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Stu2 promotes mitotic spindle elongation in anaphase.

Severin F, Habermann B, Huffaker T, Hyman T - J. Cell Biol. (2001)

Bottom Line: We further show that the activity of Stu2 is opposed by the activity of the kinesin-related protein Kip3.Reexamination of the kinesin homology tree suggests that KIP3 is the S. cerevisiae orthologue of the microtubule-destabilizing subfamily of kinesins (Kin I).We conclude that a balance of activity between evolutionally conserved microtubule-stabilizing and microtubule-destabilizing factors is essential for correct spindle elongation during anaphase B.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse, 01307 Dresden, Germany.

ABSTRACT
During anaphase, mitotic spindles elongate up to five times their metaphase length. This process, known as anaphase B, is essential for correct segregation of chromosomes. Here, we examine the control of spindle length during anaphase in the budding yeast Saccharomyces cerevisiae. We show that microtubule stabilization during anaphase requires the microtubule-associated protein Stu2. We further show that the activity of Stu2 is opposed by the activity of the kinesin-related protein Kip3. Reexamination of the kinesin homology tree suggests that KIP3 is the S. cerevisiae orthologue of the microtubule-destabilizing subfamily of kinesins (Kin I). We conclude that a balance of activity between evolutionally conserved microtubule-stabilizing and microtubule-destabilizing factors is essential for correct spindle elongation during anaphase B.

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Real-time imaging of anaphase spindle elongation. (A) The kinetics of spindle elongation of five control and 10 stu2-10/kip3Δ/mad2Δ cells. (B) Anaphase video sequence of a stu2-10/kip3Δ/mad2Δ cell. Bar, 2 μm.
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Figure 6: Real-time imaging of anaphase spindle elongation. (A) The kinetics of spindle elongation of five control and 10 stu2-10/kip3Δ/mad2Δ cells. (B) Anaphase video sequence of a stu2-10/kip3Δ/mad2Δ cell. Bar, 2 μm.

Mentions: To compare the kinetics of spindle elongation in wild-type cells and stu2-10/kip3Δ/mad2Δ mutant, we introduced a GFP–tubulin construct into the cells and filmed spindle elongation in real time at 34°C. Fig. 6 A shows tracings of spindle elongation from wild-type and mutant cells. Fig. 6 B shows a typical mutant spindle elongating. Spindles from both wild-type and mutant cells show biphasic kinetics consistent with the data reported by Straight et al. 1997. The rates of spindle elongation between the wild-type and the mutant cells are similar at ∼0.6 and 0.14 μm/min. Therefore, we conclude that, indeed, spindles in the triple mutant elongate with similar kinetics to spindles in wild type.


Stu2 promotes mitotic spindle elongation in anaphase.

Severin F, Habermann B, Huffaker T, Hyman T - J. Cell Biol. (2001)

Real-time imaging of anaphase spindle elongation. (A) The kinetics of spindle elongation of five control and 10 stu2-10/kip3Δ/mad2Δ cells. (B) Anaphase video sequence of a stu2-10/kip3Δ/mad2Δ cell. Bar, 2 μm.
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Related In: Results  -  Collection

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Figure 6: Real-time imaging of anaphase spindle elongation. (A) The kinetics of spindle elongation of five control and 10 stu2-10/kip3Δ/mad2Δ cells. (B) Anaphase video sequence of a stu2-10/kip3Δ/mad2Δ cell. Bar, 2 μm.
Mentions: To compare the kinetics of spindle elongation in wild-type cells and stu2-10/kip3Δ/mad2Δ mutant, we introduced a GFP–tubulin construct into the cells and filmed spindle elongation in real time at 34°C. Fig. 6 A shows tracings of spindle elongation from wild-type and mutant cells. Fig. 6 B shows a typical mutant spindle elongating. Spindles from both wild-type and mutant cells show biphasic kinetics consistent with the data reported by Straight et al. 1997. The rates of spindle elongation between the wild-type and the mutant cells are similar at ∼0.6 and 0.14 μm/min. Therefore, we conclude that, indeed, spindles in the triple mutant elongate with similar kinetics to spindles in wild type.

Bottom Line: We further show that the activity of Stu2 is opposed by the activity of the kinesin-related protein Kip3.Reexamination of the kinesin homology tree suggests that KIP3 is the S. cerevisiae orthologue of the microtubule-destabilizing subfamily of kinesins (Kin I).We conclude that a balance of activity between evolutionally conserved microtubule-stabilizing and microtubule-destabilizing factors is essential for correct spindle elongation during anaphase B.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse, 01307 Dresden, Germany.

ABSTRACT
During anaphase, mitotic spindles elongate up to five times their metaphase length. This process, known as anaphase B, is essential for correct segregation of chromosomes. Here, we examine the control of spindle length during anaphase in the budding yeast Saccharomyces cerevisiae. We show that microtubule stabilization during anaphase requires the microtubule-associated protein Stu2. We further show that the activity of Stu2 is opposed by the activity of the kinesin-related protein Kip3. Reexamination of the kinesin homology tree suggests that KIP3 is the S. cerevisiae orthologue of the microtubule-destabilizing subfamily of kinesins (Kin I). We conclude that a balance of activity between evolutionally conserved microtubule-stabilizing and microtubule-destabilizing factors is essential for correct spindle elongation during anaphase B.

Show MeSH