8tqo
Eukaryotic translation initiation factor 2B tetramer
Structural highlights
DiseaseEI2BE_HUMAN Defects in EIF2B5 are a cause of leukodystrophy with vanishing white matter (VWM) [MIM:603896. VWM is a leukodystrophy that occurs mainly in children. Neurological signs include progressive cerebellar ataxia, spasticity, inconstant optic atrophy and relatively preserved mental abilities. The disease is chronic-progressive with, in most individuals, additional episodes of rapid deterioration following febrile infections or minor head trauma. While childhood onset is the most common form of the disorder, some severe forms are apparent at birth. A severe, early-onset form seen among the Cree and Chippewayan populations of Quebec and Manitoba is called Cree leukoencephalopathy. Milder forms may not become evident until adolescence or adulthood. Some females with milder forms of the disease who survive to adolescence exhibit ovarian dysfunction. This variant of the disorder is called ovarioleukodystrophy.[1] [2] [3] [4] [5] [6] FunctionEI2BE_HUMAN Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. Publication Abstract from PubMedThe integrated stress response (ISR) enables cells to survive a variety of acute stresses, but chronic activation of the ISR underlies age-related diseases. ISR signaling downregulates translation and activates expression of stress-responsive factors that promote return to homeostasis and is initiated by inhibition of the decameric guanine nucleotide exchange factor eIF2B. Conformational and assembly transitions regulate eIF2B activity, but the allosteric mechanisms controlling these dynamic transitions and mediating the therapeutic effects of the small-molecule ISR inhibitor ISRIB are unknown. Using hydrogen-deuterium exchange-mass spectrometry and cryo-electron microscopy, we identified a central alpha-helix whose orientation allosterically coordinates eIF2B conformation and assembly. Biochemical and cellular signaling assays show that this 'switch-helix' controls eIF2B activity and signaling. In sum, the switch-helix acts as a fulcrum of eIF2B conformational regulation and is a highly conserved actuator of ISR signal transduction. This work uncovers a conserved allosteric mechanism and unlocks new therapeutic possibilities for ISR-linked diseases. A helical fulcrum in eIF2B coordinates allosteric regulation of stress signaling.,Lawrence RE, Shoemaker SR, Deal A, Sangwan S, Anand AA, Wang L, Marqusee S, Walter P Nat Chem Biol. 2024 Apr;20(4):422-431. doi: 10.1038/s41589-023-01453-9. Epub 2023 , Nov 9. PMID:37945896[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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