Publication Date:
2016-02-24
Description:
Eukaryotic cells restrict protein synthesis under various stress conditions, by inhibiting the eukaryotic translation initiation factor 2B (eIF2B). eIF2B is the guanine nucleotide exchange factor for eIF2, a heterotrimeric G protein consisting of alpha-, beta- and gamma-subunits. eIF2B exchanges GDP for GTP on the gamma-subunit of eIF2 (eIF2gamma), and is inhibited by stress-induced phosphorylation of eIF2alpha. eIF2B is a heterodecameric complex of two copies each of the alpha-, beta-, gamma-, delta- and epsilon-subunits; its alpha-, beta- and delta-subunits constitute the regulatory subcomplex, while the gamma- and epsilon-subunits form the catalytic subcomplex. The three-dimensional structure of the entire eIF2B complex has not been determined. Here we present the crystal structure of Schizosaccharomyces pombe eIF2B with an unprecedented subunit arrangement, in which the alpha2beta2delta2 hexameric regulatory subcomplex binds two gammaepsilon dimeric catalytic subcomplexes on its opposite sides. A structure-based in vitro analysis by a surface-scanning site-directed photo-cross-linking method identified the eIF2alpha-binding and eIF2gamma-binding interfaces, located far apart on the regulatory and catalytic subcomplexes, respectively. The eIF2gamma-binding interface is located close to the conserved 'NF motif', which is important for nucleotide exchange. A structural model was constructed for the complex of eIF2B with phosphorylated eIF2alpha, which binds to eIF2B more strongly than the unphosphorylated form. These results indicate that the eIF2alpha phosphorylation generates the 'nonproductive' eIF2-eIF2B complex, which prevents nucleotide exchange on eIF2gamma, and thus provide a structural framework for the eIF2B-mediated mechanism of stress-induced translational control.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kashiwagi, Kazuhiro -- Takahashi, Mari -- Nishimoto, Madoka -- Hiyama, Takuya B -- Higo, Toshiaki -- Umehara, Takashi -- Sakamoto, Kensaku -- Ito, Takuhiro -- Yokoyama, Shigeyuki -- England -- Nature. 2016 Mar 3;531(7592):122-5. doi: 10.1038/nature16991. Epub 2016 Feb 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. ; RIKEN Systems and Structural Biology Center, Tsurumi-ku, Yokohama 230-0045, Japan. ; RIKEN Center for Life Science Technologies, Tsurumi-ku, Yokohama 230-0045, Japan. ; RIKEN Structural Biology Laboratory, Tsurumi-ku, Yokohama 230-0045, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26901872" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Motifs
;
Binding Sites
;
Biocatalysis
;
Cross-Linking Reagents/chemistry
;
Crystallography, X-Ray
;
Eukaryotic Initiation Factor-2B/*chemistry/metabolism
;
Guanosine Diphosphate/metabolism
;
Guanosine Triphosphate/metabolism
;
Models, Molecular
;
Phosphorylation
;
Protein Binding
;
Protein Biosynthesis
;
Protein Structure, Quaternary
;
Protein Subunits/chemistry/metabolism
;
Schizosaccharomyces/*chemistry
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
