title: Broken Detailed Balance of Filament Dynamics in Active Networks.
abstract: Myosin motor proteins drive vigorous steady-state fluctuations in the actin cytoskeleton of cells. Endogenous embedded semiflexible filaments such as microtubules, or added filaments such as single-walled carbon nanotubes are used as novel tools to noninvasively track equilibrium and nonequilibrium fluctuations in such biopolymer networks. Here, we analytically calculate shape fluctuations of semiflexible probe filaments in a viscoelastic environment, driven out of equilibrium by motor activity. Transverse bending fluctuations of the probe filaments can be decomposed into dynamic normal modes. We find that these modes no longer evolve independently under nonequilibrium driving. This effective mode coupling results in nonzero circulatory currents in a conformational phase space, reflecting a violation of detailed balance. We present predictions for the characteristic frequencies associated with these currents and investigate how the temporal signatures of motor activity determine mode correlations, which we find to be consistent with recent experiments on microtubules embedded in cytoskeletal networks.
authors.affiliation: Third Institute of Physics, Georg August University, 37077 Göttingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Gladrow
authors.affiliation: Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.|Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.
authors.forename: N
authors.initials: N
authors.lastname: Fakhri
authors.affiliation: Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.|Department of Physics and Astronomy, Vrije Universiteit, 1081 HV Amsterdam, Netherlands.
authors.forename: F C
authors.initials: FC
authors.lastname: MacKintosh
authors.affiliation: Third Institute of Physics, Georg August University, 37077 Göttingen, Germany.|Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Schmidt
authors.affiliation: Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.|Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, D-80333 München, Germany.
authors.forename: C P
authors.initials: CP
authors.lastname: Broedersz
mesh_terms: D008841:Actin Cytoskeleton; D016547:Kinesins / Q000502:physiology*; D008870:Microtubules; D008968:Molecular Conformation; D009038:Motion; D037742:Nanotubes, Carbon
chemical_list: D037742:Nanotubes, Carbon; D016547:Kinesins