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Tension modulates actin filament polymerization mediated by formin and profilin.

ABSTRACT: Formins promote processive elongation of actin filaments for cytokinetic contractile rings and other cellular structures. In vivo, these structures are exposed to tension, but the effect of tension on these processes was unknown. Here we used single-molecule imaging to investigate the effects of tension on actin polymerization mediated by yeast formin Bni1p. Small forces on the filaments dramatically slowed formin-mediated polymerization in the absence of profilin, but resulted in faster polymerization in the presence of profilin. We propose that force shifts the conformational equilibrium of the end of a filament associated with formin homology 2 domains toward the closed state that precludes polymerization, but that profilin-actin associated with formin homology 1 domains reverses this effect. Thus, physical forces strongly influence actin assembly by formin Bni1p.

SUBMITTER: Courtemanche N

PROVIDER: S-EPMC3683744 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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Tension modulates actin filament polymerization mediated by formin and profilin.

Courtemanche Naomi N Lee Ja Yil JY Pollard Thomas D TD Greene Eric C EC

Proceedings of the National Academy of Sciences of the United States of America 20130528 24

Formins promote processive elongation of actin filaments for cytokinetic contractile rings and other cellular structures. In vivo, these structures are exposed to tension, but the effect of tension on these processes was unknown. Here we used single-molecule imaging to investigate the effects of tension on actin polymerization mediated by yeast formin Bni1p. Small forces on the filaments dramatically slowed formin-mediated polymerization in the absence of profilin, but resulted in faster polymer ...[more]

PMID: 23716666

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