Ca2+-inactivation of the mammalian ryanodine receptor type 1 in a lipidic environment revealed by cryo-EM
- Virginia Commonwealth University, United States
Abstract
Activation of the intracellular Ca2+ channel ryanodine receptor (RyR) triggers a cytosolic Ca2+ surge, while elevated cytosolic Ca2+ inhibits the channel in a negative feedback mechanism. Cryo-EM of rabbit RyR1 embedded in nanodiscs under partially inactivating Ca2+ conditions revealed an open and a closed-inactivated conformation. Ca2+ binding to the high affinity site engages the central and C-terminal domains into a block, which pries the S6 four-helix bundle open. Further rotation of this block pushes S6 toward the central axis, closing (inactivating) the channel. Main characteristics of the Ca2+-inactivated conformation are downward conformation of the cytoplasmic assembly and tightly-knit subunit interface contributed by a fully occupied Ca2+ activation site, two inter-subunit resolved lipids, and two salt bridges between the EF hand domain and the S2-S3 loop validated by disease-causing mutations. The structural insight illustrates the prior Ca2+ activation prerequisite for Ca2+ inactivation and provides for seamless transition from inactivated to closed conformations.
Data availability
The cryo-EM maps and models are available in the EMDB and PDB databases.
Article and author information
Author details
Funding
National Institutes of Health (R01 AR068431)
- Montserrat Samsó
Muscular Dystrophy Association (MDA 352845)
- Montserrat Samsó
National Institutes of Health (U24 GM116790)
- Montserrat Samsó
National Institutes of Health (HSSN261200800001E)
- Montserrat Samsó
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocol #AD10001029 of Virginia Commonwealth. Animals were deeply anesthetized for tissue harvesting, and every effort was made to minimize suffering.
Copyright
© 2022, Nayak & Samsó
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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Ca2+-inactivation of the mammalian ryanodine receptor type 1 in a lipidic environment revealed by cryo-EM
eLife 11:e75568.
https://doi.org/10.7554/eLife.75568
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