Premium
Appropriate interaction of Ecm29 with the proteasome is necessary for proteasome functional integrity and requires the Not4 E3 ligase
Author(s) -
Collart Martine A
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.908.1
Subject(s) - proteasome , ubiquitin , deubiquitinating enzyme , ubiquitin ligase , microbiology and biotechnology , biology , protein degradation , chaperone (clinical) , biochemistry , chemistry , gene , medicine , pathology
In this study we determine that Not4 is important for ubiquitin turnover and affects proteasome integrity, in part through Ecm29, a protein that contributes to the assembly of the proteasome. Deletion of Not4 leads to accumulation of polyubiquitinated proteins, reduced levels of free ubiquitin and synthetic lethality when combined with the deletion of the Doa4 or Ubp6 deubiquitinating enzymes. Consistently, purification of the proteasome in the absence of Not4 reveals functional, salt‐resistant interaction between the proteasome regulatory particle, RP, and the proteasome core particle, CP, and instability of all other forms of RP. Purification of proteasome holoenzyme via RP reveals co‐purification of Ecm29 from wild type cells, but much less from not4 cells. Indeed, in the absence of Not4, Ecm29 interacts less well with the proteasome, gets ubiquitinated and degraded Interestingly, Ecm29 was mostly identified in purified RP‐containing complexes that are inactive, and are not detectable in cells lacking Not4. On the other hand, Ecm29 co‐purifies with the Ccr4‐Not complex and co‐immunoprecipitates with Not4. Our results characterize Ecm29 as a proteasome chaperone whose appropriate interaction with the proteasome requires Not4. This work was supported by the Swiss Natinal Science Foundation.