Budding yeast mitotic chromosomes have an intrinsic bias to biorient on the spindle
Budding yeast mitotic chromosomes have an intrinsic bias to biorient on the spindle
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DOI：
10.1016/j.cub.2007.09.056
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发表时间：
2007-11-06
期刊：
影响因子：
9.2
通讯作者：
Murray, Andrew W.
中科院分区：
文献类型：
--
作者：
Indjeian, Vahan B.;Murray, Andrew W.
背景：染色体必须在有丝分裂纺锤体上生物定向，姐妹俩附着在相反的纺锤体极上。纺锤体检查点检测未连接的染色体，并通过检测连接到同一极点的两姐妹之间是否缺乏张力来监测双向定位。结果：在sgo1突变体中，染色体正常附着在微管上，但如果姐妹染色体附着在同一极上，则染色体不能重新定位。当染色体附着在微管上时，突变体的命运取决于纺锤体极的位置。如果两极分离，姐妹染色单体生物定向，但如果两极仍然很近，姐妹染色单体往往附着在同一极，错误分离，并导致细胞死亡。结论：这些观察结果表明，发芽酵母有丝分裂染色体对纺锤体上的生物定向具有内在的几何偏向。当两极已经分离时，将一个着丝粒附着在一个极上，就会使它的姐妹染色体附着在另一极上，从而使细胞能够正确地分离染色体。当极点没有分离时，第二个动粒最终随机附着在两个极点中的任何一个上，导致方向误差在野生型中得到纠正，但在sgo1突变体中没有得到纠正。在没有纺锤体损伤的情况下，sgo1细胞成功分裂，这表明动点只有在细胞进入有丝分裂并分离纺锤体极后才能稳定地附着在微管上。
Background: Chromosomes must biorient on the mitotic spindle, with the two sisters attached to opposite spindle poles. The spindle checkpoint detects unattached chromosomes and monitors biorientation by detecting the lack of tension between two sisters attached to the same pole. After the spindle has been depolymerized and allowed to reform, budding yeast sgo1 mutants fail to biorient their sister chromatids and die as cells divide.Results: In sgo1 mutants, chromosomes attach to microtubules normally but cannot reorient if both sisters attach to the same pole. The mutants' fate depends on the position of the spindle poles when the chromosomes attach to microtubules. If the poles have separated, sister chromatids biorient, but if the poles are still close, sister chromatids often attach to the same pole, missegregate, and cause cell death.Conclusions: These observations argue that budding yeast mitotic chromosomes have an intrinsic, geometric bias to biorient on the spindle. When the poles have already separated, attaching one kinetochore to one pole predisposes its sister to attach to the opposite pole, allowing the cells to segregate the chromosomes correctly. When the poles have not separated, the second kinetochore eventually attaches to either of the two poles randomly, causing orientation errors that are corrected in the wild-type but not in sgo1 mutants. In the absence of spindle damage, sgo1 cells divide successfully, suggesting that kinetochores only make stable attachments to microtubules after the cells have entered mitosis and separated their spindle poles.