The linear ubiquitin chain assembly complex (LUBAC) generates heterotypic ubiquitin chains.
The linear ubiquitin chain assembly complex (LUBAC) generates heterotypic ubiquitin chains.
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DOI：
10.7554/elife.60660
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发表时间：
2021-06-18
期刊：
影响因子：
7.7
通讯作者：
Ikeda F
中科院分区：
文献类型：
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作者：
Rodriguez Carvajal A;Grishkovskaya I;Gomez Diaz C;Vogel A;Sonn-Segev A;Kushwah MS;Schodl K;Deszcz L;Orban-Nemeth Z;Sakamoto S;Mechtler K;Kukura P;Clausen T;Haselbach D;Ikeda F
线性泛素链组装复合体(LUBAC)是唯一已知的用于线性/MET1连接的泛素链形成的泛素连接酶。LUBAC组分之一，血红素氧化的IRP2泛素连接酶1(HOIL-1L)，最近被发现催化泛素与一些底物之间形成氧酯键。然而，在LUBAC的背景下，没有直接观察到氧酯键的形成。在这里，我们提出了第一个通过电子显微镜获得的人LUBAC的三维重建，并报告了它产生的异型泛素链，包含与氧酯连接的分支的线性连接。我们发现这一事件依赖于HOIL-1L的催化活性。通过交联质谱显示催化环中环(RBR)结构域之间的接近，提出了HOIL-1相互作用蛋白(HOIP)和HOIL-1L连接酶之间的协调泛素传递机制。在小鼠胚胎成纤维细胞中，这些异型链是由肿瘤坏死因子诱导的，而在表达HOIL-1L催化失活突变体的细胞中，肿瘤坏死因子被减少。总之，我们证明了LUBAC通过HOIP和HOIL-1L的协同作用组装了异型泛素链。
The linear ubiquitin chain assembly complex (LUBAC) is the only known ubiquitin ligase for linear/Met1-linked ubiquitin chain formation. One of the LUBAC components, heme-oxidized IRP2 ubiquitin ligase 1 (HOIL-1L), was recently shown to catalyse oxyester bond formation between ubiquitin and some substrates. However, oxyester bond formation in the context of LUBAC has not been directly observed. Here, we present the first 3D reconstruction of human LUBAC obtained by electron microscopy and report its generation of heterotypic ubiquitin chains containing linear linkages with oxyester-linked branches. We found that this event depends on HOIL-1L catalytic activity. By cross-linking mass spectrometry showing proximity between the catalytic RING-in-between-RING (RBR) domains, a coordinated ubiquitin relay mechanism between the HOIL-1-interacting protein (HOIP) and HOIL-1L ligases is suggested. In mouse embryonic fibroblasts, these heterotypic chains were induced by TNF, which is reduced in cells expressing an HOIL-1L catalytic inactive mutant. In conclusion, we demonstrate that LUBAC assembles heterotypic ubiquitin chains by the concerted action of HOIP and HOIL-1L.