Download MendeleyStructural and Biochemical Basis for Higher-Order Assembly between A20-Binding Inhibitor of NF-kappa B 1 (ABIN1) and M1-Linked Ubiquitins.
Hong, J.Y., Lin, S.C., Kuo, B.J., Lo, Y.C.(2021) J Mol Biol 433: 167116-167116
- PubMed: 34161781
- DOI: https://doi.org/10.1016/j.jmb.2021.167116
- Primary Citation of Related Structures:
7EAL, 7EAO, 7EB9 - PubMed Abstract:
Polyubiquitination is important in controlling NF-κB signaling. Excessive NF-κB activity has been linked to inflammatory disorders and autoimmune diseases, while ABIN1 could attenuate NF-κB activation to maintain immune homeostasis by utilizing UBAN to recognize linear (M1)-linked polyubiquitinated NF-κB activation mediators, including NEMO, IRAK1 and RIP1. PolyUb-mediated UBAN recruitment remains undetermined, since the recognition studies focused mostly on di-ubiquitin (diUb). Here we report three crystal structures of human ABIN1 UBAN (hABIN1 UBAN ) in complex with M1-linked diUb, triUb, and tetraUb, respectively. Notably, the hABIN1 UBAN :diUb structure reveals that a diUb randomly binds one of the Ub-binding sites of the hABIN1 UBAN dimer and leaves the other site vacant. Together with the ITC and gel-filtration analyses, we found that M1-triUb and M1-tetraUb adopt two unique conformations, instead of an elongated one, and they preferentially use the N-terminal two-Ub unit to bind the primary Ub-binding site of a hABIN1 UBAN dimer and the C-terminal two-Ub unit to bind the secondary Ub-binding site of another hABIN1 UBAN dimer. Especially, our results suggest that two ABIN1 UBAN dimers cooperatively bind two UBAN-binding units of a tetraUb or vice versa. Since the UBAN family members share a conserved diUb-binding mode, our results suggest that M1-polyUb modification allows multiple copies of the two-tandem Ub unit to simultaneously coordinate multiple and/or different binding partners to increase their local concentrations and to facilitate the formation of a large signaling complex. Our study provides a structural-functional glimpse of M1-polyUb as a multiple-molecule binding platform to exert its intrinsic structural plasticity in mediating cellular signaling.
Organizational Affiliation:
Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 70101, Taiwan.
