Intrinsic Structural Features of the Human IRE1α Transmembrane Domain Sense Membrane Lipid Saturation
Abstract
Activation of inositol-requiring enzyme (IRE1α) is an indispensable step in remedying the cellular stress associated with lipid perturbation in the endoplasmic reticulum (ER) membrane. IRE1α is a single-spanning ER transmembrane protein possessing both kinase and endonuclease functions, and its activation can be fully achieved through the dimerization and/or oligomerization process. How IRE1α senses membrane lipid saturation remains largely unresolved. Using both computational and experimental tools, we systematically investigated the dimerization process of the transmembrane domain (TMD) of IRE1α and found that, with help of the serine 450 residue, the conserved tryptophan 457 residue buttresses the core dimerization interface of IRE1α-TMD. BiFC (bimolecular fluorescence complementation) experiments revealed that mutation on these residues abolished the saturated fatty acid-induced dimerization in the ER membrane and subsequently inactivated IRE1α activity in vivo. Therefore, our results suggest that the structural elements of IRE1α-TMD serve as a key sensor that detects membrane aberrancy.
Additional Information
© 2019 The Author(s). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Received 3 August 2018, Revised 22 January 2019, Accepted 5 March 2019, Available online 2 April 2019. We thank Dr. Heedeok Hong for valuable discussions on the parallax method. This study was supported in part by the National Science Foundation (CBET 1510895, CBET 1547518, and CBET 1802992) and the NIH (R01GM079688, R01GM089866, and R21CA176854). Author Contributions: Conceptualization, H.C., A.K.S., and C.C.; Experiments, H.C., A.O., G.H.K., and S.Y.; MD Simulations, F.S.; Data Analysis, H.C., F.S., A.O., G.H.K., L.Q., and C.C.; Manuscript Writing, H.C., F.S., and A.O.; Manuscript Editing, H.C., A.K.S., and C.C. (with all authors' input); Funding Acquisition, C.C. and A.K.S. The authors declare no competing interests.Attached Files
Published - 1-s2.0-S2211124719303249-main.pdf
Accepted Version - nihms-1526212.pdf
Supplemental Material - 1-s2.0-S2211124719303249-mmc1.pdf
Supplemental Material - 1-s2.0-S2211124719303249-mmc2.xlsx
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Additional details
- PMCID
- PMC6467502
- Eprint ID
- 94361
- Resolver ID
- CaltechAUTHORS:20190402-102705083
- CBET-1510895
- NSF
- CBET-1547518
- NSF
- CBET-1802992
- NSF
- R01GM079688
- NIH
- R01GM089866
- NIH
- R21CA176854
- NIH
- Created
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2019-04-02Created from EPrint's datestamp field
- Updated
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2022-03-01Created from EPrint's last_modified field