Centromere protein F includes two sites that couple efficiently to depolymerizing microtubules

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Accurate chromosome segregation relies on stable kinetochore-microtubule attachments during mitosis.
• Centromere protein F (CENP-F) possesses microtubule-binding domains, suggesting a role in kinetochore-microtubule interactions.

Purpose of the Study:

• To investigate the microtubule-binding properties of CENP-F.
• To determine CENP-F's contribution to kinetochore-microtubule attachments and force generation.

Main Methods:

• Utilized in vitro assays to assess the binding preference of CENP-F's N-terminal domain for tubulin oligomers versus microtubule walls.
• Examined the dynamics of CENP-F fragments on stable and dynamic microtubules.
• Measured the force transduced by CENP-F fragments from shortening microtubules using microbead assays.

Main Results:

• The N-terminal MT-binding domain of CENP-F showed a fivefold preference for curled tubulin oligomers over microtubule walls.
• Both N-terminal and C-terminal CENP-F fragments bound to microtubules and tracked their shortening dynamics.
• CENP-F fragments coupled to microbeads generated forces of 3-5 pN, with peaks exceeding 10 pN, from shortening microtubules.

Conclusions:

• CENP-F's preferential binding to tubulin structures at microtubule plus ends likely stabilizes kinetochore attachments.
• CENP-F functions as a potent coupler, effectively transducing force from dynamic, shortening microtubules during mitosis.