AI Article Synopsis
- In fission yeast, while Gfh1, Mod21, and Alp16 are nonessential for growth, the deletion of Alp16 results in synthetic lethality with certain Mzt1 mutants, indicating its specific importance in γ-tubulin ring complex recruitment.
- Alp16 deletion leads to reduced γ-tubulin levels at spindle pole bodies and causes issues like monopolar spindle formation and minichromosome loss when spindle checkpoints are disrupted, highlighting its role in microtubule assembly.
- The study suggests that Alp16 and Mzt1 work together to promote effective spindle assembly and chromosome segregation, with Mzt1's levels being critical for this process.
Article Abstract
In fission yeast, γ-tubulin ring complex (γTuRC)-specific components Gfh1(GCP4), Mod21(GCP5), and Alp16(GCP6) are nonessential for cell growth. Of these deletion mutants, only alp16Δ shows synthetic lethality with temperature-sensitive mutants of Mzt1(MOZART1), a component of the γTuRC required for recruitment of the complex to microtubule-organizing centers. γ-Tubulin small complex levels at mitotic spindle pole bodies (SPBs, the centrosome equivalent in fungi) and microtubule levels for preanaphase spindles are significantly reduced in alp16Δ cells but not in gfh1Δ or mod21Δ cells. Furthermore, alp16Δ cells often form monopolar spindles and frequently lose a minichromosome when the spindle assembly checkpoint is inactivated. Alp16(GCP6) promotes Mzt1-dependent γTuRC recruitment to mitotic SPBs and enhances spindle microtubule assembly in a manner dependent on its expression levels. Gfh1(GCP4) and Mod21(GCP5) are not required for Alp16(GCP6)-dependent γTuRC recruitment. Mzt1 has an additional role in the activation of the γTuRC for spindle microtubule assembly. The ratio of Mzt1 to γTuRC levels for preanaphase spindles is higher than at other stages of the cell cycle. Mzt1 overproduction enhances spindle microtubule assembly without affecting γTuRC levels at mitotic SPBs. We propose that Alp16(GCP6) and Mzt1 act synergistically for efficient bipolar spindle assembly to ensure faithful chromosome segregation.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884066 | PMC |
| http://dx.doi.org/10.1091/mbc.E15-08-0577 | DOI Listing |
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