Modeling processive motion of kinesin-13 MCAK and kinesin-14 Cik1-Kar3 molecular motors

Area of Science:

• Molecular motor dynamics
• Cellular mechanics
• Biophysics

Background:

• Kinesin motor proteins are crucial for intracellular transport along microtubules.
• Kinesin-13 MCAK (Microtubule Centromere-Associated protein) exhibits unbiased diffusion.
• Kinesin-14 Cik1-Kar3 moves processively towards microtubule minus ends.

Purpose of the Study:

• To develop and analyze models for the diffusion of MCAK homodimer and the processive motion of Cik1-Kar3 heterodimer.
• To investigate the underlying physical mechanisms governing the movement of these distinct kinesin dimers.
• To quantitatively compare theoretical predictions with existing experimental data.

Main Methods:

• Analytical modeling of kinesin dimer dynamics.
• Development of a diffusion model for MCAK homodimer.
• Development of a processive motion model for Cik1-Kar3 heterodimer.

Main Results:

• Theoretical models accurately reproduce experimental data for MCAK diffusion constants and microtubule-bound lifetimes.
• Models quantitatively predict Cik1-Kar3 velocity dependence on load and effects of motor homology domain alterations.
• The study proposes a conserved physical mechanism for processive motion in both kinesin dimers.

Conclusions:

• MCAK and Cik1-Kar3 dimers, despite structural differences, employ a similar physical mechanism for processive movement.
• The developed models provide a robust framework for understanding kinesin motor dynamics.
• Further predictions regarding motor dimer dynamics are offered for future experimental validation.