Membrane mediated motor kinetics in microtubule gliding assays

Sci Rep. 2019 Jul 3;9(1):9584. doi: 10.1038/s41598-019-45847-z.

Abstract

Motor-based transport mechanisms are critical for a wide range of eukaryotic cell functions, including the transport of vesicle cargos over long distances. Our understanding of the factors that control and regulate motors when bound to a lipid substrate is however incomplete. We used microtubule gliding assays on a lipid bilayer substrate to investigate the role of membrane diffusion in kinesin-1 on/off binding kinetics and thereby transport velocity. Fluorescence imaging experiments demonstrate motor clustering on single microtubules due to membrane diffusion in the absence of ATP, followed by rapid ATP-induced dissociation during gliding. Our experimental data combined with analytical modeling show that the on/off binding kinetics of the motors are impacted by diffusion and, as a consequence, both the effective binding and unbinding rates for motors are much lower than the expected bare rates. Our results suggest that motor diffusion in the membrane can play a significant role in transport by impacting motor kinetics and can therefore function as a regulator of intracellular transport dynamics.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Diffusion
  • Fluorescence Recovery After Photobleaching
  • Image Processing, Computer-Assisted
  • Kinesins / chemistry
  • Kinesins / metabolism
  • Kinetics
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism*
  • Microscopy, Fluorescence
  • Microtubules / chemistry
  • Microtubules / metabolism*
  • Protein Binding
  • Swine

Substances

  • Lipid Bilayers
  • Adenosine Triphosphate
  • Kinesins