AI Article Synopsis
- GCN2 is a kinase that inhibits protein synthesis by phosphorylating eIF2α when it detects uncharged tRNA and stalled ribosomes during stress.
- Researchers explored the structure of GCN2's HisRS-like domain using cryo-electron microscopy (cryoEM), revealing it is adapted for tRNA binding rather than histidine or ATP binding.
- Studies indicate that GCN2's HisRS-like domain functions as a pseudoenzyme, providing new insights into its regulatory mechanisms and overall function.
Article Abstract
GCN2 is a stress response kinase that phosphorylates the translation initiation factor eIF2α to inhibit general protein synthesis when activated by uncharged tRNA and stalled ribosomes. The presence of a HisRS-like domain in GCN2, normally associated with tRNA aminoacylation, led to the hypothesis that eIF2α kinase activity is regulated by the direct binding of this domain to uncharged tRNA. Here we solved the structure of the HisRS-like domain in the context of full-length GCN2 by cryoEM. Structure and function analysis shows the HisRS-like domain of GCN2 has lost histidine and ATP binding but retains tRNA binding abilities. Hydrogen deuterium exchange mass spectrometry, site-directed mutagenesis and computational docking experiments support a tRNA binding model that is partially shifted from that employed by bona fide HisRS enzymes. These results demonstrate that the HisRS-like domain of GCN2 is a pseudoenzyme and advance our understanding of GCN2 regulation and function.
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School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China; State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address:
In this issue of Structure, Yin et al. present the CryoEM structure of the HisRS-like domain of human GCN2 and demonstrate that it is a pseudoenzyme, which binds uncharged tRNA in a different manner than HisRS and does not bind histidine and ATP.
View Article and Find Full Text PDFThe HisRS-like domain of GCN2 is a pseudoenzyme that can bind uncharged tRNA.
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Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada. Electronic address:
Article Synopsis
- GCN2 is a kinase that inhibits protein synthesis by phosphorylating eIF2α when it detects uncharged tRNA and stalled ribosomes during stress.
- Researchers explored the structure of GCN2's HisRS-like domain using cryo-electron microscopy (cryoEM), revealing it is adapted for tRNA binding rather than histidine or ATP binding.
- Studies indicate that GCN2's HisRS-like domain functions as a pseudoenzyme, providing new insights into its regulatory mechanisms and overall function.
Activation of GCN2 by the ribosomal P-stalk.
Proc Natl Acad Sci U S A
March 2019
Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
Cells dynamically adjust their protein translation profile to maintain homeostasis in changing environments. During nutrient stress, the kinase general control nonderepressible 2 (GCN2) phosphorylates translation initiation factor eIF2α, initiating the integrated stress response (ISR). To examine the mechanism of GCN2 activation, we have reconstituted this process in vitro, using purified components.
View Article and Find Full Text PDFThe tRNA-binding moiety in GCN2 contains a dimerization domain that interacts with the kinase domain and is required for tRNA binding and kinase activation.
EMBO J
March 2001
Laboratory of Eukaryotic Gene Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
GCN2 stimulates translation of GCN4 mRNA in amino acid-starved cells by phosphorylating translation initiation factor 2. GCN2 is activated by binding of uncharged tRNA to a domain related to histidyl-tRNA synthetase (HisRS). The HisRS-like region contains two dimerization domains (HisRS-N and HisRS-C) required for GCN2 function in vivo but dispensable for dimerization by full-length GCN2.
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EMBO J
April 2000
Laboratory of Eukaryotic Gene Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Stimulation of GCN4 mRNA translation due to phosphorylation of the alpha-subunit of initiation factor 2 (eIF2) by its specific kinase, GCN2, requires binding of uncharged tRNA to a histidyl-tRNA synthetase (HisRS)-like domain in GCN2. GCN2 function in vivo also requires GCN1 and GCN20, but it was unknown whether these latter proteins act directly to promote the stimulation of GCN2 by uncharged tRNA. We found that the GCN1-GCN20 complex physically interacts with GCN2, binding to the N-terminus of the protein.
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