Related Experiment Video
Updated: Jul 19, 2026
Examination of Mitotic and Meiotic Fission Yeast Nuclear Dynamics by Fluorescence Live-cell Microscopy
Published on: June 24, 2019
Microtubule depolymerization can drive poleward chromosome motion in fission yeast
Ekaterina L Grishchuk1, J Richard McIntosh
1MCD Biology Department, University of Colorado at Boulder, Boulder, CO 80309, USA. katya@colorado.edu
Abstract:
Prometaphase kinetochores interact with spindle microtubules (MTs) to establish chromosome bi-orientation. Before becoming bi-oriented, chromosomes frequently exhibit poleward movements (P-movements), which are commonly attributed to minus end-directed, MT-dependent motors. In fission yeast there are three such motors: dynein and two kinesin-14s, Pkl1p and Klp2p. None of these enzymes is essential for viability, and even the triple deletion grows well. This might be due to the fact that yeasts kinetochores are normally juxtapolar at mitosis onset, removing the need for poleward chromosome movement during prometaphase. Anaphase P-movement might also be dispensable in a spindle that elongates significantly. To test this supposition, we have analyzed kinetochore dynamics in cells whose kinetochore-pole connections have been dispersed. In cells recovering from this condition, the maximum rate of poleward kinetochore movement was unaffected by the deletion of any or all of these motors, strongly suggesting that other factors, like MT depolymerization, can cause such movements in vivo. However, Klp2p, which localizes to kinetochores, contributed to the effectiveness of P-movement by promoting the shortening of kinetochore fibers.
Insights
Poleward chromosome movements in fission yeast are not solely dependent on motor proteins. Microtubule depolymerization also drives these essential movements during cell division.
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.
Related Concept Videos
02:11Forces Acting on Chromosomes
Microtubules and motor proteins exert two types of forces on...
01:39Anaphase A and B
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...
01:45Destabilization of Microtubules
02:50Spindle Assembly
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
02:17Microtubule Instability
02:17Microtubule Instability