Anaphase promoting complex-dependent degradation of transcriptional repressors Nrm1 and Yhp1 in Saccharomyces cerevisiae
Anaphase promoting complex-dependent degradation of transcriptional repressors Nrm1 and Yhp1 in Saccharomyces cerevisiae
复制标题
DOI：
10.1091/mbc.e11-01-0031
复制
发表时间：
2011-07-01
影响因子：
3.3
通讯作者：
Solomon, Mark J.
中科院分区：
文献类型：
--
作者：
Ostapenko, Denis;Solomon, Mark J.
后期促进复合物/环体（APC/C）是一种必需的泛素连接酶，靶向细胞周期蛋白，在有丝分裂和G1期进行蛋白酶体介导的降解。APC调节许多细胞周期过程，包括纺锤体组装、有丝分裂退出和胞质分裂，但其全部功能仍然未知。为了更好地理解由APC控制的细胞通路，我们进行了蛋白质组学筛选以鉴定另外的APC底物。我们分析了细胞周期调节蛋白，其表达在其他APC底物表达期间达到峰值。随后的分析确定了几种蛋白质，包括转录抑制因子Nrm 1和Yhp 1，作为真正的APC底物。我们发现APC（Cdh 1）通过Destruction box基序在G1早期靶向Nrm 1和Yhp 1降解，并且这些阻遏物的降解分别与MBF和Mcm 1靶基因的转录激活相一致。此外，Nrm 1是稳定的磷酸化，最有可能的芽殖酵母细胞周期蛋白依赖性蛋白激酶，Cdc 28。我们发现，Nrm 1和Yhp 1的稳定形式的表达导致细胞适应性降低，至少部分是由于G1特异性基因的不完全激活。因此，除了其已知的功能，APC介导的Nrm 1和Yhp 1靶向协调G1期多个基因的转录与其他细胞周期事件。
The anaphase-promoting complex/cyclosome (APC/C) is an essential ubiquitin ligase that targets cell cycle proteins for proteasome-mediated degradation in mitosis and G1. The APC regulates a number of cell cycle processes, including spindle assembly, mitotic exit, and cytokinesis, but the full range of its functions is still unknown. To better understand cellular pathways controlled by the APC, we performed a proteomic screen to identify additional APC substrates. We analyzed cell cycle-regulated proteins whose expression peaked during the period when other APC substrates were expressed. Subsequent analysis identified several proteins, including the transcriptional repressors Nrm1 and Yhp1, as authentic APC substrates. We found that APC(Cdh1) targeted Nrm1 and Yhp1 for degradation in early G1 through Destruction-box motifs and that the degradation of these repressors coincided with transcriptional activation of MBF and Mcm1 target genes, respectively. In addition, Nrm1 was stabilized by phosphorylation, most likely by the budding yeast cyclin-dependent protein kinase, Cdc28. We found that expression of stabilized forms of Nrm1 and Yhp1 resulted in reduced cell fitness, due at least in part to incomplete activation of G1-specific genes. Therefore, in addition to its known functions, APC-mediated targeting of Nrm1 and Yhp1 coordinates transcription of multiple genes in G1 with other cell cycle events.