Ubiquitin chain trimming recycles the substrate binding sites of the 26 S proteasome and promotes degradation of lysine 48-linked polyubiquitin conjugates.

ABSTRACT: The 26 S proteasome possesses two distinct deubiquitinating activities. The ubiquitin (Ub) chain amputation activity removes the entire polyUb chain from the substrates. The Ub chain trimming activity progressively cleaves a polyUb chain from the distal end. The Ub chain amputation activity mediates degradation-coupled deubiquitination. The Ub chain trimming activity can play a supportive or an inhibitory role in degradation, likely depending on features of the substrates. How Ub chain trimming assists degradation is not clear. We find that inhibition of the chain trimming activity of the 26 S proteasome with Ub aldehyde significantly inhibits degradation of Ub₄ (Lys-48)-UbcH10 and causes accumulation of free Ub₄ (generated from chain amputation) that can be retained on the proteasome. Als

SUBMITTER: Zhang NY 

PROVIDER: S-EPMC3138263 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature