TY - JOUR T1 - Side-binding proteins modulate actin filament dynamics JF - bioRxiv DO - 10.1101/008128 SP - 008128 AU - Alvaro H. Crevenna AU - Marcelino Arciniega AU - Aurélie Dupont AU - Kaja Kowalska AU - Oliver F. Lange AU - Roland Wedlich-Söldner AU - Don C. Lamb Y1 - 2014/01/01 UR - http://biorxiv.org/content/early/2014/08/18/008128.abstract N2 - Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of the filament to polymerize and depolymerize at its ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. Here, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by proteins that bind to the lateral filament surface. We also show that the less dynamic end, called the pointed-end, has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of filament flexibility and Brownian dynamics simulations suggest that the observed kinetic diversity arises from structural alteration. Tuning filament kinetics by exploiting the natural malleability of the actin filament structure may be a ubiquitous mechanism to generate the rich variety of observed cellular actin dynamics. ER -