Present address: Genome Institute of Singapore, 60 Biopolis Street, Singapore 138672, Singapore.
Selective recruitment of proteins to 5′ cap complexes during the growth cycle in Arabidopsis
Article first published online: 7 MAY 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 59, Issue 3, pages 400–412, August 2009
How to Cite
Bush, M. S., Hutchins, A. P., Jones, A. M.E., Naldrett, M. J., Jarmolowski, A., Lloyd, C. W. and Doonan, J. H. (2009), Selective recruitment of proteins to 5′ cap complexes during the growth cycle in Arabidopsis. The Plant Journal, 59: 400–412. doi: 10.1111/j.1365-313X.2009.03882.x
- Issue published online: 24 JUL 2009
- Article first published online: 7 MAY 2009
- Received 19 January 2009; revised 6 March 2009; accepted 10 March 2009. published online 7 May 2009.
- cap complex;
- translation initiation factor;
- growth cycle;
Translation of most mRNAs is performed in a cap-dependent manner, requiring a protein complex, the cap complex, to regulate the accessibility of the message to the 40S ribosome. The cap complex initiates protein translation by binding to the 5′ cap of an mRNA and recruiting ribosomes to begin translation. Compared to animals and yeast, there are significant plant-specific differences in the regulation of cap-dependent mRNA translation, but these are poorly understood. Here, we purified proteins that bind to the 5′ cap during the Arabidopsis growth cycle. The protein profile of the cap-binding complexes varies during the various stages of the growth cycle in suspension culture cells. Using Western blotting, the cap complexes of quiescent cells were found to be composed of only three major proteins: eIF4isoE, which is primarily a cytoplasmic protein, and eIF4E and CBP80, which accumulate in the nucleus. However, when cells proliferate, at least 10 major proteins bind directly or indirectly to the 5′ cap. Proteomic, Western blotting and immunoprecipitation data establish that the spectrum of RNA helicases in the cap complexes also changes during the growth cycle. Cap complexes from proliferating cultures mainly contain eIF4A, which associates with at least four cap complexes, but eIF4A is replaced by additional helicases in quiescent cells. These findings suggest that the dynamic and selective recruitment of various proteins to mRNA 5′ cap complexes could play an important role in the regulation of gene expression.