title: Side-binding proteins modulate actin filament dynamics.
abstract: Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of filaments to polymerize and depolymerize at their ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. In this study, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by the binding of proteins to the lateral filament surface. We also show that the pointed-end has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of flexibility as well as effects on fragmentation and growth suggest that the observed kinetic diversity arises from structural alteration. Tuning elongation kinetics by exploiting the malleability of the filament structure may be a ubiquitous mechanism to generate a rich variety of cellular actin dynamics.
authors.affiliation: Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.|Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany.
authors.forename: Alvaro H
authors.identifier: http://orcid.org/0000-0002-5580-3711
authors.initials: AH
authors.lastname: Crevenna
authors.affiliation: Max Planck Institute of Biochemistry, Martinsried, Germany.|Department of Chemistry, Technische Universität München, Garching, Germany.
authors.forename: Marcelino
authors.initials: M
authors.lastname: Arciniega
authors.affiliation: Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.|NanoSystems Initiative Munich, Ludwig-Maximilians-Universität München, Munich, Germany.|Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Dupont
authors.affiliation: Cellular and Membrane Trafficking, Max Planck Institute of Biochemistry, Martinsried, Germany.
authors.forename: Naoko
authors.initials: N
authors.lastname: Mizuno
authors.affiliation: Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany.
authors.forename: Kaja
authors.initials: K
authors.lastname: Kowalska
authors.affiliation: Department of Chemistry, Technische Universität München, Garching, Germany.|Biomolecular NMR and Munich Center for Integrated Protein Science, Technische Universität München, Garching, Germany.|Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Oliver F
authors.initials: OF
authors.lastname: Lange
authors.affiliation: Cellular Dynamics and Cell Patterning, Max Planck Institute of Biochemistry, Martinsried, Germany.|Institute of Cell Dynamics and Imaging, Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Münster, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Wedlich-Söldner
authors.affiliation: Physical Chemistry, Department of Chemistry and Center for Nanoscience, Ludwig-Maximilians-Universität München, Munich, Germany.|NanoSystems Initiative Munich, Ludwig-Maximilians-Universität München, Munich, Germany.|Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: Don C
authors.initials: DC
authors.lastname: Lamb
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000465:Algorithms; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002645:Chickens; D064448:Filamins / Q000378:metabolism; D007700:Kinetics; D008840:Microfilament Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence / Q000379:methods*; D008954:Models, Biological; D009010:Monte Carlo Method; D009218:Myosins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D058105:Polymerization; D011485:Protein Binding; D061987:Sf9 Cells; D018411:Spodoptera
chemical_list: D000199:Actins; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D064448:Filamins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D000185:Actinin; D000255:Adenosine Triphosphate; D009218:Myosins
keywords: TIRF; actin; actin-binding proteins; biophysics; cell biology; structural biology; treadmilling