Microtubule depolymerization by the Kinesin-8 motor Kip3p: a mathematical model.
Proteins from the kinesin-8 family promote microtubule (MT) depolymerization, a process thought to be important for the control of microtubule length in living cells. In addition to this MT shortening activity, kinesin 8s are motors that show plus-end directed motility on MTs. Here we describe a simple model that incorporates directional motion and destabilization of the MT plus-end by kinesin 8. Our model quantitatively reproduces the key features of length-versus-time traces for stabilized MTs in the presence of purified kinesin 8, including length-dependent depolymerization. Comparison of model predictions with experiments suggests that kinesin 8 depolymerizes processively, i.e., one motor can remove multiple tubulin dimers from a stabilized MT. Fluctuations in MT length as a function of time are related to depolymerization processivity. We have also determined the parameter regime in which the rate of MT depolymerization is length dependent: length-dependent depolymerization occurs only when MTs are sufficiently short; this crossover is sensitive to the bulk motor concentration.
Hough
L E
LE
Physics Department, University of Colorado at Boulder, Boulder, Colorado, USA.
Schwabe
Anne
A
Glaser
Matthew A
MA
McIntosh
J Richard
JR
Betterton
M D
MD
D000465:Algorithms; D003198:Computer Simulation; D016547:Kinesins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D008954:Models, Biological; D009010:Monte Carlo Method; D055550:Protein Stability
D016547:Kinesins