Modulation of formin processivity by profilin and mechanical tension

• Main Authors: Luyan Cao, Mikael Kerleau, Emiko L. Suzuki, Hugo Wioland, Sandy Jouet, Berengere Guichard, Martin Lenz, Guillaume Romet-Lemonne, Antoine Jegou
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2018-05-01
• Series: eLife
• Subjects: actin; cytoskeleton; microfluidics; mechanotransduction; formin; profilin
• Online Access: https://elifesciences.org/articles/34176

Formins are major regulators of actin networks. They enhance actin filament dynamics by remaining processively bound to filament barbed ends. How biochemical and mechanical factors affect formin processivity are open questions. Monitoring individual actin filaments in a microfluidic flow, we report that formins mDia1 and mDia2 dissociate faster under higher ionic strength and when actin concentration is increased. Profilin, known to increase the elongation rate of formin-associated filaments, surprisingly decreases the formin dissociation rate, by bringing formin FH1 domains in transient contact with the barbed end. In contrast, piconewton tensile forces applied to actin filaments accelerate formin dissociation by orders of magnitude, largely overcoming profilin-mediated stabilization. We developed a model of formin conformations showing that our data indicates the existence of two different dissociation pathways, with force favoring one over the other. How cells limit formin dissociation under tension is now a key question for future studies.