Structural Insights into Linear Tri-ubiquitin Recognition by A20-Binding Inhibitor of NF-kappa B, ABIN-2Lin, S.M., Lin, S.C., Hong, J.Y., Su, T.W., Kuo, B.J., Chang, W.H., Tu, Y.F., Lo, Y.C.
(2017) Structure 25: 66-78
- PubMed: 27916521
- DOI: 10.1016/j.str.2016.11.005
- PubMed Abstract:
Recognition of linear polyubiquitin by specific ubiquitin-binding proteins plays an important role in mediating nuclear factor-κB (NF-κB) signaling. A20 binding proteins, ABINs, recognize linear polyubiquitin and A20 through UBAN and AHD1, respective ...
Recognition of linear polyubiquitin by specific ubiquitin-binding proteins plays an important role in mediating nuclear factor-κB (NF-κB) signaling. A20 binding proteins, ABINs, recognize linear polyubiquitin and A20 through UBAN and AHD1, respectively, for the inhibition of NF-κB activation. Here we report the crystal structure of the AHD1-UBAN fragment of ABIN2 in complex with linear tri-ubiquitin, which reveals a 2:1 stoichiometry of the complex. Structural analyses together with mutagenesis, pull-down, and isothermal titration calorimetry assays show that the hABIN2:tri-ubiquitin interaction is mainly through the primary ubiquitin-binding site, and also through the secondary ubiquitin-binding site under a high local protein concentration. Surprisingly, three ubiquitin units could form a right-handed helical trimer to bridge two ABIN2 dimers. The residues around the M1-linkage are crucial for ABIN2 to recognize tri-ubiquitin. The tri-ubiquitin bridging two ABIN2 dimers model suggests a possible higher-order signaling complex assembled between M1-linked polyubiquitinated proteins, ubiquitin-binding proteins, and effector signaling proteins in signal transduction.
Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 70101, Taiwan.