Microtubule capture by mitotic kinesin centromere protein E (CENP-E)

Area of Science:

• Cell Biology
• Molecular Motors
• Kinesin Superfamily

Background:

• Centromere protein E (CENP-E) is a crucial kinetochore-associated kinesin-7 motor protein.
• CENP-E plays a vital role in establishing microtubule-chromosome linkages and chromosome congression to the spindle equator.

Purpose of the Study:

• To investigate the unique kinetic properties of CENP-E's interaction with microtubules.
• To elucidate the mechanism underlying CENP-E's processive movement and its role in chromosome alignment.

Main Methods:

• Kinetic analysis of CENP-E's microtubule association and dissociation rates.
• Measurement of ATP binding, hydrolysis, and ADP release.
• Determination of microtubule gliding velocity.

Main Results:

• CENP-E exhibits unusually slow microtubule association (0.08 μM⁻¹ s⁻¹) and ADP release (0.9 s⁻¹).
• ATP binding and hydrolysis are rapid, with motor dissociation occurring at 1.4 s⁻¹.
• Microtubule gliding velocity correlates with the dissociation rate, suggesting it limits the stepping rate.

Conclusions:

• CENP-E's slow microtubule association favors stable microtubules over dynamic ones.
• This kinetic preference biases CENP-E binding to kinetochore fibers, enhancing chromosome alignment accuracy.
• The rate-limiting step in CENP-E's processive run is likely head detachment, possibly controlled by phosphate release.