Coupling of two non-processive myosin 5c dimers enables processive stepping along actin filaments

Sci Rep. 2014 May 9;4:4907. doi: 10.1038/srep04907.

Abstract

Myosin 5c (Myo5c) is a low duty ratio, non-processive motor unable to move continuously along actin filaments though it is believed to participate in secretory vesicle trafficking in vertebrate cells. Here, we measured the ATPase kinetics of Myo5c dimers and tested the possibility that the coupling of two Myo5c molecules enables processive movement. Steady-state ATPase activity and ADP dissociation kinetics demonstrated that a dimer of Myo5c-HMM (double-headed heavy meromyosin 5c) has a 6-fold lower Km for actin filaments than Myo5c-S1 (single-headed myosin 5c subfragment-1), indicating that the two heads of Myo5c-HMM increase F-actin-binding affinity. Nanometer-precision tracking analyses showed that two Myo5c-HMM dimers linked with each other via a DNA scaffold and moved processively along actin filaments. Moreover, the distance between the Myo5c molecules on the DNA scaffold is an important factor for the processive movement. Individual Myo5c molecules in two-dimer complexes move stochastically in 30-36 nm steps. These results demonstrate that two dimers of Myo5c molecules on a DNA scaffold increased the probability of rebinding to F-actin and enabled processive steps along actin filaments, which could be used for collective cargo transport in cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphatases
  • DNA / metabolism
  • Enzyme Activation
  • Gene Expression
  • Humans
  • Hydrolysis
  • Kinetics
  • Myosin Type V / chemistry
  • Myosin Type V / genetics
  • Myosin Type V / metabolism*
  • Protein Binding
  • Protein Multimerization*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • Recombinant Proteins
  • Adenosine Diphosphate
  • DNA
  • Adenosine Triphosphatases
  • Myosin Type V