Ito T, Matsui Y, Ago T, Ota K, Sumimoto H
Division of Genome Biology, Cancer Research Institute, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-0934, Japan.
EMBO J. 2001 Aug 1;20(15):3938-46. doi: 10.1093/emboj/20.15.3938.
Modular domains mediating specific protein-protein interactions play central roles in the formation of complex regulatory networks to execute various cellular activities. Here we identify a novel domain PB1 in the budding yeast protein Bem1p, which functions in polarity establishment, and mammalian p67(phox), which activates the microbicidal phagocyte NADPH oxidase. Each of these specifically recognizes an evolutionarily conserved PC motif to interact directly with Cdc24p (an essential protein for cell polarization) and p40(phox) (a component of the signaling complex for the oxidase), respectively. Swapping the PB1 domain of Bem1p with that of p67(phox), which abolishes its interaction with Cdc24p, confers on cells temperature- sensitive growth and a bilateral mating defect. These phenotypes are suppressed by a mutant Cdc24p harboring the PC motif-containing region of p40(phox), which restores the interaction with the altered Bem1p. This domain-swapping experiment demonstrates that Bem1p function requires interaction with Cdc24p, in which the PB1 domain and the PC motif participate as responsible modules.
介导特定蛋白质-蛋白质相互作用的模块化结构域在形成执行各种细胞活动的复杂调控网络中发挥核心作用。在此,我们在芽殖酵母蛋白Bem1p中鉴定出一个新的结构域PB1,它在极性建立中起作用,以及在哺乳动物p67(phox)中,它激活杀菌性吞噬细胞NADPH氧化酶。这些蛋白中的每一个都特异性识别一个进化上保守的PC基序,分别与Cdc24p(细胞极化的必需蛋白)和p40(phox)(氧化酶信号复合物的一个组分)直接相互作用。将Bem1p的PB1结构域与p67(phox)的PB1结构域交换,这消除了它与Cdc24p的相互作用,赋予细胞温度敏感型生长和双边交配缺陷。这些表型被一个携带p40(phox)含PC基序区域的突变型Cdc24p所抑制,该突变型Cdc24p恢复了与改变后的Bem1p的相互作用。这个结构域交换实验表明,Bem1p功能需要与Cdc24p相互作用,其中PB1结构域和PC基序作为负责的模块参与其中。