Structural 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.
Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 70101, Taiwan; Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan 70101, Taiwan. Electronic address: firstname.lastname@example.org.