Fiona Shilliday,Miguel Gancedo-Rodrigo,Ginto George,Shintaro Aibara,Santosh Adhikari,Syedah Neha Ashraf,Evelyne J Barrey,Paolo A Centrella,Damian Crowther,Paige Dickson,Diana Gikunju,Marie-Aude Guié,John P Guilinger,Anders Gunnarsson,Heather P Harding,Christopher D Hupp,Rachael Jetson,Anthony D Keefe,JeeSoo Monica Kim,Richard J Lewis,Taiana Maia de Oliveira,Jennifer Le-Marshall,Usha Narayanan,Katherine A Nugai,Dušan Petrović,Emma Rivers,David Ron,Daisy Stringfellow,Karl Syson,Lewis Ward,John T S Yeoman,Yan Yu,Ying Zhang,Alisa Zyryanova,David J Baker,Perla Breccia,John E Linley

Nature Communications

DOI: 10.1038/s41467-026-72688-y

Abstract

Eukaryotic initiation factor 2B (eIF2B), a guanine nucleotide exchange factor (GEF), promotes protein synthesis by charging translation initiation factor 2 (eIF2) with GTP. Stress-induced phosphorylation of eIF2 on its α-subunit [eIF2(αP)] inhibits this reaction triggering a protective Integrated Stress Response (ISR). A DNA-encoded chemical library (DEL) screen for modulators of eIF2B, led to the identification of a chemical series that stabilises the inactive state of eIF2B, stimulating the ISR. Cryo-EM of compound-bound eIF2B reveals a conformational switch to the inactive state engaged by eIF2(αP). In cells, compound activity is sensitive to eIF2's phosphorylation state and to a competing eIF2B ligand (ISRIB) that activates the GEF allosterically. These findings establish the feasibility of targeting eIF2B with a drug-like allosteric inhibitor, that serves as an ISR activator (ISRAC), paving the way to explore the therapeutic potential of eIF2B-directed ISR activation.