WNK1 is an assembly factor for the human ER membrane protein complex
Abstract
The assembly of nascent proteins into multi-subunit complexes is a tightly regulated process that must occur at high fidelity to maintain cellular homeostasis. The ER membrane protein complex (EMC) is an essential insertase that requires seven membrane-spanning and two soluble cytosolic subunits to function. Here, we show that the kinase with no lysine 1 (WNK1), known for its role in hypertension and neuropathy, functions as an assembly factor for the human EMC. WNK1 uses a conserved amphipathic helix to stabilize the soluble subunit, EMC2, by binding to the EMC2–8 interface. Shielding this hydrophobic surface prevents promiscuous interactions of unassembled EMC2 and directly competes for binding of E3 ubiquitin ligases, permitting assembly. Depletion of WNK1 thus destabilizes both the EMC and its membrane protein clients. This work describes an unexpected role for WNK1 in protein biogenesis and defines the general requirements of an assembly factor that will apply across the proteome.
Additional Information
© 2021 Elsevier Inc. Received 10 July 2020, Revised 2 March 2021, Accepted 14 April 2021, Available online 7 May 2021. We thank Christian Schlieker for reagents and John O'Neill, Ramanujan Hegde, Henry Lester, and the Voorhees lab for thoughtful discussions. Confocal imaging was performed in the Caltech Biological Imaging Facility with the support of the Caltech Beckman Institute and the Arnold and Mabel Beckman Foundation. Flow cytometry was performed at the Caltech Flow Cytometry Facility. This work was supported by the Heritage Medical Research Institute, the Kinship Foundation, the Pew-Stewart Foundation, and the National Institute of General Medical Sciences of the National Institutes of Health under award no. DP2GM137412. T.P. is supported by a postdoctoral fellowship from the Deutsche Forschungsgemeinschaft and received prior funding from a Caltech Ross fellowship. Author contributions: T.P., A.G., and R.M.V. conceived the study. T.P., R.S.O., G.P.T., and M.H. performed the experiments. T.P., R.M.V., M.H., K.J., G.P.T., M.J.S., and A.M. analyzed all of the biochemical data. T.P., M.H., and R.M.V. wrote the manuscript with input from all of the authors. The authors declare no competing interests. Inclusion and diversity: One or more of the authors of this paper self-identifies as an underrepresented ethnic minority in science.Attached Files
Accepted Version - nihms-1697207.pdf
Submitted - 2020.07.20.213066v1.full.pdf
Supplemental Material - 1-s2.0-S109727652100318X-mmc1.pdf
Supplemental Material - 1-s2.0-S109727652100318X-mmc2.xlsx
Files
Additional details
- Alternative title
- Regulated assembly of the ER membrane protein complex
- PMCID
- PMC8254792
- Eprint ID
- 104508
- Resolver ID
- CaltechAUTHORS:20200722-105320999
- Caltech Beckman Institute
- Arnold and Mabel Beckman Foundation
- Heritage Medical Research Institute
- Kinship Foundation
- Pew-Stewart Foundation
- DP2GM137412
- NIH
- Deutsche Forschungsgemeinschaft (DFG)
- Caltech Ross Fellowship
- Created
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2020-07-22Created from EPrint's datestamp field
- Updated
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2022-07-12Created from EPrint's last_modified field
- Caltech groups
- Heritage Medical Research Institute, Division of Biology and Biological Engineering