STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening
Najjar H, Weiß S, Horvath F, Hopl V, Tiffner A, Höbarth L, Söllner J, Fröhlich M, Prantl M, Müller N, Nazarenko Y, Harant S, Weissenböck L, Grabmayr H, Sallinger M, Maltan L, Echefu LV, Radiskovic T, Leopold M, Lindinger S, Humer C, Höglinger C, Krobath H, Renger T, Derler I. 2025. STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening. Cell Reports Physical Science. 6(6), 102623.
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Author
Najjar, Hadil;
Weiß, Sarah;
Horvath, FerdinandISTA;
Hopl, Valentina;
Tiffner, Adéla;
Höbarth, Lorenz;
Söllner, Julia;
Fröhlich, Maximilian;
Prantl, Magdalena;
Müller, Nora;
Nazarenko, Yuliia;
Harant, Selina
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All
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Abstract
The Ca2+-release-activated Ca2+ (CRAC) channel Orai1 is activated by interaction with the Ca2+ sensor Stromal Interaction Molecule 1 (STIM1). Owing to the lack of structurally resolved Orai1/STIM1 complexes, the impact of their coupling on individual Orai1 transmembrane domain (TM) movements is unclear. This study investigates STIM1-independent and STIM1-dependent Orai1-TM dynamics using photocrosslinking unnatural amino acids (UAAs) at each individual TM position. We primarily identify CRAC-channel-like currents directly after UAA incorporation or additional UV-light irradiation at TM3 sites that interface with non-pore-lining TMs. Using UAAs combined with conventional site-directed mutagenesis and molecular dynamics simulations, we discover that pore opening involves a widening of interfaces formed by TM3 with non-pore-lining TMs. Orai1 mutants with a UAA in TM3 exhibit weaker STIM1-induced activation after UV exposure, possibly caused by a restricted widening of non-pore-lining TM interfaces. We demonstrate that photocrosslinking UAAs are excellent tools for improving our understanding of key determinants and ion channel dynamics modulating pore opening.
Publishing Year
Date Published
2025-06-18
Journal Title
Cell Reports Physical Science
Publisher
Elsevier
Acknowledgement
We thank S. Buchegger for excellent technical assistance. This research was funded by the Austrian Science Fund (FWF) projects https://doi.org/10.55776/P32851, https://doi.org/10.55776/P35900, and https://doi.org/10.55776/P36202 to I.D. and https://doi.org/10.55776/PAT6871323 to A.T. N.M. is funded within the DOC program of the OeAW (Austrian Academy of Science). For open access purposes, the author has applied a CC BY public copyright license to any author-accepted manuscript version arising from this submission.
Volume
6
Issue
6
Article Number
102623
eISSN
IST-REx-ID
Cite this
Najjar H, Weiß S, Horvath F, et al. STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening. Cell Reports Physical Science. 2025;6(6). doi:10.1016/j.xcrp.2025.102623
Najjar, H., Weiß, S., Horvath, F., Hopl, V., Tiffner, A., Höbarth, L., … Derler, I. (2025). STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening. Cell Reports Physical Science. Elsevier. https://doi.org/10.1016/j.xcrp.2025.102623
Najjar, Hadil, Sarah Weiß, Ferdinand Horvath, Valentina Hopl, Adéla Tiffner, Lorenz Höbarth, Julia Söllner, et al. “STIM1-Induced Widening of Non-Pore-Lining TM Interfaces Is Crucial for Orai1 Pore Opening.” Cell Reports Physical Science. Elsevier, 2025. https://doi.org/10.1016/j.xcrp.2025.102623.
H. Najjar et al., “STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening,” Cell Reports Physical Science, vol. 6, no. 6. Elsevier, 2025.
Najjar H, Weiß S, Horvath F, Hopl V, Tiffner A, Höbarth L, Söllner J, Fröhlich M, Prantl M, Müller N, Nazarenko Y, Harant S, Weissenböck L, Grabmayr H, Sallinger M, Maltan L, Echefu LV, Radiskovic T, Leopold M, Lindinger S, Humer C, Höglinger C, Krobath H, Renger T, Derler I. 2025. STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening. Cell Reports Physical Science. 6(6), 102623.
Najjar, Hadil, et al. “STIM1-Induced Widening of Non-Pore-Lining TM Interfaces Is Crucial for Orai1 Pore Opening.” Cell Reports Physical Science, vol. 6, no. 6, 102623, Elsevier, 2025, doi:10.1016/j.xcrp.2025.102623.
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