title: Myosin-Induced Gliding Patterns at Varied [MgATP] Unveil a Dynamic Actin Filament.
abstract: Actin filaments have key roles in cell motility but are generally claimed to be passive interaction partners in actin-myosin-based motion generation. Here, we present evidence against this static view based on an altered myosin-induced actin filament gliding pattern in an in vitro motility assay at varied [MgATP]. The statistics that characterize the degree of meandering of the actin filament paths suggest that for [MgATP] ≥ 0.25 mM, the flexural rigidity of heavy meromyosin (HMM)-propelled actin filaments is similar (without phalloidin) or slightly lower (with phalloidin) than that of HMM-free filaments observed in solution without surface tethering. When [MgATP] was reduced to ≤0.1 mM, the actin filament paths in the in vitro motility assay became appreciably more winding in both the presence and absence of phalloidin. This effect of lowered [MgATP] was qualitatively different from that seen when HMM was mixed with ATP-insensitive, N-ethylmaleimide-treated HMM (NEM-HMM; 25-30%). In particular, the addition of NEM-HMM increased a non-Gaussian tail in the path curvature distribution as well as the number of events in which different parts of an actin filament followed different paths. These effects were the opposite of those observed with reduced [MgATP]. Theoretical modeling suggests a 30-40% lowered flexural rigidity of the actin filaments at [MgATP] ≤ 0.1 mM and local bending of the filament front upon each myosin head attachment. Overall, the results fit with appreciable structural changes in the actin filament during actomyosin-based motion generation, and modulation of the actin filament mechanical properties by the dominating chemomechanical actomyosin state.
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Elina
authors.initials: E
authors.lastname: Bengtsson
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Persson
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Rahman
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Saroj
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Hideyo
authors.initials: H
authors.lastname: Takatsuki
authors.affiliation: Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden. Electronic address: alf.mansson@lnu.se.
authors.forename: Alf
authors.initials: A
authors.lastname: Månsson
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D004548:Elasticity; D008958:Models, Molecular; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism; D017711:Nonlinear Dynamics; D010590:Phalloidine / Q000737:chemistry; D011487:Protein Conformation; D012996:Solutions / Q000737:chemistry
chemical_list: D015879:Myosin Subfragments; D012996:Solutions; D010590:Phalloidine; D000255:Adenosine Triphosphate