Yamamoto A, Guacci V, Koshland D
Carnegie Institution of Washington, Department of Embryology, Baltimore, Maryland 21210, USA.
J Cell Biol. 1996 Apr;133(1):99-110. doi: 10.1083/jcb.133.1.99.
We report the isolation and characterization of pds1 mutants in Saccharomyces cerevisiae. The initial pds1-1 allele was identified by its inviability after transient exposure to microtubule inhibitors and its precocious dissociation of sister chromatids in the presence of these microtubule inhibitors. These findings suggest that pds1 mutants might be defective in anaphase arrest that normally is imposed by a spindle-damage checkpoint. To further examine a role for Pds1p in anaphase arrest, we compared the cell cycle arrest of pds1 mutants and PDS1 cells after: (a) the inactivation of Cdc16p or Cdc23p, two proteins that are required for the degradation of mitotic cyclins and are putative components of the yeast anaphase promoting complex (APC); (b) the inactivation of Cdc20p, another protein implicated in the degradation of mitotic cyclins; and (c) the inactivation of Cdc13 protein or gamma irradiation, two circumstances that induce a DNA-damage checkpoint. Under all these conditions, anaphase is inhibited in PDS1 cells but not in pds1 mutants. From these results we suggest that Pds1 protein is an anaphase inhibitor in PDS1 cells but not in pds1 mutants. From these results we suggest that Pds1 protein is an anaphase inhibitor that plays a critical role in the control of anaphase by both APC and checkpoints. We also show that pds1 mutants exit mitosis and initiate new rounds of cell division after gamma irradiation and Cdc13p inactivation but no after nocodazole-treatment or inactivation of Cdc16p, Cdc20p or Cdc23p function. Therefore, in the DNA-damage checkpoint, Pds1p is required for the inhibition of cytokinesis and DNA replication as well as anaphase. The role of Pds1 protein in anaphase inhibition and general cell cycle regulation is discussed.
我们报告了酿酒酵母中pds1突变体的分离和特性分析。最初的pds1-1等位基因是通过其在短暂暴露于微管抑制剂后无法存活以及在这些微管抑制剂存在下姐妹染色单体过早解离而鉴定出来的。这些发现表明，pds1突变体可能在通常由纺锤体损伤检查点施加的后期停滞中存在缺陷。为了进一步研究Pds1p在后期停滞中的作用，我们比较了pds1突变体和PDS1细胞在以下情况后的细胞周期停滞：(a)Cdc16p或Cdc23p失活，这两种蛋白质是有丝分裂周期蛋白降解所必需的，并且是酵母后期促进复合物(APC)的假定成分；(b)Cdc20p失活，另一种与有丝分裂周期蛋白降解有关的蛋白质；(c)Cdc13蛋白失活或γ射线照射，这两种情况会诱导DNA损伤检查点。在所有这些条件下，PDS1细胞中的后期受到抑制，而pds1突变体中则不受抑制。从这些结果我们认为，Pds1蛋白在PDS1细胞中是后期抑制剂，但在pds1突变体中不是。从这些结果我们认为，Pds1蛋白是一种后期抑制剂，在APC和检查点对后期的控制中起关键作用。我们还表明，pds1突变体在γ射线照射和Cdc?13p失活后退出有丝分裂并开始新一轮细胞分裂，但在诺考达唑处理或Cdc16p、Cdc20p或Cdc23p功能失活后则不会。因此，在DNA损伤检查点中，Pds1p是抑制胞质分裂和DNA复制以及后期所必需的。讨论了Pds1蛋白在后期抑制和一般细胞周期调控中的作用。
