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Title: Keeping the eIF2 alpha kinase Gcn2 in check

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Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
Grant/Contract Number:
478903/2012-0; 309860/2011-3; 153660/2010-4
Resource Type:
Journal Article: Published Article
Journal Name:
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
Additional Journal Information:
Journal Name: Biochimica et Biophysica Acta (BBA) - Molecular Cell Research; Journal Volume: 1843; Journal Issue: 9; Related Information: CHORUS Timestamp: 2017-06-22 07:30:09; Journal ID: ISSN 0167-4889
Country of Publication:

Citation Formats

Castilho, Beatriz A., Shanmugam, Renuka, Silva, Richard C., Ramesh, Rashmi, Himme, Benjamin M., and Sattlegger, Evelyn. Keeping the eIF2 alpha kinase Gcn2 in check. Netherlands: N. p., 2014. Web. doi:10.1016/j.bbamcr.2014.04.006.
Castilho, Beatriz A., Shanmugam, Renuka, Silva, Richard C., Ramesh, Rashmi, Himme, Benjamin M., & Sattlegger, Evelyn. Keeping the eIF2 alpha kinase Gcn2 in check. Netherlands. doi:10.1016/j.bbamcr.2014.04.006.
Castilho, Beatriz A., Shanmugam, Renuka, Silva, Richard C., Ramesh, Rashmi, Himme, Benjamin M., and Sattlegger, Evelyn. Mon . "Keeping the eIF2 alpha kinase Gcn2 in check". Netherlands. doi:10.1016/j.bbamcr.2014.04.006.
title = {Keeping the eIF2 alpha kinase Gcn2 in check},
author = {Castilho, Beatriz A. and Shanmugam, Renuka and Silva, Richard C. and Ramesh, Rashmi and Himme, Benjamin M. and Sattlegger, Evelyn},
abstractNote = {},
doi = {10.1016/j.bbamcr.2014.04.006},
journal = {Biochimica et Biophysica Acta (BBA) - Molecular Cell Research},
number = 9,
volume = 1843,
place = {Netherlands},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.bbamcr.2014.04.006

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Cited by: 53works
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  • Highlights: •GCN1 is required for mammalian and yeast GCN2 function in a variety of conditions. •Mammalian IMPACT competes with GCN2 for GCN1 binding. •IMPACT and its yeast counterpart YIH1 downregulate GCN1-dependent GCN2 activation. -- Abstract: In response to a range of environmental stresses, phosphorylation of the alpha subunit of the translation initiation factor 2 (eIF2α) represses general protein synthesis coincident with increased translation of specific mRNAs, such as those encoding the transcription activators GCN4 and ATF4. The eIF2α kinase GCN2 is activated by amino acid starvation by a mechanism involving GCN2 binding to an activator protein GCN1, along with associationmore » with uncharged tRNA that accumulates during nutrient deprivation. We previously showed that mammalian IMPACT and its yeast ortholog YIH1 bind to GCN1, thereby preventing GCN1 association with GCN2 and stimulation of this eIF2α kinase during amino acid depletion. GCN2 activity is also enhanced by other stresses, including proteasome inhibition, UV irradiation and lack of glucose. Here, we provide evidence that IMPACT affects directly and specifically the activation of GCN2 under these stress conditions in mammalian cells. We show that activation of mammalian GCN2 requires its interaction with GCN1 and that IMPACT promotes the dissolution of the GCN2–GCN1 complex. To a similar extent as the overexpression of YIH1, overexpression of IMPACT in yeast cells inhibited growth under all stress conditions that require GCN2 and GCN1 for cell survival, including exposure to acetic acid, high levels of NaCl, H{sub 2}O{sub 2} or benomyl. This study extends our understanding of the roles played by GCN1 in GCN2 activation induced by a variety of stress arrangements and suggests that IMPACT and YIH1 use similar mechanisms for regulating this eIF2α kinase.« less
  • The authors have cloned the cDNA of the heme-regulated eIF-2{alpha} kinase (HRI) of rabbit reticulocytes. In vitro translation of mRNA transcribed from the HRI cDNA yields a 90-kDa polypeptide that exhibits eIF-2{alpha} kinase activity and is recognized by a monoclonal antibody directed against authentic HRI. The open reading frame sequence of the HRI cDNA contains all 11 catalytic domains of protein kinases with consensus sequences of protein-serine/threonine kinases in conserved catalytic domains VI and VIII. The HRI cDNA also contains an insert of {approx} 140 amino acids between catalytic domains V and VI. The HRI cDNA coding sequence has extensivemore » homology to GCN2 protein kinase of Saccharomyces cerevisiae and to human double-stranded-RNA-dependent eIF-2{alpha} kinase. This observation suggests that GCN2 protein kinase may be an eIF-2{alpha} kinase in yeast. In addition, HRI has an unusually high degree of homology to three protein kinases (NimA, Wee1, and CDC2) that are involved in the regulation of the cell cycle.« less
  • GCN4 is a transcriptional activator of amino acid-biosynthetic genes in the yeast {ital Saccharomyces cerevisiae}. GCN2, a translational activator of {ital GCN4} expression, contains a domain homologous to the catalytic subunit of eukaryotic protein kinases. Substitution of a highly conserved lysine residue in the kinase domain abolished GCN2 regulatory function in vivo and its ability to autophosphorylate in vitro, indicating that GCN2 acts as a protein kinase in stimulating {ital GCN4} expression. Elevated {ital GCN2} gene dosage led to depression of {ital GCN4} under nonstarvation conditions; however, the authors found that {ital GCN2} mRNA and protein levels did not increasemore » in wild-type cells in response to amino acid starvation. Therefore, it appears that GCN2 protein kinase function is stimulated postranslationally in amino acid-starved cells. Three dominant-constitutive {ital GCN2} point mutations were isolated that led to derepressed {ital GCN4} expression under nonstarvation conditions. Two of the {ital GCN2}(Con) mutations mapped in the kinase domain itself. The third mapped just downstream from a carboxyl-terminal segment homologous to histidyl-tRNA synthetase (HisRS), which the authors suggest might function to detect uncharged tRNA in amino acid-starved cells and activate the adjacent protein kinase moiety.« less
  • M156R, the product of the myxoma virus M156R open reading frame, is a protein of unknown function. However, several homologs of M156R from other viruses are immunomodulatory proteins that bind to interferon-induced protein kinase PKR and inhibit phosphorylation of the eukaryotic translation initiation factor eIF2a. In this study, we have determined the nuclear magnetic resonance (NMR) structure of M156R, the first structure of a myxoma virus protein. The fold consists of a five-stranded antiparallel b-barrel with two of the strands connected by a long loop and a short a-helix. The similarity between M156R and the predicted S1 motif structure ofmore » eIF2a suggests that the viral homologs are pseudosubstrate inhibitors of PKR that mimic eIF2a in order to compete for binding to PKR. A homology modeled structure of the well studied vaccinia virus K3L was generated based on alignment with M156R. Residues important for binding to PKR are conserved residues on the surface of the b-barrel and in the mobile loop, identifying the putative PKR recognition motif.« less