Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation

doi:10.1111/j.1365-313X.2007.03347.x

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Wiley InterScience

The Plant Journal

Volume 53 Issue 2, Pages 300 - 311

Published Online: 17 Oct 2007

Published in association with the Society for Experimental Biology

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Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation

Avital Yahalom ¹ , Tae-Houn Kim ^2,† , Bijoyita Roy ² , Ruth Singer ¹ , Albrecht G. von Arnim ² and Daniel A. Chamovitz ^1,*

¹ Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel , and ² Department of Biochemistry Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN 37996, USA

Correspondence to *(fax +972 3 6408989; e-mail dannyc@ex.tau.ac.il).

^† Present address: Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA.

KEYWORDS

COP9 signalosome • eIF3 • Int-6/Int6 • protein translation

ABSTRACT

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.

Received 1 August 2007; revised 21 September 2007; accepted 27 September 2007

DIGITAL OBJECT IDENTIFIER (DOI)

10.1111/j.1365-313X.2007.03347.x About DOI