Working strokes by single molecules of the kinesin-related microtubule motor ncd.
The ncd protein is a dimeric, ATP-powered motor that belongs to the kinesin family of microtubule motor proteins. Here we resolve single mechanochemical cycles of recombinant, dimeric, full-length ncd, using optical-tweezers-based instrumentation and a three-bead, suspended-microtubule assay. Under conditions of limiting ATP, isolated and transient microtubule-binding events exhibit exponentially distributed and ATP-concentration-dependent lifetimes. These events do not involve consecutive steps along the microtubule, quantitatively confirming that ncd is non-processive. At low loads, a single motor molecule produces ATP-triggered working strokes of about 9 nm, which occur at the ends of binding events.
deCastro
M J
MJ
Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA.
Fondecave
R M
RM
Clarke
L A
LA
Schmidt
C F
CF
Stewart
R J
RJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D001696:Biomechanical Phenomena; D029721:Drosophila Proteins; D016547:Kinesins / Q000502:physiology*; D008870:Microtubules / Q000502:physiology*; D008962:Models, Theoretical; D020409:Molecular Motor Proteins / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D055095:Optics and Photonics
D029721:Drosophila Proteins; D020409:Molecular Motor Proteins; C066696:ncd protein, Drosophila; D000255:Adenosine Triphosphate; D016547:Kinesins