Download MendeleyCryo-EM structures of UBA6 reveal mechanisms of E1-E2 specificity and dual FAT10/ubiquitin thioester transfer.
Nayak, D., Jia, L., Dos Santos Bury, P., Ruben, E.A., Shukla, A., Nayak, A., Stratton, C.M., Ebadi, P., Cho, H., Tumanova, A.A., Varughese, J.T., Yuan, L., Gao, F., Cano, K.E., Davies, C., Sung, P., Gack, M.U., Wasmuth, E.V., Olsen, S.K.(2026) Nat Commun 17
- PubMed: 41764162 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1038/s41467-026-69882-3
- Primary Citation Related Structures:
9YKV, 9YKW, 9YLB, 9YLF - PubMed Abstract:
UBA1 and UBA6 define parallel ubiquitin (Ub) activation systems that perform non-overlapping roles in Ub and ubiquitin-like protein (Ubl) signaling. Whereas UBA1 supports the canonical Ub pathway, UBA6 also activates the Ubl FAT10, linking Ub signaling to immune-regulated proteostasis. In addition to selective Ub/Ubl activation, UBA1 and UBA6 engage distinct sets of E2s, yet how these enzymes achieve selective E2 engagement has remained unclear. Using chemical trapping and high-resolution cryo-EM, we determine four structures of UBA6-E2 complexes representing the thioester-transfer step with either FAT10 or Ub, revealing how this E1 distinguishes its cognate partners. UBA6 achieves E2 specificity through coordinated contributions of the UFD and SCCH domains, a dual-domain mechanism that contrasts with the UFD-dominated selectivity of UBA1. The structures further show that an existing inositol hexakisphosphate (InsP₆)-binding site, unique to UBA6, stabilizes an expanded SCCH cleft that pre-organizes the enzyme for selective engagement of UBA6-specific E2s. These findings define principles for E1-E2 recognition and identify InsP₆ as a cofactor shaping specificity within the Ub-like conjugation network.
- Department of Biochemistry & Structural Biology and Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
Organizational Affiliation:
