Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation.
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.
Yahalom
Avital
A
Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Kim
Tae-Houn
TH
Roy
Bijoyita
B
Singer
Ruth
R
von Arnim
Albrecht G
AG
Chamovitz
Daniel A
DA
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000378:metabolism; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D014176:Protein Biosynthesis; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; C507061:CONSTITUTIVE PHOTOMORPHOGENIC 9 protein, Arabidopsis; D039621:Eukaryotic Initiation Factor-3; D046988:Proteasome Endopeptidase Complex