title: Residues required for phosphorylation of translation initiation factor eIF2α under diverse stress conditions are divergent between yeast and human.
abstract: PERK, PKR, HRI and GCN2 are the four mammalian kinases that phosphorylate the α subunit of the eukaryotic translation initiation factor 2 (eIF2α) on Ser51. This phosphorylation event is conserved among many species and attenuates protein synthesis in response to diverse stress conditions. In contrast, Saccharmyces cerevisiae expresses only the GCN2 kinase. It was demonstrated previously in S. cerevisiae that single point mutations in eIF2α's N-terminus severely impaired phosphorylation at Ser51. To assess whether similar recognition patterns are present in mammalian eIF2α, we expressed human eIF2α's with these mutations in mouse embryonic fibroblasts and assessed their phosphorylation under diverse stress conditions. Some of the mutations prevented the stress-induced phosphorylation of eIF2α by all mammalian kinases, thus defining amino acid residues in eIF2α (Gly 30, Leu 50, and Asp 83) that are required for substrate recognition. We also identified residues that were less critical or not required for recognition by the mammalian kinases (Ala 31, Met 44, Lys 79, and Tyr 81), even though they were essential for recognition of the yeast eIF2α by GCN2. We propose that mammalian eIF2α kinases evolved to maximize their interactions with the evolutionarily conserved Ser51 residue of eIF2α in response to diverse stress conditions, thus adding to the complex signaling pathways that mammalian cells have over simpler organisms.
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Mithu
authors.initials: M
authors.lastname: Majumder
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Mitchell
authors.affiliation: Virogene Technology, 11000 Cedar Ave., Cleveland, OH, United States.
authors.forename: Sergei
authors.initials: S
authors.lastname: Merkulov
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Bo-Jhih
authors.initials: BJ
authors.lastname: Guan
authors.affiliation: Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Snider
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States.
authors.forename: Dawid
authors.initials: D
authors.lastname: Krokowski
authors.affiliation: Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States. Electronic address: vivien.yee@case.edu.
authors.forename: Vivien C
authors.initials: VC
authors.lastname: Yee
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States. Electronic address: maria.hatzoglou@case.edu.
authors.forename: Maria
authors.initials: M
authors.lastname: Hatzoglou
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D006982:Hypertonic Solutions / Q000494:pharmacology; D051379:Mice; D008958:Models, Molecular; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011070:Poly I-C / Q000494:pharmacology; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; D015852:Eukaryotic Initiation Factor-2; D006982:Hypertonic Solutions; D050505:Mutant Proteins; D011070:Poly I-C
keywords: Protein kinases; Stress response; Translation initiation; Translational control