Kinesin-5 is a microtubule polymerase

Area of Science:

• Cell Biology
• Molecular Motors
• Biophysics

Background:

• Kinesin-5 motors are crucial for microtubule dynamics during cell division and axon growth.
• The precise motor properties of Kinesin-5 that govern its cellular functions are not fully understood.

Purpose of the Study:

• To elucidate the specific motor properties of Kinesin-5 that regulate microtubule polymerization.
• To investigate how Kinesin-5 influences microtubule dynamics at the plus end.

Main Methods:

• Engineering a stable Kinesin-5 dimer for in vitro studies.
• Reconstituting microtubule polymerization dynamics in vitro.
• Utilizing single-molecule fluorescence experiments to track Kinesin-5 behavior.

Main Results:

• Kinesin-5 significantly increases microtubule polymerization growth rates and decreases catastrophe frequency.
• Microtubules growing with Kinesin-5 exhibit curved plus ends, indicating stabilization of protofilaments.
• Kinesin-5 exhibits prolonged binding to static microtubule plus ends and tracks growing ends based on processivity.

Conclusions:

• Kinesin-5 promotes microtubule polymerization by stabilizing protofilament interactions at the plus end.
• These polymerization-enhancing activities contribute to Kinesin-5's known roles in sliding and stabilizing microtubule bundles.