A ubiquitin ligase complex assembles linear polyubiquitin chains
A ubiquitin ligase complex assembles linear polyubiquitin chains
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DOI：
10.1038/sj.emboj.7601360
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发表时间：
2006-10-18
期刊：
影响因子：
11.4
通讯作者：
Iwai, Kazuhiro
中科院分区：
文献类型：
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作者：
Kirisako, Takayoshi;Kamei, Kiyoko;Iwai, Kazuhiro
泛素系统通过将泛素结合到靶蛋白上，在许多细胞过程的调节中起重要作用。在大多数情况下，多聚泛素与靶蛋白的缀合调节其功能。在迄今为止报道的多聚泛素链中，泛素单体通过内部Lys和C-末端Gly之间的异肽键连接。在这里，我们报告说，由两个环指蛋白，HOIL-1 L和HOIP，表现出泛素聚合活性的蛋白质识别泛素部分。复合物产生的多聚泛素链不是由赖氨酸连接形成的，而是由泛素的C-和N-末端之间的连接形成的，这表明连接酶复合物具有独特的功能来组装新的头到尾的线性多聚泛素链。此外，该复合物调节Ub-GFP（具有N-末端泛素的GFP融合蛋白）的稳定性。后降解产生的线性多聚泛素链可能作为一种新的蛋白质调节剂发挥作用。
The ubiquitin system plays important roles in the regulation of numerous cellular processes by conjugating ubiquitin to target proteins. In most cases, conjugation of polyubiquitin to target proteins regulates their function. In the polyubiquitin chains reported to date, ubiquitin monomers are linked via isopeptide bonds between an internal Lys and a C-terminal Gly. Here, we report that a protein complex consisting of two RING finger proteins, HOIL-1L and HOIP, exhibits ubiquitin polymerization activity by recognizing ubiquitin moieties of proteins. The polyubiquitin chain generated by the complex is not formed by Lys linkages, but by linkages between the C- and N-termini of ubiquitin, indicating that the ligase complex possesses a unique feature to assemble a novel head-to-tail linear polyubiquitin chain. Moreover, the complex regulates the stability of Ub-GFP (a GFP fusion protein with an N-terminal ubiquitin). The linear polyubiquitin chain generated post-translationally may function as a new modulator of proteins.