Upf1 potentially serves as a RING-related E3 ubiquitin ligase via its association with Upf3 in yeast.
Upf1 potentially serves as a RING-related E3 ubiquitin ligase via its association with Upf3 in yeast.
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DOI：
10.1261/rna.536308
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发表时间：
2008-09
期刊：
影响因子：
4.5
通讯作者：
Shinya Takahashi;Y. Araki;Y. Ohya;T. Sakuno;S. Hoshino;K. Kontani;H. Nishina;T. Katada
中科院分区：
文献类型：
--
作者：
Shinya Takahashi;Y. Araki;Y. Ohya;T. Sakuno;S. Hoshino;K. Kontani;H. Nishina;T. Katada
三种UPF蛋白在无意义介导的信使核糖核酸衰变(NMD)途径中是必不可少的。虽然这些蛋白质组装在多聚体上，以识别含有提前终止密码子的异常mRNAs，但这种组装的意义仍有待阐明。UPF1富含半胱氨酸和组氨酸的重复N末端(CH结构域)与UPf2的结合有关。在这里，我们证明了CH结构域在酵母中也扮演了UPF1展示E3泛素连接酶活性的环相关角色。尽管与典型的E3-环指序列有差异，但酵母UPF1的CH结构域与酵母E2 Ubc3特异性和直接相互作用。有趣的是，UPF1作为体外自我泛素化的底物，这种修饰需要它与Upf3而不是Upf2结合。CH区配位半胱氨酸及其残基的取代不仅损害了UPF1的自身泛素化，而且还损害了异常mRNAs的快速衰变。这些结果表明，UPF1可能作为E3泛素连接酶与UP3结合，在NMD途径的信号转导中发挥重要作用。
Three Upf proteins are essential to the nonsense-mediated mRNA decay (NMD) pathway. Although these proteins assemble on polysomes for recognition of aberrant mRNAs containing premature termination codons, the significance of this assembly remains to be elucidated. The Cys- and His-rich repeated N terminus (CH domain) of Upf1 has been implicated in its binding to Upf2. Here, we show that CH domain also plays a RING-related role for Upf1 to exhibit E3 ubiquitin ligase activity in yeast. Despite the sequence divergence from typical E3-RING fingers, the CH domain of yeast Upf1 specifically and directly interacted with the yeast E2 Ubc3. Interestingly, Upf1 served as a substrate for the in vitro self-ubiquitination, and the modification required its association with Upf3 rather than Upf2. Substitution of the coordinated Cys and His residues in the CH domain impaired not only self-ubiquitination of Upf1 but also rapid decay of aberrant mRNAs. These results suggest that Upf1 may serve as an E3 ubiquitin ligase upon its association with Upf3 and play an important role in signaling to the NMD pathway.