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Cofilin increases the bending flexibility of actin filaments: implications for severing and cell mechanics.

Brannon Mccullough 1 Laurent Blanchoin 2 Jean-Louis Martiel 3 Enrique de la Cruz 1
3 TIMB
TIMC - Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications, Grenoble - UMR 5525, Ingénierie pour le vivant
Abstract : We determined the flexural (bending) rigidities of actin and cofilactin filaments from a cosine correlation function analysis of their thermally driven, two-dimensional fluctuations in shape. The persistence length of actin filaments is 9.8 microm, corresponding to a flexural rigidity of 0.040 pN microm(2). Cofilin binding lowers the persistence length approximately 5-fold to a value of 2.2 microm and the filament flexural rigidity to 0.0091 pN microm(2). That cofilin-decorated filaments are more flexible than native filaments despite an increased mass indicates that cofilin binding weakens and redistributes stabilizing subunit interactions of filaments. We favor a mechanism in which the increased flexibility of cofilin-decorated filaments results from the linked dissociation of filament-stabilizing ions and reorganization of actin subdomain 2 and as a consequence promotes severing due to a mechanical asymmetry. Knowledge of the effects of cofilin on actin filament bending mechanics, together with our previous analysis of torsional stiffness, provide a quantitative measure of the mechanical changes in actin filaments associated with cofilin binding, and suggest that the overall mechanical and force-producing properties of cells can be modulated by cofilin activity.
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https://www.hal.inserm.fr/inserm-00338171
Contributor : Jean-Louis Martiel <>
Submitted on : Tuesday, November 11, 2008 - 6:46:00 PM
Last modification on : Thursday, November 19, 2020 - 3:56:08 PM

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Brannon Mccullough, Laurent Blanchoin, Jean-Louis Martiel, Enrique de la Cruz. Cofilin increases the bending flexibility of actin filaments: implications for severing and cell mechanics.. Journal of Molecular Biology, Elsevier, 2008, 381 (3), pp.550-8. ⟨10.1016/j.jmb.2008.05.055⟩. ⟨inserm-00338171⟩

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