title: Small Crowders Slow Down Kinesin-1 Stepping by Hindering Motor Domain Diffusion.
abstract: The dimeric motor protein kinesin-1 moves processively along microtubules against forces of up to 7 pN. However, the mechanism of force generation is still debated. Here, we point to the crucial importance of diffusion of the tethered motor domain for the stepping of kinesin-1: small crowders stop the motor at a viscosity of 5 mPa·s-corresponding to a hydrodynamic load in the sub-fN (~10^{-4} pN) range-whereas large crowders have no impact even at viscosities above 100 mPa·s. This indicates that the scale-dependent, effective viscosity experienced by the tethered motor domain is a key factor determining kinesin's functionality. Our results emphasize the role of diffusion in the kinesin-1 stepping mechanism and the general importance of the viscosity scaling paradigm in nanomechanics.
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sozański
authors.affiliation: B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Ruhnow
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wiśniewska
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Tabaka
authors.affiliation: B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Diez
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Hołyst
mesh_terms: D004058:Diffusion; D016547:Kinesins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D014783:Viscosity
chemical_list: D016547:Kinesins