Smt3/SUMO and Ubc9 are required for efficient APC/C-mediated proteolysis in budding yeast
Smt3/SUMO and Ubc9 are required for efficient APC/C-mediated proteolysis in budding yeast
复制标题
DOI：
10.1046/j.1365-2958.2003.03910.x
复制
发表时间：
2004-03-01
影响因子：
3.6
通讯作者：
Irniger, S
中科院分区：
文献类型：
--
作者：
Dieckhoff, P;Bolte, M;Irniger, S
由后期促进复合物/环体 (APC/C) 触发的泛素介导的蛋白水解对于姐妹染色单体分离和有丝分裂退出至关重要。与泛素化一样，用小型泛素相关修饰剂 SUMO 进行的蛋白质修饰似乎在有丝分裂过程中很重要，因为 SUMO 结合酶 Ubc9 受损的酵母细胞被发现在有丝分裂中受阻，并且细胞周期蛋白降解有缺陷。在这里，我们分析了 SUMO 化在酿酒酵母中期/后期转变和 APC/C 介导的蛋白水解中的作用。我们发现，耗尽 Ubc9 或 Smt3（酵母 SUMO 蛋白）的细胞大多被未分裂的细胞核和高水平的 securin Pds1 所捕获。 PDS1 的缺失部分缓解了中期阻滞。 Ubc9 或 Smt3 的缺失也会导致染色体分离缺陷。温度敏感的 ubc9-2 突变体在有丝分裂过程中 Pds1 和细胞周期蛋白 Clb2 的蛋白水解被延迟。在 G1 期停滞的细胞中更直接地测试了 APC/C 介导的降解的 SUMO 化要求。 ubc9-2 和 smt3-331 突变体在 Pds1 和有丝分裂细胞周期蛋白的有效降解方面均存在缺陷，而非 APC/C 底物的不稳定蛋白的蛋白水解不受影响。我们得出结论，芽殖酵母中 APC/C 介导的有效蛋白水解需要 SUMO 化。
Ubiquitin-mediated proteolysis triggered by the anaphase-promoting complex/cyclosome (APC/C) is essential for sister chromatid separation and the mitotic exit. Like ubiquitylation, protein modification with the small ubiquitin-related modifier SUMO appears to be important during mitosis, because yeast cells impaired in the SUMO-conjugating enzyme Ubc9 were found to be blocked in mitosis and defective in cyclin degradation. Here, we analysed the role of SUMOylation in the metaphase/anaphase transition and in APC/C-mediated proteolysis in Saccharomyces cerevisiae. We show that cells depleted of Ubc9 or Smt3, the yeast SUMO protein, mostly arrested with undivided nuclei and with high levels of securin Pds1. This metaphase block was partially relieved by a deletion of PDS1. The absence of Ubc9 or Smt3 also resulted in defects in chromosome segregation. Temperature-sensitive ubc9-2 mutants were delayed in proteolysis of Pds1 and of cyclin Clb2 during mitosis. The requirement of SUMOylation for APC/C-mediated degradation was tested more directly in G1-arrested cells. Both ubc9-2 and smt3-331 mutants were defective in efficient degradation of Pds1 and mitotic cyclins, whereas proteolysis of unstable proteins that are not APC/C substrates was unaffected. We conclude that SUMOylation is needed for efficient proteolysis mediated by APC/C in budding yeast.