Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA.
Mol Cell. 2010 Nov 12;40(3):433-43. doi: 10.1016/j.molcel.2010.10.018.
WD40-repeat β-propellers are found in a wide range of proteins involved in distinct biological activities. We define a large subset of WD40 β-propellers as a class of ubiquitin-binding domains. Using the β-propeller from Doa1/Ufd3 as a paradigm, we find the conserved top surface of the Doa1 β-propeller binds the hydrophobic patch of ubiquitin centered on residues I44, L8, and V70. Mutations that disrupt ubiquitin binding abrogate Doa1 function, demonstrating the importance of this interaction. We further demonstrate that WD40 β-propellers from a functionally diverse set of proteins bind ubiquitin in a similar fashion. This set includes members of the F box family of SCF ubiquitin E3 ligase adaptors. Using mutants defective in binding, we find that ubiquitin interaction by the F box protein Cdc4 promotes its autoubiquitination and turnover. Collectively, our results reveal a molecular mechanism that may account for how ubiquitin controls a broad spectrum of cellular activities.
WD40 重复β-螺旋桨存在于广泛参与不同生物活性的蛋白质中。我们将大量 WD40β-螺旋桨定义为一类泛素结合结构域。我们以 Doa1/Ufd3 的β-螺旋桨为例，发现 Doa1β-螺旋桨的保守顶表面结合了以残基 I44、L8 和 V70 为中心的泛素疏水区。破坏泛素结合的突变会使 Doa1 功能丧失，证明了这种相互作用的重要性。我们进一步证明，来自功能多样的蛋白质的 WD40β-螺旋桨以相似的方式结合泛素。这组蛋白包括 SCF 泛素 E3 连接酶衔接子的 F 盒家族成员。使用结合缺陷的突变体，我们发现 F 盒蛋白 Cdc4 与泛素的相互作用促进了其自身泛素化和周转。总的来说，我们的结果揭示了一种可能解释泛素如何控制广泛的细胞活动的分子机制。
