Tether-scanning the kinesin motor domain reveals a core mechanical action

Area of Science:

• Biophysics
• Molecular Biology
• Cellular Mechanics

Background:

• Kinesin motors generate directional force through linker docking against the motor domain.
• The precise contribution of linker docking to the fundamental force-generating cycle of kinesin remains unclear.

Purpose of the Study:

• To investigate whether kinesin motor domains possess an intrinsic force-generating mechanism separate from linker docking.
• To determine if linker docking amplifies an underlying force-generating cycle.

Main Methods:

• Kinesin motor domains were tethered using double-stranded DNA (dsDNA) attached to surface loops.
• Microtubule (MT) gliding assays were used to observe motility.
• Attachment positions of dsDNA tethers were varied on surface loops (loop 2 and loop 10).

Main Results:

• Kinesin motor domains tethered via dsDNA on surface loops drove robust MT gliding.
• Disconnecting the C-terminal neck-linker and N-terminal cover strand via dsDNA tethering did not abolish force generation.
• Effective tethering at loop 2 and loop 10 positions, near MT ends, supported motility.
• Minus-end-directed motility was observed in three instances.

Conclusions:

• Kinesin motor domains exhibit an inherent, fundamental force-generating mechanical action.
• This core mechanical action is amplified by the linker docking process.
• The findings suggest an ancient, conserved force-generating mechanism within kinesin motors.