Discovery of novel gating checkpoints in the Orai1 calcium channel by systematic analysis of constitutively active mutants of its paralogs and orthologs.

Autor:	Augustynek B; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Gyimesi G; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Dernič J; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Sallinger M; Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria., Albano G; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Klesse GJ; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Kandasamy P; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Grabmayr H; Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria., Frischauf I; Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, A-4020 Linz, Austria., Fuster DG; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland., Peinelt C; Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland., Hediger MA; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland. Electronic address: matthias.hediger@ibmm.unibe.ch., Bhardwaj R; Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department of Biomedical Research, Inselspital, University of Bern, Freiburgstrasse 15, CH-3010 Bern, Switzerland; Current address: Signal Transduction Laboratory, National Institute of Environmental Health Sciences, NIH, 111 TW Alexander Drive, NC 27709, USA. Electronic address: rajesh.bhardwaj@nih.gov.
Jazyk:	angličtina
Zdroj:	Cell calcium [Cell Calcium] 2022 Jul; Vol. 105, pp. 102616. Date of Electronic Publication: 2022 Jun 22.
DOI:	10.1016/j.ceca.2022.102616
Abstrakt:	In humans, there are three paralogs of the Orai Ca 2+ channel that form the core of the store-operated calcium entry (SOCE) machinery. While the STIM-mediated gating mechanism of Orai channels is still under active investigation, several artificial and natural variants are known to cause constitutive activity of the human Orai1 channel. Surprisingly, little is known about the conservation of the gating checkpoints among the different human Orai paralogs and orthologs in other species. In our work, we show that the mutation corresponding to the activating mutation H134A in transmembrane helix 2 (TM2) of human Orai1 also activates Orai2 and Orai3, likely via a similar mechanism. However, this cross-paralog conservation does not apply to the "ANSGA" nexus mutations in TM4 of human Orai1, which is reported to mimic the STIM1-activated state of the channel. In investigating the mechanistic background of these differences, we identified two positions, H171 and F246 in human Orai1, that are not conserved among paralogs and that seem to be crucial for the channel activation triggered by the "ANSGA" mutations in Orai1. However, mutations of the same residues still allow gating of Orai1 by STIM1, suggesting that the ANSGA mutant of Orai1 may not be a surrogate for the STIM1-activated state of the Orai1 channel. Our results shed new light on these important gating checkpoints and show that the gating mechanism of Orai channels is affected by multiple factors that are not necessarily conserved among orai homologs, such as the TM4-TM3 coupling. (Copyright © 2022. Published by Elsevier Ltd.)
Databáze:	MEDLINE
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