Remodeling of the SCF complex-mediated ubiquitination system by compositional alteration of incorporated F-box proteins
Remodeling of the SCF complex-mediated ubiquitination system by compositional alteration of incorporated F-box proteins
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DOI：
10.1002/pmic.200900497
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发表时间：
2010-01-01
期刊：
影响因子：
3.4
通讯作者：
Ito, Takashi
中科院分区：
文献类型：
--
作者：
Kato, Mitsunori;Kito, Keiji;Ito, Takashi
泛素化不仅调节底物蛋白的稳定性，还调节其定位和活性，这些底物蛋白参与了大量的细胞过程。Skp 1-Cullin-F-box蛋白（SCF）复合物构成了泛素蛋白连接酶的主要家族，在每个成员中，F-box蛋白作为负责底物识别的可变组分，从而定义了每个复合物的功能。在这里，我们研究了SCF复合物中的F-box蛋白的组成是否在不同条件下被重塑。我们利用稳定同位素标记和MS对从处于对数期和二次发育期后的芽殖酵母细胞中大量亲和纯化的SCF复合物中的F-box蛋白进行相对定量，并揭示了Saf 1（一种参与进入的F-box蛋白）的增加。在二次发育转变期间进入静止期。同样，我们发现Met 4过表达诱导Met 30的特异性增加，Met 30是负责Met 4泛素化的F-box蛋白。这些结果说明了SCF复合物介导的泛素化系统通过重塑对环境和遗传扰动的细胞反应。掺入的F-box蛋白的组成改变可能会将该系统的活性重定向到适当的底物，以便在个体条件下泛素化，以维持细胞内稳态。
Ubiquitination regulates not only the stability but the localization and activity of substrate proteins involved in a plethora of cellular processes, The Skp1-Cullin-F-box protein (SCF) complexes constitute a major family of ubiquitin protein ligases, in each member of which an F-box protein serves as the variable component responsible for substrate recognition, thereby defining the function of each complex. Here we studied whether the composition of F-box proteins in the SCF complexes is remodeled under different conditions. We exploited stable isotope labeling and MS for relative quantification of F-box proteins in the SCF complexes affinity-purified en masse from budding yeast cells at log and post-diauxic phases, and revealed an increment of Saf1, an F-box protein involved in entry into quiescence, during the diauxic shift. Similarly, we found that Met4 overexpression induces a specific increment of Met30, the F-box protein responsible for ubiquitination of Met4. These results illustrate a cellular response to environmental and genetic perturbations through remodeling of the SCF complex-mediated ubiquitination system. Compositional alteration of incorporated F-box proteins may redirect the activity of this system toward appropriate substrates to be ubiquitinated under individual conditions for the maintenance of cellular homeostasis.