Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.
Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115.
Proc Natl Acad Sci U S A. 2018 Feb 20;115(8):1783-1788. doi: 10.1073/pnas.1721788115. Epub 2018 Feb 5.
Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) plays a vital role in immune signal transduction pathways by acting as a ubiquitin ligase (E3) for Lys63-linked polyubiquitin chain synthesis. However, the detailed mechanism by which the TRAF6 RING dimer promotes ubiquitin transfer was unknown. Through structural modeling and biochemical analysis, we here show that the TRAF6 RING dimer employs a concerted allosteric mechanism using both subunits of the TRAF6 dimer to promote ubiquitin (Ub) transfer. In particular, we reveal the importance of the C-terminal extension of the TRAF6 RING domain that mediates -interactions with the donor-Ub. By analyzing structures and models of E3s in complex with Ub-loaded ubiquitin-conjugating enzymes (E2s), we further highlight the roles of N-terminal and C-terminal extensions beyond the bona fide RING domains in promoting Ub transfer through engagement with a donor-Ub in and , respectively.
肿瘤坏死因子 (TNF) 受体相关因子 6 (TRAF6) 通过作为 Lys63 连接多泛素链合成的泛素连接酶 (E3) 在免疫信号转导途径中发挥重要作用。然而，TRAF6 RING 二聚体促进泛素转移的详细机制尚不清楚。通过结构建模和生化分析，我们在此表明 TRAF6 RING 二聚体采用协调变构机制，利用 TRAF6 二聚体的两个亚基来促进泛素 (Ub) 转移。特别是，我们揭示了 TRAF6 RING 结构域 C 末端延伸的重要性，该延伸介导与供体-Ub 的 -相互作用。通过分析与负载泛素的泛素结合酶 (E2) 结合的 E3s 的结构和模型，我们进一步强调了 N 末端和 C 末端延伸在通过与供体-Ub 结合分别在 和 中促进 Ub 转移中的作用。
