Examining kinesin processivity within a general gating framework.

Area of Science:

• Molecular motor function
• Cellular transport mechanisms
• Biophysics of protein dynamics

Background:

• Kinesin-1 is a dimeric motor protein essential for intracellular transport along microtubules.
• It moves via a hand-over-hand mechanism, with coordinated ATP hydrolysis cycles in its two heads.
• The neck linker (NL) is a critical structural component for inter-head coordination.

Purpose of the Study:

• To investigate the role of the neck linker (NL) length in regulating kinesin-1 stepping and processivity.
• To determine the contribution of inter-head tension to motor coordination and function.
• To elucidate the gating mechanisms governing kinesin-1's hand-over-hand movement.

Main Methods:

• Single-molecule optical trapping assays to measure motor force and velocity.
• Bulk fluorescence approaches to analyze protein conformational changes.
• Investigation of various neck linker mutants with altered lengths.

Main Results:

• Inter-head tension enhances kinesin-1 motor velocity but is not essential for coordination or rear-head release.
• Altered neck linker lengths and cysteine-light mutations affect wild-type motility under load.
• Kinesin-1 primarily operates via front-head gating.

Conclusions:

• Neck linker length is fine-tuned to optimize kinesin-1's unidirectional processivity and velocity.
• The motor's function is predominantly controlled by the front head's gating mechanism.
• Inter-head tension plays a secondary role in kinesin-1's coordinated movement.