Molecular mechanism of the severe MH/CCD mutation Y522S in skeletal ryanodine receptor (RyR1) by cryo-EM.
Proc Natl Acad Sci U S A
; 119(30): e2122140119, 2022 07 26.
Article
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| ID: mdl-35867837
ABSTRACT
Ryanodine receptors (RyRs) are main regulators of intracellular Ca2+ release and muscle contraction. The Y522S mutation of RyR1 causes central core disease, a weakening myopathy, and malignant hyperthermia, a sudden and potentially fatal response to anesthetics or heat. Y522 is in the core of the N-terminal subdomain C of RyR1 and the mechanism of how this mutation orchestrates malfunction is unpredictable for this 2-MDa ion channel, which has four identical subunits composed of 15 distinct cytoplasmic domains each. We expressed and purified the RyR1 rabbit homolog, Y523S, from HEK293 cells and reconstituted it in nanodiscs under closed and open states. The high-resolution cryogenic electron microscopic (cryo-EM) three-dimensional (3D) structures show that the phenyl ring of Tyr functions in a manner analogous to a "spacer" within an α-helical bundle. Mutation to the much smaller Ser alters the hydrophobic network within the bundle, triggering rearrangement of its α-helices with repercussions in the orientation of most cytoplasmic domains. Examining the mutation-induced readjustments exposed a series of connected α-helices acting as an â¼100 Å-long lever One end protrudes toward the dihydropyridine receptor, its molecular activator (akin to an antenna), while the other end reaches the Ca2+ activation site. The Y523S mutation elicits channel preactivation in the absence of any activator and full opening at 1.5 µM free Ca2+, increasing by â¼20-fold the potency of Ca2+ to activate the channel compared with RyR1 wild type (WT). This study identified a preactivated pathological state of RyR1 and a long-range lever that may work as a molecular switch to open the channel.
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Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Músculo Esquelético
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Canal Liberador de Calcio Receptor de Rianodina
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Miopatía del Núcleo Central
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Hipertermia Maligna
Tipo de estudio:
Prognostic_studies
Límite:
Animals
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Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2022
Tipo del documento:
Article