title: Formin and capping protein together embrace the actin filament in a ménage à trois.
abstract: Proteins targeting actin filament barbed ends play a pivotal role in motile processes. While formins enhance filament assembly, capping protein (CP) blocks polymerization. On their own, they both bind barbed ends with high affinity and very slow dissociation. Their barbed-end binding is thought to be mutually exclusive. CP has recently been shown to be present in filopodia and controls their morphology and dynamics. Here we explore how CP and formins may functionally coregulate filament barbed-end assembly. We show, using kinetic analysis of individual filaments by microfluidics-assisted fluorescence microscopy, that CP and mDia1 formin are able to simultaneously bind barbed ends. This is further confirmed using single-molecule imaging. Their mutually weakened binding enables rapid displacement of one by the other. We show that formin FMNL2 behaves similarly, thus suggesting that this is a general property of formins. Implications in filopodia regulation and barbed-end structural regulation are discussed.
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Shashank
authors.initials: S
authors.lastname: Shekhar
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Mikael
authors.initials: M
authors.lastname: Kerleau
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Sonja
authors.initials: S
authors.lastname: Kühn
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Pernier
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Romet-Lemonne
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Jégou
authors.affiliation: Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Carlier
mesh_terms: D051344:Actin Capping Proteins / Q000737:chemistry / Q000378:metabolism*; D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000080865:Formins; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits
chemical_list: D051344:Actin Capping Proteins; D048868:Adaptor Proteins, Signal Transducing; C108962:DIAPH1 protein, human; C476208:FMNL2 protein, human; D000080865:Formins; D011506:Proteins