title: A single charge in the actin binding domain of fascin can independently tune the linear and non-linear response of an actin bundle network.
abstract: Actin binding proteins (ABPs) not only set the structure of actin filament assemblies but also mediate the frequency-dependent viscoelastic moduli of cross-linked and bundled actin networks. Point mutations in the actin binding domain of those ABPs can tune the association and dissociation dynamics of the actin/ABP bond and thus modulate the network mechanics both in the linear and non-linear response regime. We here demonstrate how the exchange of a single charged amino acid in the actin binding domain of the ABP fascin triggers such a modulation of the network rheology. Whereas the overall structure of the bundle networks is conserved, the transition point from strain-hardening to strain-weakening sensitively depends on the cross-linker off-rate and the applied shear rate. Our experimental results are consistent both with numerical simulations of a cross-linked bundle network and a theoretical description of the bundle network mechanics which is based on non-affine bending deformations and force-dependent cross-link dynamics.
authors.affiliation: Lehrstuhl für Zellbiophysik E27, Physik-Department, Technische Universität München, Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Maier
authors.forename: K W
authors.initials: KW
authors.lastname: Müller
authors.forename: C
authors.initials: C
authors.lastname: Heussinger
authors.forename: S
authors.initials: S
authors.lastname: Köhler
authors.forename: W A
authors.initials: WA
authors.lastname: Wall
authors.forename: A R
authors.initials: AR
authors.lastname: Bausch
authors.forename: O
authors.initials: O
authors.lastname: Lieleg
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D011817:Rabbits; D055672:Static Electricity
chemical_list: D000199:Actins; D002352:Carrier Proteins; D008840:Microfilament Proteins; C020324:fascin