Work

Affinity Purification of the Arabidopsis 26 S Proteasome Reveals a Diverse Array of Plant Proteolytic Complexes

Year: 2010

Type: article

Abstract: Selective proteolysis in plants is largely mediated by the ubiquitin (Ub)/proteasome system in which substrates, marked by the covalent attachment of Ub, are degraded by the 26 S proteasome. The 26 S proteasome is composed of two subparticles, the 20 S core protease (CP) that compartmentalizes the protease active sites and the 19 S regulatory particle that recognizes and translocates appropriate substrates into the CP lumen for breakdown. Here, we describe an affinity method to rapidly purify epitope-tagged 26 S proteasomes intact from Arabidopsis thaliana. In-depth mass spectrometric analyses of preparations generated from young seedlings confirmed that the 2.5-MDa CP-regulatory particle complex is actually a heterogeneous set of particles assembled with paralogous pairs for most subunits. A number of these subunits are modified post-translationally by proteolytic processing, acetylation, and/or ubiquitylation. Several proteasome-associated proteins were also identified that likely assist in complex assembly and regulation. In addition, we detected a particle consisting of the CP capped by the single subunit PA200 activator that may be involved in Ub-independent protein breakdown. Taken together, it appears that a diverse and highly dynamic population of proteasomes is assembled in plants, which may expand the target specificity and functions of intracellular proteolysis.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m110.136622

Authors: Adam J. Book, Nicholas P. Gladman, Sang-Sook Lee, Mark Scalf, Lloyd M. Smith, Richard D. Vierstra

Institution: University of Wisconsin–Madison

Language: English

Topic: Ubiquitin and proteasome pathways

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,430