UNASSIGNED: Cells respond to changes in their environment through mechanisms that often necessitate reprogramming of the translation machinery. The fastest and strongest of all tested responses is the translation inhibition observed following abrupt depletion of @entity413 from the media of @entity375 cells. The speed of the response suggests a post-translational modification of a key component of the translation machinery. This translation factor is as yet unknown. A @entity268 -dependent protein kinase mutant @entity375 ( @entity33962 (w) ) that does not respond properly to @entity413 depletion and maintains translation was described previously. We hypothesized that the inability of @entity33962 (w) to arrest translation results from abnormal expression of key translation mediators. Genome-wide analysis of steady-state mRNA levels in @entity33962 (w) revealed underexpression of several candidates. Elevating the cellular levels of eukaryotic initiation factor (eIF) 5 by overexpression rescued the translational defect of @entity33962 (w) . Restoring ribosomal dissociation by eIF5 necessitated an active GAP domain and multiple regions throughout this protein. Phosphoproteomics analysis of wild-type cells overexpressing eIF5 revealed increased phosphorylation in a novel site (Thr191) upon @entity413 depletion. Mutating this residue and introducing it into @entity33962 (w) abolished the ability of eIF5 to rescue the translational defect. Intriguingly, introducing this mutation into the wild-type strain did not hamper its translational response. We further show that Thr191 is phosphorylated in  vitro by Casein Kinase II (CKII), and @entity375 cells with a mutated CKII have a reduced response to @entity413 depletion. These results implicate phosphorylation of eIF5 at Thr191 by CKII as one of the pathways for regulating translation upon @entity413 depletion.

Overexpression of eukaryotic initiation factor 5 rescues the translational defect of XXXX (w) in a manner that necessitates a novel phosphorylation site.

@entity268 :: ('CHEBI:17489', 'Chemical') :: ['cAMP'] @entity375 :: ('4932', 'Species') :: ['yeast strain', 'yeast'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose'] @entity33962 :: ('853275(Tax:4932)', 'Gene') :: ['tpk1']
@entity33962 :: (853275(Tax:4932),Gene) :: ['tpk1']
