The stress-sensing domain of activated IRE1α forms helical filaments in narrow ER membrane tubes
Abstract
The signaling network of the unfolded protein response (UPR) adjusts the protein-folding capacity of the endoplasmic reticulum (ER) according to need. The most conserved UPR sensor, IRE1α, spans the ER membrane and activates through oligomerization. IRE1α oligomers accumulate in dynamic foci. We determined the in situ structure of IRE1α foci by cryogenic correlated light and electron microscopy combined with electron cryo-tomography and complementary immuno–electron microscopy in mammalian cell lines. IRE1α foci localized to a network of narrow anastomosing ER tubes (diameter, ~28 nm) with complex branching. The lumen of the tubes contained protein filaments, which were likely composed of arrays of IRE1α lumenal domain dimers that were arranged in two intertwined, left-handed helices. This specialized ER subdomain may play a role in modulating IRE1α signaling.
Additional Information
© 2021 American Association for the Advancement of Science. Received 24 February 2021; accepted 11 August 2021. We thank E. Karagoz, S. Niekamp, V. Belyy, M. Elvekrog, D. Acosta-Alvear, R. Fetter, and S. van Dijk for their advice and technical assistance and G. Huber, R. Ernst, A. Frost, and J. Nunnari for insightful discussions. This work was supported in part by NWO NEMI (grant 184.034.014 to J.K.) and the NIH (grants P50 AI150464 and R35 GM122588 to G.J.J. and R01-GM032384 to P.W.). N.-H.T. is supported by the NSF GRFP. P.W. is an Investigator of the Howard Hughes Medical Institute. Author contributions: Methodology: N.-H.T., S.D.C., A.D.M.; Formal analysis: N.-H.T., S.D.C., A.D.M. Visualization: N.-H.T., S.D.C.; Writing – original draft & editing: N.-H.T., S.D.C.; Conceptualization: A.A., J.K., P.W., G.J.J.; Resources: A.A., J.K., P.W., G.J.J.; Supervision: A.A., J.K., P.W., G.J.J.; Funding acquisition: A.A., J.K., P.W., G.J.J.; Writing – review & editing: P.W., G.J.J. Competing interests: A.D.M. received a salary from Genentech, Inc. The authors declare no other competing interests. Data and materials availability: The codes used for analyses are available through Zenodo (38). The subtomogram-averaged maps can be accessed at EMDB (EMD-23058). Raw and processed data, cell lines, and reagents are available upon request.Attached Files
Submitted - 2021.02.24.432779v1.full.pdf
Supplemental Material - science.abh2474_mdar_reproducibility_checklist.pdf
Supplemental Material - science.abh2474_movies_s1_to_s3.zip
Supplemental Material - science.abh2474_sm.pdf
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Additional details
- Eprint ID
- 108215
- Resolver ID
- CaltechAUTHORS:20210225-141123693
- 184.034.014
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
- P50 AI150464
- NIH
- R35 GM122588
- NIH
- R01-GM032384
- NIH
- NSF Graduate Research Fellowship
- Howard Hughes Medical Institute (HHMI)
- Created
-
2021-02-26Created from EPrint's datestamp field
- Updated
-
2021-10-04Created from EPrint's last_modified field
- Caltech groups
- Division of Biology and Biological Engineering