title: Conformational changes in actin filaments induced by formin binding to the barbed end.
abstract: Formins bind actin filaments and play an essential role in the regulation of the actin cytoskeleton. In this work we describe details of the formin-induced conformational changes in actin filaments by fluorescence-lifetime and anisotropy-decay experiments. The results show that the binding of the formin homology 2 domain of a mammalian formin (mouse mDia1) to actin filaments resulted in a less rigid protein structure in the microenvironment of the Cys374 of actin, weakening of the interactions between neighboring actin protomers, and greater overall flexibility of the actin filaments. The formin effect is smaller at greater ionic strength. The results show that formin binding to the barbed end of actin filaments is responsible for the increase of flexibility of actin filaments. One formin dimer can affect the dynamic properties of an entire filament. Analyses of the results obtained at various formin/actin concentration ratios indicate that at least 160 actin protomers are affected by the binding of a single formin dimer to the barbed end of a filament.
authors.affiliation: Department of Biophysics, Faculty of Medicine, Office for Academy Research Groups, University of Pécs, Pécs, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Papp
authors.forename: Beáta
authors.initials: B
authors.lastname: Bugyi
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Ujfalusi
authors.forename: Szilvia
authors.initials: S
authors.lastname: Barkó
authors.forename: Gábor
authors.initials: G
authors.lastname: Hild
authors.forename: Béla
authors.initials: B
authors.lastname: Somogyi
authors.forename: Miklós
authors.initials: M
authors.lastname: Nyitrai
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry*; D000494:Allosteric Regulation; D002352:Carrier Proteins / Q000737:chemistry*; D019281:Dimerization; D005453:Fluorescence; D000080865:Formins; D008958:Models, Molecular; D009994:Osmolar Concentration; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D002352:Carrier Proteins; C491464:Diap1 protein, mouse; D000080865:Formins