Molecular determinants of polyubiquitin linkage selection by an HECT ubiquitin ligase
Molecular determinants of polyubiquitin linkage selection by an HECT ubiquitin ligase
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DOI：
10.1038/sj.emboj.7601061
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发表时间：
2006-04-19
期刊：
影响因子：
11.4
通讯作者：
Pickart, Cecile M.
中科院分区：
文献类型：
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作者：
Wang, Min;Cheng, Dongmei;Pickart, Cecile M.
泛素 (Ub)-蛋白质连接酶 (E3) 经常用多聚泛素 (poly-Ub) 链形式的多个 Ub 分子修饰其底物。尽管结构不同的多聚 Ub 链（通过不同的 Ub 赖氨酸 (Lys) 残基连接）可以赋予靶蛋白不同的命运，但人们对 E3 如何选择用于链合成的 Lys 残基知之甚少。在这里，我们结合诱变、生物化学和质谱来绘制 KIAA10 催化的链组装中连锁选择的决定因素，KIAA10 是合成 K29 和 K48 连接链的 HECT（与 E6AP C 端同源）结构域 E3。着眼于为链形成提供赖氨酸残基的 Ub 分子，我们发现与 K48 和 K29 相邻的特定表面残基对于在链合成中使用各自的赖氨酸残基至关重要。这种直接的连锁选择机制与 Ubc9 催化的 sumoylation 中的底物位点选择机制相似，但与 Mms2/Ubc13（Ub E2 变体（UEV）/E2）复合物使用的链连锁选择机制不同。
Ubiquitin (Ub)-protein ligases (E3s) frequently modify their substrates with multiple Ub molecules in the form of a polyubiquitin (poly-Ub) chain. Although structurally distinct poly-Ub chains ( linked through different Ub lysine (Lys) residues) can confer different fates on target proteins, little is known about how E3s select the Lys residue to be used in chain synthesis. Here, we used a combination of mutagenesis, biochemistry, and mass spectrometry to map determinants of linkage choice in chain assembly catalyzed by KIAA10, an HECT (Homologous to E6AP C-Terminus) domain E3 that synthesizes K29- and K48-linked chains. Focusing on the Ub molecule that contributes the Lys residue for chain formation, we found that specific surface residues adjacent to K48 and K29 are critical for the usage of the respective Lys residues in chain synthesis. This direct mechanism of linkage choice bears similarities to the mechanism of substrate site selection in sumoylation catalyzed by Ubc9, but is distinct from the mechanism of chain linkage selection used by the Mms2/Ubc13 (Ub E2 variant (UEV)/E2) complex.