Dynamic Phosphorylation of Yeast eIF4A Drives Changes in Gene Expression that Couple Protein Synthesis with Cell Division

Abstract

The eukaryotic translation initiation factor 4A (eIF4A) supports mRNA recruitment to the ribosomal preinitiation complex through activity of its conserved DEAD‐box RNA helicase motif. Interestingly, in plants eIF4A is differentially phosphorylated near the DEAD motif during various phases of the cell cycle by CDKA, lowering translation activity during mitosis ( Bush et al., 2016). The same Threonine residue of yeast eIF4A (T146) is present in a consensus CDK1/CDKA/Cdc28 motif, and is highly phosphorylated in large‐scale studies ( Soulard et al., 2010). To further dissect the molecular function of eIF4A, we are analyzing specific in vitro and in vivo changes that take place due to phosphorylation of eIF4A under normal conditions and in response to stress. We have mutated eIF4A residue T146 to phosphodeficient (Ala) and phosphomimetic (Glu, Asp) forms, and analyzed the effects of these mutations on growth and translation. Our data indicate that the phosphorylation status of eIF4A sensitizes yeast cells to membrane stressors in a manner affected by eIF4A•eIF4B coupling, and that constitutive phosphorylation of this residue is lethal due to arrest prior to cell division. Mechanistically, phosphorylation disrupts RNA binding by eIF4A. Together our results suggest that dynamic phosphorylation of eIF4A modulates translation changes that promote cell division and resistance to external stressors. Support or Funding Information This work was supported by NIH grant R00GM119173 and startup funds from SUNY at Buffalo‐College of Arts and Sciences A.SoulardA.CremonesiS.MoesF.SchützP.JenöM. N.HallMolecular biology of the cell211934753486C. P.AlbuquerqueH.ZhouMolecular & Cellular Proteomics7713891396A. O.HelbigS.RosatiP. W.PijnappelB.van BreukelenM. H.TimmersS.MohammedA. J.HeckBMC genomics111685M. S.BushO.PierratC.NibauV.MikitovaT.ZhengF. M.CorkeJ. H.DoonanPlant physiology1721128140F.ZhouS. E.WalkerS. F.MitchellJ. R.LorschA. G.HinnebuschJBC289317041722