Unstructured regions in IRE1α specify BiP-mediated destabilisation of the luminal domain dimer and repression of the UPR.
eLife Sciences Publications Ltd
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Amin-Wetzel, N., Neidhardt, L., Yan, Y., Mayer, M. P., & Ron, D. (2019). Unstructured regions in IRE1α specify BiP-mediated destabilisation of the luminal domain dimer and repression of the UPR.. eLife, 8 https://doi.org/10.7554/elife.50793
Coupling of endoplasmic reticulum stress to dimerisation dependent activation of the UPR transducer IRE1 is incompletely understood. Whilst the luminal co-chaperone ERdj4 promotes a complex between the Hsp70 BiP and IRE1’s stress-sensing luminal domain (IRE1LD) that favours the latter’s monomeric inactive state and loss of ERdj4 de-represses IRE1, evidence linking these cellular and in vitro observations is presently lacking. We report that enforced loading of endogenous BiP onto endogenous IRE1α repressed UPR signalling in CHO cells and deletions in the IRE1α locus that de-repressed the UPR in cells, encode flexible regions of IRE1LD that mediated BiP induced monomerisation in vitro. Changes in the hydrogen exchange mass spectrometry profile of IRE1LD induced by ERdj4 and BiP confirmed monomerisation and were consistent with active destabilisation of the IRE1LD dimer. Together, these observations support a competition model whereby waning ER stress passively partitions ERdj4 and BiP to IRE1LD to initiate active repression of UPR signalling.
CHO Cells, Endoplasmic Reticulum, Animals, Humans, Cricetulus, Escherichia coli, Endoribonucleases, Protein-Serine-Threonine Kinases, Membrane Proteins, Molecular Chaperones, Protein Conformation, Protein Binding, Cricetinae, HSP70 Heat-Shock Proteins, HSP40 Heat-Shock Proteins, Protein Multimerization, Unfolded Protein Response, Endoplasmic Reticulum Stress
Wellcome Trust DeutscheForschungsgemeinschaft
WELLCOME TRUST (200848/Z/16/Z)
External DOI: https://doi.org/10.7554/elife.50793
This record's URL: https://www.repository.cam.ac.uk/handle/1810/300505
Attribution 4.0 International (CC BY)
Licence URL: http://creativecommons.org/licenses/by/4.0/