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Plant Physiol. 2016 Sep;172(1):128-40. doi: 10.1104/pp.16.00435. Epub 2016 Jul 7.

eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and Is Modulated by Phosphorylation.

Author information

1
Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.S.B., O.P., V.M.);Institute of Biological, Environmental, and Rural Sciences, Aberystwyth University, Gogerddan Campus, Aberystwyth SY23 3EE, United Kingdom (C.N., F.M.K.C., K.V., J.H.D.);Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Science, Hangzhou City, Zhejiang Province 310021, China (T.Z.);Aristotle University of Thessaloniki, Faculty of Science, School of Biology, Department of Botany, 54124 Thessaloniki, Greece (K.V.); andDepartment of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712 (L.K.M., K.S.B.).
2
Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom (M.S.B., O.P., V.M.);Institute of Biological, Environmental, and Rural Sciences, Aberystwyth University, Gogerddan Campus, Aberystwyth SY23 3EE, United Kingdom (C.N., F.M.K.C., K.V., J.H.D.);Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Science, Hangzhou City, Zhejiang Province 310021, China (T.Z.);Aristotle University of Thessaloniki, Faculty of Science, School of Biology, Department of Botany, 54124 Thessaloniki, Greece (K.V.); andDepartment of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712 (L.K.M., K.S.B.) kbrowning@cm.utexas.edu john.doonan@aber.ac.uk.

Abstract

Eukaryotic initiation factor 4A (eIF4A) is a highly conserved RNA-stimulated ATPase and helicase involved in the initiation of messenger RNA translation. Previously, we found that eIF4A interacts with cyclin-dependent kinase A (CDKA), the plant ortholog of mammalian CDK1. Here, we show that this interaction occurs only in proliferating cells where the two proteins coassociate with 5'-cap-binding protein complexes, eIF4F or the plant-specific eIFiso4F. CDKA phosphorylates eIF4A on a conserved threonine residue (threonine-164) within the RNA-binding motif 1b TPGR. In vivo, a phospho-null (APGR) variant of the Arabidopsis (Arabidopsis thaliana) eIF4A1 protein retains the ability to functionally complement a mutant (eif4a1) plant line lacking eIF4A1, whereas a phosphomimetic (EPGR) variant fails to complement. The phospho-null variant (APGR) rescues the slow growth rate of roots and rosettes, together with the ovule-abortion and late-flowering phenotypes. In vitro, wild-type recombinant eIF4A1 and its phospho-null variant both support translation in cell-free wheat germ extracts dependent upon eIF4A, but the phosphomimetic variant does not support translation and also was deficient in ATP hydrolysis and helicase activity. These observations suggest a mechanism whereby CDK phosphorylation has the potential to down-regulate eIF4A activity and thereby affect translation.

PMID:
27388680
PMCID:
PMC5074640
DOI:
10.1104/pp.16.00435
[Indexed for MEDLINE]
Free PMC Article

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