title: Protein kinase CK2 potentiates translation efficiency by phosphorylating eIF3j at Ser127.
abstract: In eukaryotic protein synthesis the translation initiation factor 3 (eIF3) is a key player in the recruitment and assembly of the translation initiation machinery. Mammalian eIF3 consists of 13 subunits, including the loosely associated eIF3j subunit that plays a stabilizing role in the eIF3 complex formation and interaction with the 40S ribosomal subunit. By means of both co-immunoprecipitation and mass spectrometry analyses we demonstrate that the protein kinase CK2 interacts with and phosphorylates eIF3j at Ser127. Inhibition of CK2 activity by CX-4945 or down-regulation of the expression of CK2 catalytic subunit by siRNA cause the dissociation of j-subunit from the eIF3 complex as judged from glycerol gradient sedimentation. This finding proves that CK2-phosphorylation of eIF3j is a prerequisite for its association with the eIF3 complex. Expression of Ser127Ala-eIF3j mutant impairs both the interaction of mutated j-subunit with the other eIF3 subunits and the overall protein synthesis. Taken together our data demonstrate that CK2-phosphorylation of eIF3j at Ser127 promotes the assembly of the eIF3 complex, a crucial step in the activation of the translation initiation machinery.
authors.affiliation: Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Borgo
authors.affiliation: Proteomic Center of Padova University, Via G. Orus B2, 35129 Padova, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Franchin
authors.affiliation: Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Salizzato
authors.affiliation: Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cesaro
authors.affiliation: Proteomic Center of Padova University, Via G. Orus B2, 35129 Padova, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Arrigoni
authors.affiliation: Venitian Institute of Oncology (IOV-IRCCS), Via Gattamelata 64, 35128 Padova, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Matricardi
authors.affiliation: Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy.
authors.forename: Lorenzo A
authors.initials: LA
authors.lastname: Pinna
authors.affiliation: Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy. Electronic address: arianna.donella@unipd.it.
authors.forename: Arianna
authors.initials: A
authors.lastname: Donella-Deana
mesh_terms: D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D020868:Gene Silencing / Q000187:drug effects; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D009154:Mutation / Q000235:genetics; D009287:Naphthyridines / Q000494:pharmacology; D010619:Phenazines; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism; D013379:Substrate Specificity / Q000187:drug effects
chemical_list: D039621:Eukaryotic Initiation Factor-3; D009287:Naphthyridines; D010619:Phenazines; D021122:Protein Subunits; D010768:Phosphoserine; C555142:silmitasertib; D047390:Casein Kinase II
keywords: Protein kinase CK2; Translation initiation activation; eIF3 assembly; eIF3 complex; eIF3j phosphorylation