@article{19846,
  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.},
  author       = {Najjar, Hadil and Weiß, Sarah and Horvath, Ferdinand and Hopl, Valentina and Tiffner, Adéla and Höbarth, Lorenz and Söllner, Julia and Fröhlich, Maximilian and Prantl, Magdalena and Müller, Nora and Nazarenko, Yuliia and Harant, Selina and Weissenböck, Lukas and Grabmayr, Herwig and Sallinger, Matthias and Maltan, Lena and Echefu, Linda V. and Radiskovic, Tamara and Leopold, Melanie and Lindinger, Sonja and Humer, Christina and Höglinger, Carmen and Krobath, Heinrich and Renger, Thomas and Derler, Isabella},
  issn         = {2666-3864},
  journal      = {Cell Reports Physical Science},
  number       = {6},
  publisher    = {Elsevier},
  title        = {{STIM1-induced widening of non-pore-lining TM interfaces is crucial for Orai1 pore opening}},
  doi          = {10.1016/j.xcrp.2025.102623},
  volume       = {6},
  year         = {2025},
}