Microtubule depolymerization can drive poleward chromosome motion in fission yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Kinetochores interact with spindle microtubules during prometaphase to ensure chromosome bi-orientation.
• Poleward movements (P-movements) of chromosomes are crucial for proper segregation and are often attributed to motor proteins.

Purpose of the Study:

• To investigate the factors driving poleward kinetochore movements in fission yeast.
• To determine the essentiality of specific motor proteins (dynein, Pkl1p, Klp2p) in mediating P-movements.

Main Methods:

• Analysis of kinetochore dynamics in fission yeast cells.
• Experimental dispersal of kinetochore-pole connections to induce recovery.
• Deletion analysis of motor protein genes (dynein, Pkl1p, Klp2p).

Main Results:

• The maximum rate of poleward kinetochore movement was not affected by the absence of any or all tested motor proteins.
• Microtubule depolymerization was identified as a significant factor contributing to P-movements in vivo.
• Klp2p, a kinetochore-localized kinesin, enhanced P-movement efficiency by promoting kinetochore fiber shortening.

Conclusions:

• Poleward kinetochore movements are not exclusively driven by known motor proteins in fission yeast.
• Microtubule dynamics, particularly depolymerization, play a critical role in chromosome movement during mitosis.
• Klp2p has a modulatory role in P-movement, distinct from its potential role as a primary driver.