (2014) Three-dimensional reconstructions of actin filaments capped by Arp2/3 complex. Eur J Cell Biol 93:179-83
Xu, Xiao-Ping; Slaughter, Brian D; Volkmann, Niels (2013) Probabilistic determination of probe locations from distance data. J Struct Biol 184:75-82
Xu, X-P; Zhai, D; Kim, E et al. (2013) Three-dimensional structure of Bax-mediated pores in membrane bilayers. Cell Death Dis 4:e683
Yi, Kexi; Rubinstein, Boris; Li, Rong (2013) Symmetry breaking and polarity establishment during mouse oocyte maturation. Philos Trans R Soc Lond B Biol Sci 368:20130002
Li, Rong; Albertini, David F (2013) The road to maturation: somatic cell interaction and self-organization of the mammalian oocyte. Nat Rev Mol Cell Biol 14:141-52
Pollard, Thomas D; De La Cruz, Enrique M (2013) Take advantage of time in your experiments: a guide to simple, informative kinetics assays. Mol Biol Cell 24:1103-10
Yi, Kexi; Rubinstein, Boris; Unruh, Jay R et al. (2013) Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes. J Cell Biol 200:567-76
Volkmann, Niels (2012) Putting structure into context: fitting of atomic models into electron microscopic and electron tomographic reconstructions. Curr Opin Cell Biol 24:141-7
Suraneni, Praveen; Rubinstein, Boris; Unruh, Jay R et al. (2012) The Arp2/3 complex is required for lamellipodia extension and directional fibroblast cell migration. J Cell Biol 197:239-51

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