Conformational dynamics of auto-inhibition in the ER calcium sensor STIM1
- Stanford University School of Medicine, United States
- West Virginia University School of Medicine, United States
- Stanford University School of Medicine, Howard Hughes Medical Institute, United States
Abstract
The dimeric ER Ca2+ sensor STIM1 controls store-operated Ca2+ entry (SOCE) through the regulated binding of its CRAC activation domain (CAD) to Orai channels in the plasma membrane. In resting cells, the STIM1 CC1 domain interacts with CAD to suppress SOCE, but the structural basis of this interaction is unclear. Using single-molecule Förster resonance energy transfer (smFRET) and protein crosslinking approaches, we show that CC1 interacts dynamically with CAD in a domain-swapped configuration with an orientation predicted to sequester its Orai-binding region adjacent to the ER membrane. Following ER Ca2+ depletion and release from CAD, cysteine crosslinking indicates that the two CC1 domains become closely paired along their entire length in the active Orai-bound state. These findings provide a structural basis for the dual roles of CC1: sequestering CAD to suppress SOCE in resting cells and propelling it towards the plasma membrane to activate Orai and SOCE after store depletion.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files; Source Data files have been provided for Figure 1 - figure supplement 1-3, Figure 2 - figure supplement 1, Figure 3 - figure supplement 1, Figure 4 - figure supplement 1, Figure 5 - figure supplement 1, Figure 5 - figure supplement 2, Figure 5 - figure supplement 3, Figure 7, Figure 7 - figure supplement 1, and Figure 7 - figure supplement 2.Custom code used to analyze smFRET data is available at https://github.com/vandorp/stim1_paper
Article and author information
Author details
Funding
National Institutes of Health (R37GM45374)
- Richard S Lewis
Mathers Charitable Foundation
- Richard S Lewis
Stanford University (Discovery Innovation Award)
- Richard S Lewis
National Institutes of Health (R37MH63105)
- Axel T Brunger
Dutch Research Council NWO (Rubicon postdoctoral fellowship 825.13.027)
- Stijn van Dorp
American Heart Association (postdoctoral fellowship 16POST30780015)
- Stijn van Dorp
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, van Dorp et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Conformational dynamics of auto-inhibition in the ER calcium sensor STIM1
eLife 10:e66194.
https://doi.org/10.7554/eLife.66194
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