A molecular stabiliser of an inhibitory eIF2B-eIF2(αP) complex activates the Integrated Stress Response

Silliday, F.; Gancedo-Rodrigo, M.; George, G.; Adhikari, S.; Ashraf, S. N.; Barrey, E. J.; Centrella, P. A.; Crowther, D.; Dickson, P.; Gikunju, D.; Guie, M.-A.; Guilinger, J. P.; Gunnarsson, A.; Harding, H. P.; Hupp, C. D.; Jetson, R.; Keefe, A. D.; Kim, J. M.; Lewis, R. J.; de Oliveira, T. M.; Le-Marshall, J.; Narayanan, U.; Nugai, K. A.; Pertovic, D.; Rivers, E.; Ron, D.; Stringfellow, D.; Syson, K.; Ward, L.; Yeoman, J. T.; Yu, Y.; Zhang, Y.; Zyryanova, A.; Baker, D. J.; Breccia, P.; Linley, J.

doi:10.1101/2025.09.25.678332

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bioRxiv · 10.1101/2025.09.25.678332

A molecular stabiliser of an inhibitory eIF2B-eIF2(αP) complex activates the Integrated Stress Response

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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 -subunit [eIF2(P)] 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 inactivates eIF2B, stimulating the ISR. Cryo-EM of compound-bound eIF2B revealed a conformational switch to the inactive state engaged by eIF2(P). In cells, compound activity was sensitive to eIF2s phosphorylation state and to a competing eIF2B ligand (ISRIB) that activates the GEF allosterically. These findings mark the discovery of a first-in-class drug-like allosteric inhibitor of eIF2B, an ISR activator (ISRAC), paving the way to explore the therapeutic potential of eIF2B-directed ISR activation.

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Silliday, F., Gancedo-Rodrigo, M., George, G., Adhikari, S., Ashraf, S. N., Barrey, E. J., Centrella, P. A., Crowther, D., Dickson, P., Gikunju, D., Guie, M.-A., Guilinger, J. P., Gunnarsson, A., Harding, H. P., Hupp, C. D., Jetson, R., Keefe, A. D., Kim, J. M., Lewis, R. J., de Oliveira, T. M., Le-Marshall, J., Narayanan, U., Nugai, K. A., Pertovic, D., Rivers, E., Ron, D., Stringfellow, D., Syson, K., Ward, L., Yeoman, J. T., Yu, Y., Zhang, Y., Zyryanova, A., Baker, D. J., Breccia, P., Linley, J.. 2025-09-26. A molecular stabiliser of an inhibitory eIF2B-eIF2(αP) complex activates the Integrated Stress Response. https://doi.org/10.1101/2025.09.25.678332

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