期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 381, 期 3, 页码 550-558出版社
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2008.05.055
关键词
single molecule; imaging; biopolymer mechanics; persistence length; severing
资金
- American Heart Association [0655849T]
- National Science Foundation [MCB-0546353]
- National Institutes of Health [GM071688, T32GM007223]
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 mu m, corresponding to a flexural rigidity of 0.040 pN mu m(2). Cofilin binding lowers the persistence length similar to 5-fold to a value of 2.2 mu m and the filament flexural rigidity to 0.0091 pN mu m(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. (C) 2008 Elsevier Ltd. All rights reserved.
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