Crystal structures of GCN2 protein kinase C-terminal domains suggest regulatory differences in yeast and mammals.

Abstract

In response to amino acid starvation, GCN2 phosphorylation of eIF2 leads to repression of general translation and initiation of gene reprogramming that facilitates adaptation to nutrient stress. GCN2 is a multidomain protein with key regulatory domains that directly monitor uncharged tRNAs which accumulate during nutrient limitation, leading to activation of this eIF2 kinase and translational control. A critical feature of regulation of this stress response kinase is its C-terminal domain (CTD). Here, we present high resolution crystal structures of murine and yeast CTDs, which guide a functional analysis of the mammalian GCN2. Despite low sequence identity, both yeast and mammalian CTDs share a core subunit structure and an unusual interdigitated dimeric form, albeit with significant differences. Disruption of the dimeric form of murine CTD led to loss of translational control by GCN2, suggesting that dimerization is critical for function as is true for yeast GCN2. However, although both CTDs bind single- and double-stranded RNA, murine GCN2 does not appear to stably associate with the ribosome, whereas yeast GCN2 does. This finding suggests that there are key regulatory differences between yeast and mammalian CTDs, which is consistent with structural differences.

• Authors: Hongzhen He, Isha Singh, Sheree A Wek, Souvik Dey, Thomas D Baird, Ronald C Wek, Millie M Georgiadis
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 289 Issue 21 Pg. 15023-34 (May 23 2014) ISSN: 1083-351X [Electronic] United States
• PMID: 24719324 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Saccharomyces cerevisiae Proteins
• RNA
• Eif2ak4 protein, mouse
• GCN2 protein, S cerevisiae
• Protein Serine-Threonine Kinases

Topics

• Animals
• Cells, Cultured
• Crystallization
• Crystallography, X-Ray
• Embryo, Mammalian (cytology)
• Fibroblasts (cytology, metabolism)
• Immunoblotting
• Mice
• Mice, Knockout
• Models, Molecular
• Mutation
• Protein Binding
• Protein Biosynthesis (genetics)
• Protein Multimerization
• Protein Serine-Threonine Kinases (chemistry, genetics, metabolism)
• Protein Structure, Tertiary
• RNA (chemistry, genetics, metabolism)
• Saccharomyces cerevisiae (genetics, metabolism)
• Saccharomyces cerevisiae Proteins (chemistry, genetics, metabolism)