The Kinesin-8 Kip3 Depolymerizes Microtubules with a Collective Force-Dependent Mechanism.

The Kinesin-8 Kip3 Depolymerizes Microtubules with a Collective Force-Dependent Mechanism. Biophys J. 2020 Mar 14;: Authors: Bugiel M, Chugh M, Jachowski TJ, Schäffer E, Jannasch A Abstract Microtubules are highly dynamic filaments with dramatic structural rearrangements and length changes during the cell cycle. An accurate control of the microtubule length is essential for many cellular processes, in particular during cell division. Motor proteins from the kinesin-8 family depolymerize microtubules by interacting with their ends in a collective and length-dependent manner. However, it is still unclear how kinesin-8 depolymerizes microtubules. Here, we tracked the microtubule end-binding activity of yeast kinesin-8, Kip3, under varying loads and nucleotide conditions using high-precision optical tweezers. We found that single Kip3 motors spent up to 200 s at the microtubule end and were not stationary there but took several 8-nm forward and backward steps that were suppressed by loads. Interestingly, increased loads, similar to increased motor concentrations, also exponentially decreased the motors' residence time at the microtubule end. On the microtubule lattice, loads also exponentially decreased the run length and time. However, for the same load, lattice run times were significantly longer compared to end residence times, suggesting the presence of a distinct force-dependent detachment mechanism at the microtubule end. The for...
Source: Biophysical Journal - Category: Physics Authors: Tags: Biophys J Source Type: research