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Differential roles of the C and N termini of Orai1 protein in interacting with stromal interaction molecule 1 (STIM1) for Ca2+ release-activated Ca2+ (CRAC) channel activation.
J Biol Chem. 2013 Apr 19; 288(16):11263-72.JB

Abstract

The entry of extracellular Ca(2+), which is mediated by Ca(2+) release-activated Ca(2+) (CRAC) channels, is essential for T cell activation and the normal functioning of other immune cells. Although the molecular components of CRAC channels, the Orai1 pore-forming subunit and the STIM1-activating subunit have been recently identified, the gating mechanism by which Orai1 channels conduct Ca(2+) entry upon Orai1-STIM1 interaction following Ca(2+) store release remains elusive. Herein, we show that C-terminal truncations or point mutations prevented Orai1 from binding to STIM1 and subsequent channel opening. In contrast, an Orai1 mutant with an N-terminal truncation interacted with but failed to be activated by STIM1. Moreover, Orai1 channels with C-terminal disruption, but not N-terminal truncation, could be gated by fused functional domains of STIM1. Interestingly, the channel activities of Orai1 mutants carrying either an N-terminal or a C-terminal truncation were restored by a methionine mutation at the putative gating hinge, the conserved Gly-98 site in the first transmembrane segment (TM1) of Orai1. Collectively, these results support a stepwise gating mechanism of STIM1-operated Orai1 channels; the initial binding between STIM1 and the C terminus of Orai1 docks STIM1 onto the N terminus of Orai1 to initiate conformational changes of the pore-lining TM1 helix of Orai1, leading to the opening of the channel.

Authors+Show Affiliations

Department of Medical Physiology, College of Medicine, Texas A&M Health Science Center, Temple, Texas 76504, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23447534

Citation

Zheng, Hongying, et al. "Differential Roles of the C and N Termini of Orai1 Protein in Interacting With Stromal Interaction Molecule 1 (STIM1) for Ca2+ Release-activated Ca2+ (CRAC) Channel Activation." The Journal of Biological Chemistry, vol. 288, no. 16, 2013, pp. 11263-72.
Zheng H, Zhou MH, Hu C, et al. Differential roles of the C and N termini of Orai1 protein in interacting with stromal interaction molecule 1 (STIM1) for Ca2+ release-activated Ca2+ (CRAC) channel activation. J Biol Chem. 2013;288(16):11263-72.
Zheng, H., Zhou, M. H., Hu, C., Kuo, E., Peng, X., Hu, J., Kuo, L., & Zhang, S. L. (2013). Differential roles of the C and N termini of Orai1 protein in interacting with stromal interaction molecule 1 (STIM1) for Ca2+ release-activated Ca2+ (CRAC) channel activation. The Journal of Biological Chemistry, 288(16), 11263-72. https://doi.org/10.1074/jbc.M113.450254
Zheng H, et al. Differential Roles of the C and N Termini of Orai1 Protein in Interacting With Stromal Interaction Molecule 1 (STIM1) for Ca2+ Release-activated Ca2+ (CRAC) Channel Activation. J Biol Chem. 2013 Apr 19;288(16):11263-72. PubMed PMID: 23447534.
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TY - JOUR T1 - Differential roles of the C and N termini of Orai1 protein in interacting with stromal interaction molecule 1 (STIM1) for Ca2+ release-activated Ca2+ (CRAC) channel activation. AU - Zheng,Hongying, AU - Zhou,Meng-Hua, AU - Hu,Changlong, AU - Kuo,Enoch, AU - Peng,Xu, AU - Hu,Junjie, AU - Kuo,Lih, AU - Zhang,Shenyuan L, Y1 - 2013/02/27/ PY - 2013/3/1/entrez PY - 2013/3/1/pubmed PY - 2013/6/14/medline SP - 11263 EP - 72 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 288 IS - 16 N2 - The entry of extracellular Ca(2+), which is mediated by Ca(2+) release-activated Ca(2+) (CRAC) channels, is essential for T cell activation and the normal functioning of other immune cells. Although the molecular components of CRAC channels, the Orai1 pore-forming subunit and the STIM1-activating subunit have been recently identified, the gating mechanism by which Orai1 channels conduct Ca(2+) entry upon Orai1-STIM1 interaction following Ca(2+) store release remains elusive. Herein, we show that C-terminal truncations or point mutations prevented Orai1 from binding to STIM1 and subsequent channel opening. In contrast, an Orai1 mutant with an N-terminal truncation interacted with but failed to be activated by STIM1. Moreover, Orai1 channels with C-terminal disruption, but not N-terminal truncation, could be gated by fused functional domains of STIM1. Interestingly, the channel activities of Orai1 mutants carrying either an N-terminal or a C-terminal truncation were restored by a methionine mutation at the putative gating hinge, the conserved Gly-98 site in the first transmembrane segment (TM1) of Orai1. Collectively, these results support a stepwise gating mechanism of STIM1-operated Orai1 channels; the initial binding between STIM1 and the C terminus of Orai1 docks STIM1 onto the N terminus of Orai1 to initiate conformational changes of the pore-lining TM1 helix of Orai1, leading to the opening of the channel. SN - 1083-351X UR - https://www.unboundmedicine.com/medline/citation/23447534/Differential_roles_of_the_C_and_N_termini_of_Orai1_protein_in_interacting_with_stromal_interaction_molecule_1__STIM1__for_Ca2+_release_activated_Ca2+__CRAC__channel_activation_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=23447534 DB - PRIME DP - Unbound Medicine ER -