Actin crystal dynamics: structural implications for F-actin nucleation, polymerization, and branching mediated by the anti-parallel dimer - Analytical Methods & Tools for Lyophilization

Actin crystal dynamics: structural implications for F-actin nucleation, polymerization, and branching mediated by the anti-parallel dimer
Received 9 September 2003; Revised 10 December 2003. Available online 14 January 2004.
Robbie Reutzela, 1, Craig Yoshiokaa, 1, 2, Lakshmanan Govindasamya, Elena G. Yarmolab, Mavis Agbandje-McKennaa, Michael R. Bubba, b and Robert McKenna, , a
Journal of Structural Biology
Volume 146, Issue 3 , June 2004
ScienceDirect
a Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610, USA
b The Research Service, Malcolm Randall Department of Veterans Affairs Medical Center and University of Florida College of Medicine, Gainesville, FL 32608, USA
Abstract
Actin filament nucleation, polymerization, and branching are crucial steps in many forms of cell motility, cell shape, and intracellular organelle movements in a wide range of organisms. Previous biochemical data suggests that an anti-parallel actin dimer can incorporate itself into growing filamentous actin (F-actin) and has a role in branching. Furthermore, it is a widespread belief that nucleation is spawned from an actin trimer complex. Here we present the structures of actin dimers and trimers in two tetragonal crystal systems P43212 and P43. Both crystal systems formed by an induced condensation transformation of a previously reported orthorhombic crystal system P212121. Comparison between the three crystal systems demonstrates the dynamics and flexibility of actin?actin interactions. The dimer and trimer actin rearrangements observed between the three crystal systems may provide insight to in vivo actin?actin interactions that occur during the nucleation, polymerization, and branching of F-actin.
Author Keywords: Actin; Polymerization; Nucleation; Branching; Dynamics

Corresponding author. Fax: 1-352-392-3422
1 These authors contributed equally to this work.
2 Present address: The Scripps Research Institute, La Jolla, CA 92037, USA.
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