2JY6

Solution structure of the complex of ubiquitin and ubiquilin 1 UBA domain

Summary for 2JY6

• Entry DOI: 10.2210/pdb2jy6/pdb
• Related: 2JY5
• Descriptor: Ubiquitin protein, Ubiquilin-1 (2 entities in total)
• Functional Keywords: ubiquilin, uba, ubiquitin, complex, alternative splicing, cytoplasm, nucleus, phosphoprotein, proteasome, signaling protein
• Biological source: Homo sapiens (human); More
• Cellular location: Cytoplasm: Q9UMX0
• Total number of polymer chains: 2
• Total formula weight: 14211.06

Authors

Zhang, D.,Raasi, S.,Fushman, D. (deposition date: 2007-12-06, release date: 2008-03-18, Last modification date: 2024-05-29)

Primary citation

Zhang, D.,Raasi, S.,Fushman, D.
Affinity makes the difference: nonselective interaction of the UBA domain of Ubiquilin-1 with monomeric ubiquitin and polyubiquitin chains
J.Mol.Biol., 377:162-180, 2008

PubMed Abstract: Ubiquilin/PLIC proteins belong to the family of UBL-UBA proteins implicated in the regulation of the ubiquitin-dependent proteasomal degradation of cellular proteins. A human presenilin-interacting protein, ubiquilin-1, has been suggested as potential therapeutic target for treating Huntington's disease. Ubiquilin's interactions with mono- and polyubiquitins are mediated by its UBA domain, which is one of the tightest ubiquitin binders among known ubiquitin-binding domains. Here we report the three-dimensional structure of the UBA domain of ubiquilin-1 (UQ1-UBA) free in solution and in complex with ubiquitin. UQ1-UBA forms a compact three-helix bundle structurally similar to other known UBAs, and binds to the hydrophobic patch on ubiquitin with a K(d) of 20 microM. To gain structural insights into UQ1-UBA's interactions with polyubiquitin chains, we have mapped the binding interface between UQ1-UBA and Lys48- and Lys63-linked di-ubiquitins and characterized the strength of UQ1-UBA binding to these chains. Our NMR data show that UQ1-UBA interacts with the individual ubiquitin units in both chains in a mode similar to its interaction with mono-ubiquitin, although with an improved binding affinity for the chains. Our results indicate that, in contrast to UBA2 of hHR23A that has strong binding preference for Lys48-linked chains, UQ1-UBA shows little or no binding selectivity toward a particular chain linkage or between the two ubiquitin moieties in the same chain. The structural data obtained in this study provide insights into the possible structural reasons for the diversity of polyubiquitin chain recognition by UBA domains.

PubMed: 18241885
DOI: 10.1016/j.jmb.2007.12.029

Experimental method

SOLUTION NMR