Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation
The calcium release-activated calcium channel Orai regulates Ca2+ entry into non-excitable cells and is required for proper immune function. While the channel typically opens following Ca2+ release from the endoplasmic reticulum, certain pathologic mutations render the channel constitutively open. P...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2020-11-01
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| Series: | eLife |
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| Online Access: | https://elifesciences.org/articles/62772 |
| _version_ | 1818019338915938304 |
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| author | Xiaowei Hou Ian R Outhwaite Leanne Pedi Stephen Barstow Long |
| author_facet | Xiaowei Hou Ian R Outhwaite Leanne Pedi Stephen Barstow Long |
| author_sort | Xiaowei Hou |
| collection | DOAJ |
| description | The calcium release-activated calcium channel Orai regulates Ca2+ entry into non-excitable cells and is required for proper immune function. While the channel typically opens following Ca2+ release from the endoplasmic reticulum, certain pathologic mutations render the channel constitutively open. Previously, using one such mutation (H206A), we obtained low (6.7 Å) resolution X-ray structural information on Drosophila melanogaster Orai in an open conformation (Hou et al., 2018). Here we present a structure of this open conformation at 3.3 Å resolution using fiducial-assisted cryo-electron microscopy. The improved structure reveals the conformations of amino acids in the open pore, which dilates by outward movements of subunits. A ring of phenylalanine residues repositions to expose previously shielded glycine residues to the pore without significant rotational movement of the associated helices. Together with other hydrophobic amino acids, the phenylalanines act as the channel’s gate. Structured M1–M2 turrets, not evident previously, form the channel’s extracellular entrance. |
| first_indexed | 2024-04-14T07:50:58Z |
| format | Article |
| id | doaj.art-95d2107fa1774fe6bb3ba54fe465fdff |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-14T07:50:58Z |
| publishDate | 2020-11-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-95d2107fa1774fe6bb3ba54fe465fdff2022-12-22T02:05:12ZengeLife Sciences Publications LtdeLife2050-084X2020-11-01910.7554/eLife.62772Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformationXiaowei Hou0Ian R Outhwaite1https://orcid.org/0000-0003-2037-3261Leanne Pedi2Stephen Barstow Long3https://orcid.org/0000-0002-8144-1398Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United StatesStructural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United StatesStructural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United StatesStructural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United StatesThe calcium release-activated calcium channel Orai regulates Ca2+ entry into non-excitable cells and is required for proper immune function. While the channel typically opens following Ca2+ release from the endoplasmic reticulum, certain pathologic mutations render the channel constitutively open. Previously, using one such mutation (H206A), we obtained low (6.7 Å) resolution X-ray structural information on Drosophila melanogaster Orai in an open conformation (Hou et al., 2018). Here we present a structure of this open conformation at 3.3 Å resolution using fiducial-assisted cryo-electron microscopy. The improved structure reveals the conformations of amino acids in the open pore, which dilates by outward movements of subunits. A ring of phenylalanine residues repositions to expose previously shielded glycine residues to the pore without significant rotational movement of the associated helices. Together with other hydrophobic amino acids, the phenylalanines act as the channel’s gate. Structured M1–M2 turrets, not evident previously, form the channel’s extracellular entrance.https://elifesciences.org/articles/62772ion channelcalcium channelgatingmembrane protein |
| spellingShingle | Xiaowei Hou Ian R Outhwaite Leanne Pedi Stephen Barstow Long Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation eLife ion channel calcium channel gating membrane protein |
| title | Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation |
| title_full | Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation |
| title_fullStr | Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation |
| title_full_unstemmed | Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation |
| title_short | Cryo-EM structure of the calcium release-activated calcium channel Orai in an open conformation |
| title_sort | cryo em structure of the calcium release activated calcium channel orai in an open conformation |
| topic | ion channel calcium channel gating membrane protein |
| url | https://elifesciences.org/articles/62772 |
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