Structures of the cIAP2 RING Domain Reveal Conformational Changes Associated with Ubiquitin-conjugating Enzyme (E2) Recruitment
Structures of the cIAP2 RING Domain Reveal Conformational Changes Associated with Ubiquitin-conjugating Enzyme (E2) Recruitment
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DOI：
10.1074/jbc.m804753200
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发表时间：
2008-11-14
影响因子：
4.8
通讯作者：
Day, Catherine L.
中科院分区：
文献类型：
--
作者：
Mace, Peter D.;Linke, Katrin;Day, Catherine L.
细胞凋亡抑制因子（IAP）蛋白是细胞死亡的关键负调节因子，在许多癌症中高度表达。与IAP蛋白结合的拮抗剂引起的细胞死亡与其泛素化和降解有关。IAP蛋白C端的RING结构域是关键。在这里，我们报告的晶体结构cIAP 2环域同源二聚体单独，并结合到泛素结合（E2）酶UbcH 5 b。这些结构表明RING结构域的微小变化伴随着E2结合。通过突变E2结合表面的残基，我们表明，autoubiquitylation是必需的IAP丰度的调节。二聚体的形成也是至关重要的，并且单个C-末端残基的突变废除了二聚体的形成，并且E3连接酶活性降低。我们进一步证明，破坏E2结合，或二聚化，稳定IAP蛋白对IAP拮抗剂在体内。
Inhibitor of apoptosis (IAP) proteins are key negative regulators of cell death that are highly expressed in many cancers. Cell death caused by antagonists that bind to IAP proteins is associated with their ubiquitylation and degradation. The RING domain at the C terminus of IAP proteins is pivotal. Here we report the crystal structures of the cIAP2 RING domain homodimer alone, and bound to the ubiquitin-conjugating (E2) enzyme UbcH5b. These structures show that small changes in the RING domain accompany E2 binding. By mutating residues at the E2-binding surface, we show that autoubiquitylation is required for regulation of IAP abundance. Dimer formation is also critical, and mutation of a single C-terminal residue abrogated dimer formation and E3 ligase activity was diminished. We further demonstrate that disruption of E2 binding, or dimerization, stabilizes IAP proteins against IAP antagonists in vivo.