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Publication Abstract from PubMed

The 20S core particle of the eukaryotic proteasome is composed of two alpha- and two beta-rings, each of which is a hetero-heptamer composed of seven homologous but distinct subunits. Although formation of the eukaryotic proteasome is a highly ordered process assisted by assembly chaperones, alpha7, an alpha-ring component, has the unique property of self-assembling into a homo-tetradecamer. We used biophysical methods to characterize the oligomeric states of this proteasome subunit and its interaction with alpha6, which makes direct contacts with alpha7 in the proteasome alpha-ring. We determined a crystal structure of the alpha7 tetradecamer, which has a double-ring structure. Sedimentation velocity analytical ultracentrifugation and mass spectrometric analysis under non-denaturing conditions revealed that alpha7 exclusively exists as homo-tetradecamer in solution and that its double-ring structure is disassembled upon the addition of alpha6, resulting in a 1:7 hetero-octameric alpha6-alpha7 complex. Our findings suggest that proteasome formation involves the disassembly of non-native oligomers, which are assembly intermediates.

Disassembly of the self-assembled, double-ring structure of proteasome alpha7 homo-tetradecamer by alpha6.,Ishii K, Noda M, Yagi H, Thammaporn R, Seetaha S, Satoh T, Kato K, Uchiyama S Sci Rep. 2015 Dec 14;5:18167. doi: 10.1038/srep18167. PMID:26657688^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.