Hu Lin, Xu Jiafeng, Xie Xiaomei, Zhou Yiwen, Tao Panfeng, Li Haidong, Han Xu, Wang Chong, Liu Jian, Xu Pinglong, Neculai Dante, Xia Zongping
Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310027, China.
Department of Surgical Oncology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310027, China.
Nat Commun. 2017 Oct 9;8(1):814. doi: 10.1038/s41467-017-01290-0.
Ubiquitin ligase TRAF6, together with ubiquitin-conjugating enzyme Ubc13/Uev1, catalyzes processive assembly of unanchored K63-linked polyubiquitin chains for TAK1 activation in the IL-1R/TLR pathways. However, what domain and how it functions to enable TRAF6's processivity are largely uncharacterized. Here, we find TRAF6 coiled-coil (CC) domain is crucial to enable its processivity. The CC domain mediates TRAF6 oligomerization to ensure efficient long polyubiquitin chain assembly. Mutating or deleting the CC domain impairs TRAF6 oligomerization and processive polyubiquitin chain assembly. Fusion of the CC domain to the E3 ubiquitin ligase CHIP/STUB1 renders the latter capable of NF-κB activation. Moreover, the CC domain, after oligomerization, interacts with Ubc13/UbUbc13, which further contributes to TRAF6 processivity. Point mutations within the CC domain that weaken TRAF6 interaction with Ubc13/UbUbc13 diminish TRAF6 processivity. Our results reveal that the CC oligomerization primes its interaction with Ubc13/UbUbc13 to confer processivity to TRAF6 ubiquitin ligase activity.Ubiquitin ligase TRAF6 catalyzes assembly of free polyubiquitin chains for TAK1 activation in the IL-1R/TLR pathways, but the mechanism underlying its processivity is unclear. Here, the authors show that TRAF6 coiled-coil oligomerization domain primes its interaction with Ubc13/UbUbc13 to confer processivity.
泛素连接酶TRAF6与泛素结合酶Ubc13/Uev1一起，催化在IL-1R/TLR信号通路中为激活TAK1而进行的非锚定K63连接的多聚泛素链的持续组装。然而，TRAF6的哪个结构域以及它如何发挥作用来实现其持续性在很大程度上尚不清楚。在这里，我们发现TRAF6卷曲螺旋（CC）结构域对于实现其持续性至关重要。CC结构域介导TRAF6寡聚化以确保高效的长多聚泛素链组装。突变或删除CC结构域会损害TRAF6寡聚化和持续性多聚泛素链组装。将CC结构域与E3泛素连接酶CHIP/STUB1融合，使后者能够激活NF-κB。此外，CC结构域在寡聚化后与Ubc13/UbUbc13相互作用，这进一步促进了TRAF6的持续性。CC结构域内削弱TRAF6与Ubc13/UbUbc13相互作用的点突变会降低TRAF6的持续性。我们的结果表明，CC寡聚化引发了其与Ubc13/UbUbc13的相互作用，从而赋予TRAF6泛素连接酶活性以持续性。泛素连接酶TRAF6在IL-1R/TLR信号通路中催化游离多聚泛素链的组装以激活TAK1，但其持续性的潜在机制尚不清楚。在这里，作者表明TRAF6卷曲螺旋寡聚化结构域引发了其与Ubc13/UbUbc13的相互作用以赋予持续性。
