PMID: 20826778

Authors:

Ko S, Kang GB, Song SM, Lee JG, Shin DY, Yoon J, Sheng Y, Cheong C, Jeon YH, Jung YK, Arrowsmith CH, Avvakumov GV, Dhe-Paganon S, Yoo YJ, Eom SH, Lee W

Title:

Structural basis of E2-25K/UBB+1 interaction leading to proteasome inhibition and neurotoxicity.

Journal:

J Biol Chem. 2010 Sep 8.

Abstract:

E2-25K/Hip2 is an unusual ubiquitin-conjugating enzyme that interacts with the frameshift mutant of ubiquitin B (UBB+1) and has been identified as a crucial factor regulating amyloid-beta neurotoxicity. To study the structural basis of the neurotoxicity mediated by the E2-25K/UBB+1 interaction, we determined the three-dimensional structures of UBB+1, E2 25K and the E2-25K/Ubiquitin and E2-25K/UBB+1 complexes. The structures revealed that ubiquitin or UBB+1 is bound to E2-25K via the enzyme's MGF motif and residues in alpha 9 of the enzyme. Polyubiquitylation assays, together with analyses of various E2-25K mutants, showed that disrupting UBB+1 binding markedly diminishes synthesis of neurotoxic UBB+1 anchored polyUb. These results suggest that the interaction between E2-25K and UBB+1 is critical for the synthesis and accumulation of UBB+1-anchored polyUb, which results in proteasomal inhibition and neuronal cell death.