title: Mechanical properties of organelles driven by microtubule-dependent molecular motors in living cells.
abstract: The organization of the cytoplasm is regulated by molecular motors which transport organelles and other cargoes along cytoskeleton tracks. Melanophores have pigment organelles or melanosomes that move along microtubules toward their minus and plus end by the action of cytoplasmic dynein and kinesin-2, respectively. In this work, we used single particle tracking to characterize the mechanical properties of motor-driven organelles during transport along microtubules. We tracked organelles with high temporal and spatial resolutions and characterized their dynamics perpendicular to the cytoskeleton track. The quantitative analysis of these data showed that the dynamics is due to a spring-like interaction between melanosomes and microtubules in a viscoelastic microenvironment. A model based on a generalized Langevin equation explained these observations and predicted that the stiffness measured for the motor complex acting as a linker between organelles and microtubules is ∼ one order smaller than that determined for motor proteins in vitro. This result suggests that other biomolecules involved in the interaction between motors and organelles contribute to the mechanical properties of the motor complex. We hypothesise that the high flexibility observed for the motor linker may be required to improve the efficiency of the transport driven by multiple copies of motor molecules.
authors.affiliation: Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1, Ciudad Universitaria, Ciudad de Buenos Aires, Argentina.
authors.forename: Luciana
authors.initials: L
authors.lastname: Bruno
authors.forename: Marcelo
authors.initials: M
authors.lastname: Salierno
authors.forename: Diana E
authors.initials: DE
authors.lastname: Wetzler
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Despósito
authors.forename: Valeria
authors.initials: V
authors.lastname: Levi
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002470:Cell Survival; D000072159:Dynactin Complex; D004548:Elasticity; D055595:Mechanical Phenomena; D020460:Melanosomes / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism*; D021381:Protein Transport; D014783:Viscosity; D014982:Xenopus laevis
chemical_list: D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins