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Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation
Author(s) -
Yahalom Avital,
Kim TaeHoun,
Roy Bijoyita,
Singer Ruth,
Von Arnim Albrecht G.,
Chamovitz Daniel A.
Publication year - 2008
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03347.x
Subject(s) - cop9 signalosome , arabidopsis , protein subunit , initiation factor , eukaryotic translation , proteasome , translation (biology) , biology , immunoprecipitation , microbiology and biotechnology , computational biology , mutant , genetics , gene , biochemistry , messenger rna , protease , peptide hydrolases , enzyme
Summary The roles of individual eukaryotic translation initiation factor 3 (eIF3) subunits are largely unclear, although some are essential, while others are thought to have regulatory roles. The ‘e’ subunit, also known as Int‐6/Int6, is a candidate for a regulatory subunit as it is not essential for translation initiation in yeasts. eIF3e associates with the COP9 signalosome, and localizes to the nucleus in certain tissues. To further elucidate the roles of eIF3e, we have taken a genetic approach using Arabidopsis as a model system. Overexpression of eIF3e results in defects similar to mutations in the COP9 signalosome. eIF3e protein, but not transcript, over accumulates in csn mutants, and eIF3e is degraded in a proteasome‐dependent fashion. In vitro and in vivo assays suggest that excess eIF3e inhibits translation. We conclude that the COP9 signalosome maintains a precise regulation of eIF3e levels, which is necessary for normal development in Arabidopsis.