Abstract
The 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 α-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. (Figure presented.)
Original language | English (US) |
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Pages (from-to) | 422-431 |
Number of pages | 10 |
Journal | Nature Chemical Biology |
Volume | 20 |
Issue number | 4 |
DOIs | |
State | Published - Apr 2024 |
Funding
We thank M. Boone, M. Schoof and the Walter and Marqusee labs for helpful discussions throughout the course of this project; J. Lindner for preliminary optimization of eIF2B HDX\u2013MS coverage; Calico for the generous gift of purified eIF2 heterotrimer; A. Frost for critical reading of the manuscript and Z. Yu and D. Bulkley of the UCSF Center for Advanced Cryo-EM facility, which is supported by NIH grants S10OD021741 and S10OD020054 and the Howard Hughes Medical Institute. We also thank the QB3 shared cluster for computational support. This work was supported by generous support from Calico Life Sciences (to P.W.), a generous gift from The George and Judy Marcus Family Foundation (to P.W.), the Jane Coffin Child Foundation Postdoctoral Fellowship (to R.E.L.), Helen Hay Whitney Postdoctoral fellowship and 1K99GM143527 (to S.S.) and the Damon Runyon Cancer Research Foundation Postdoctoral fellowship (to L.W.). S.M. is supported by the Chan Zuckerburg Bi-Hub, NIH grant GM050945 and NIH grant R35GM149319. P.W. was an investigator with the Howard Hughes Medical Institute.
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology