Voltage gating at the selectivity filter of the Ca2+ release-activated Ca2+ channel induced by mutation of the Orai1 protein

The Ca(2+) release-activated Ca(2+) (CRAC) channel is a plasma membrane (PM) channel that is uniquely activated when free Ca(2+) level in the endoplasmic reticulum (ER) is substantially reduced. Several small interfering RNA screens identified two membrane proteins, Orai1 and STIM1, to be essential for the CRAC channel function. STIM1 appears to function in the PM and as the Ca(2+) sensor in the ER. Orai1 is forming the pore of the CRAC channel. Despite the recent breakthroughs, a mechanistic understanding of the CRAC channel gating is still lacking. Here we reveal new insights on the structure-function relationship of STIM1 and Orai1. Our data suggest that the cytoplasmic coiled-coil region of STIM1 provides structural means for coupling of the ER membrane to the PM to activate the CRAC channel. We mutated two hydrophobic residues in this region to proline (L286P/L292P) to introduce a kink in the first alpha-helix of the coiled-coil domain. This STIM1 mutant caused a dramatic inhibition of the CRAC channel gating compared with the wild type. Structure-function analysis of the Orai1 protein revealed the presence of intrinsic voltage gating of the CRAC channel. A mutation of Orai1 (V102I) close to the selectivity filter modified CRAC channel voltage sensitivity. Expression of the Orai1(V102I) mutant resulted in slow voltage gating of the CRAC channel by negative potentials. The results revealed that the alteration of Val(102) develops voltage gating in the CRAC channel. Our data strongly suggest the presence of a novel voltage gating mechanism at the selectivity filter of the CRAC channel.

Medienart:

Artikel

Erscheinungsjahr:

2008

Erschienen:

2008

Enthalten in:

Zur Gesamtaufnahme - volume:283

Enthalten in:

The Journal of biological chemistry - 283(2008), 22 vom: 30. Mai, Seite 14938-45

Sprache:

Englisch

Beteiligte Personen:

Spassova, Maria A [VerfasserIn]
Hewavitharana, Thamara [VerfasserIn]
Fandino, Richard A [VerfasserIn]
Kaya, Asli [VerfasserIn]
Tanaka, Jacqueline [VerfasserIn]
Gill, Donald L [VerfasserIn]

Themen:

Calcium
Calcium Channels
Journal Article
Membrane Proteins
Neoplasm Proteins
ORAI1 Protein
ORAI1 protein, human
Research Support, N.I.H., Extramural
STIM1 protein, human
SY7Q814VUP
Stromal Interaction Molecule 1

Anmerkungen:

Date Completed 17.07.2008

Date Revised 20.10.2021

published: Print-Electronic

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM175908257