RING Dimerization Links Higher-Order Assembly of TRIM5α to Synthesis of K63-Linked Polyubiquitin

• Published in: Cell reports (Cambridge) 2015-08, Vol.12 (5), p.788-797
• Main Authors: Yudina, Zinaida, Roa, Amanda, Johnson, Rory, Biris, Nikolaos, de Souza Aranha Vieira, Daniel A., Tsiperson, Vladislav, Reszka, Natalia, Taylor, Alexander B., Hart, P. John, Demeler, Borries, Diaz-Griffero, Felipe, Ivanov, Dmitri N.
• Format: Article
• Language: English
• Subjects: Animals; BASIC BIOLOGICAL SCIENCES; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cells, Cultured; Dogs; Polyubiquitin - biosynthesis; Polyubiquitin - genetics; Protein Multimerization - physiology; Retroviridae - genetics; Retroviridae - metabolism; Ubiquitin-Conjugating Enzymes - genetics; Ubiquitin-Conjugating Enzymes - metabolism; Viral Proteins - genetics; Viral Proteins - metabolism
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2015.06.072

Members of the tripartite motif (TRIM) protein family of RING E3 ubiquitin (Ub) ligases promote innate immune responses by catalyzing synthesis of polyubiquitin chains linked through lysine 63 (K63). Here, we investigate the mechanism by which the TRIM5α retroviral restriction factor activates Ubc13, the K63-linkage-specific E2. Structural, biochemical, and functional characterization of the TRIM5α:Ubc13-Ub interactions reveals that activation of the Ubc13-Ub conjugate requires dimerization of the TRIM5α RING domain. Our data explain how higher-order oligomerization of TRIM5α, which is promoted by the interaction with the retroviral capsid, enhances the E3 Ub ligase activity of TRIM5α and contributes to its antiretroviral function. This E3 mechanism, in which RING dimerization is transient and depends on the interaction of the TRIM protein with the ligand, is likely to be conserved in many members of the TRIM family and may have evolved to facilitate recognition of repetitive epitope patterns associated with infection. [Display omitted] •Crystal structure of the TRIM5α RING:Ubc13 complex reveals RING dimerization•RING dimerization is required for synthesis of K63-linked polyubiquitin by TRIM5α•Mutation of the dimer interface impairs TRIM5α-mediated retroviral restriction Yudina et al. report that transient dimerization of the RING domain contributes to the function of the TRIM5α retroviral restriction factor. In the proposed mechanism, synthesis of K63-linked polyubiquitin is promoted by a molecular pattern consisting of multiple TRIM-binding epitopes present in proximity to each other.