Modular aspects of kinesin force generation machinery

Area of Science:

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

Background:

• Kinesin motor proteins are crucial for intracellular transport, walking along microtubules.
• Kinesin-1 (Kin-1) and Kinesin-5 (Kin-5) exhibit distinct motility despite conserved motor heads.
• Subtle subdomain variations dictate family-specific kinesin properties and functions.

Purpose of the Study:

• To investigate the structural and mechanical basis for distinct motility characteristics between Kinesin-1 and Kinesin-5.
• To determine if Kinesin-5 utilizes a similar force-generating element as Kinesin-1.
• To elucidate how subdomain variations contribute to functional diversity in conserved kinesin motor heads.

Main Methods:

• Utilized single-molecule motility assays to analyze kinesin behavior.
• Employed molecular dynamics simulations to study motor head mechanics.
• Constructed and analyzed chimeric Kinesin-1/Kinesin-5 motor proteins.

Main Results:

• Kinesin-5 shares a force-generating element, the cover-neck bundle, with Kinesin-1.
• Kinesin-5's neck linker forms additional contacts with the motor head core via loop L13.
• Kinesin-1 is optimized for individual cargo transport; Kinesin-5 is suited for group operation.

Conclusions:

• Kinesin-5's unique neck linker interactions compensate for its shorter cover-neck bundle.
• Kinesin-5's mechanical properties and force sensitivity favor collective motor action.
• Subdomain variations within conserved motor heads are a key strategy for kinesin functional diversity.