title: Transition from a Linear to a Harmonic Potential in Collective Dynamics of a Multifilament Actin Bundle.
abstract: Attractive depletion forces between rodlike particles in highly crowded environments have been shown through recent modeling and experimental approaches to induce different structural and dynamic signatures depending on relative orientation between rods. For example, it has been demonstrated that the axial attraction between two parallel rods yields a linear energy potential corresponding to a constant contractile force of 0.1 pN. Here, we extend pairwise, depletion-induced interactions to a multifilament level with actin bundles, and find contractile forces up to 3 pN. Forces generated due to bundle relaxation were not constant, but displayed a harmonic potential and decayed exponentially with a mean decay time of 3.4 s. Through an analytical model, we explain these different fundamental dynamics as an emergent, collective phenomenon stemming from the additive, pairwise interactions of filaments within a bundle.
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Schnauß
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Golde
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schuldt
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: B U Sebastian
authors.initials: BU
authors.lastname: Schmidt
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Glaser
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Dan
authors.initials: D
authors.lastname: Strehle
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Händler
authors.affiliation: Institute for Theoretical Physics, Georg-August University of Göttingen, Friedrich-Hund Platz 1, 37077 Göttingen, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Heussinger
authors.affiliation: Institute of Experimental Physics I, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.
authors.forename: Josef A
authors.initials: JA
authors.lastname: Käs
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology*; D000199:Actins / Q000502:physiology*; D016014:Linear Models; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D052898:Optical Tweezers
chemical_list: D000199:Actins