Chan Yaru, Yoon Jeongsook, Wu June-Tai, Kim Hyung-Jun, Pan Kuan-Ting, Yim Jeongbin, Chien Cheng-Ting
Institute of Molecular Biology, Academia Sinica, 128 Sec No. 2 Academia Road, Taipei 115, Taiwan.
J Cell Sci. 2008 Oct 1;121(Pt 19):3218-23. doi: 10.1242/jcs.030445. Epub 2008 Sep 9.
The ubiquitin-like protein Nedd8/Rub1 covalently modifies and activates cullin ubiquitin ligases. However, the repertoire of Nedd8-modified proteins and the regulation of protein neddylation status are not clear. The cysteine protease DEN1/NEDP1 specifically processes the Nedd8 precursor and has been suggested to deconjugate Nedd8 from cullin proteins. By characterizing the Drosophila DEN1 protein and DEN1 null (DEN1(null)) mutants, we provide in vitro and in vivo evidence that DEN1, in addition to processing Nedd8, deneddylates many cellular proteins. Although purified DEN1 protein efficiently deneddylates the Nedd8-conjugated cullin proteins Cul1 and Cul3, neddylated Cul1 and Cul3 protein levels are not enhanced in DEN1(null). Strikingly, many cellular proteins are highly neddylated in DEN1 mutants and are deneddylated by purified DEN1 protein. DEN1 deneddylation activity is distinct from that of the cullin-deneddylating CSN. Genetic analyses indicate that a balance between neddylation and deneddylation maintained by DEN1 is crucial for animal viability.
类泛素蛋白Nedd8/Rub1通过共价修饰激活cullin泛素连接酶。然而，Nedd8修饰蛋白的种类以及蛋白质Nedd8化状态的调控尚不清楚。半胱氨酸蛋白酶DEN1/NEDP1专门处理Nedd8前体，并被认为能使Nedd8与cullin蛋白去偶联。通过对果蝇DEN1蛋白和DEN1基因敲除（DEN1(null)）突变体进行表征，我们提供了体外和体内证据，表明DEN1除了处理Nedd8外，还能使许多细胞蛋白去Nedd8化。尽管纯化的DEN1蛋白能有效地使与Nedd8偶联的cullin蛋白Cul1和Cul3去Nedd8化，但在DEN1(null)中，Nedd8化的Cul1和Cul3蛋白水平并未升高。引人注目的是，许多细胞蛋白在DEN1突变体中高度Nedd8化，并能被纯化的DEN1蛋白去Nedd8化。DEN1的去Nedd8化活性与cullin去Nedd8化蛋白CSN的活性不同。遗传分析表明，由DEN1维持的Nedd8化和去Nedd8化之间的平衡对动物的生存能力至关重要。
