[HTML][HTML] Structural insights into the human RyR2 N-terminal region involved in cardiac arrhythmias

Ľ Borko, V Bauerová-Hlinková, E Hostinová… - … Section D: Biological …, 2014 - scripts.iucr.org
Ľ Borko, V Bauerová-Hlinková, E Hostinová, J Gašperík, K Beck, FA Lai, A Zahradníková
Acta Crystallographica Section D: Biological Crystallography, 2014scripts.iucr.org
Human ryanodine receptor 2 (hRyR2) mediates calcium release from the sarcoplasmic
reticulum, enabling cardiomyocyte contraction. The N-terminal region of hRyR2 (amino
acids 1–606) is the target of> 30 arrhythmogenic mutations and contains a binding site for
phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under
near-physiological conditions, as well as a homology model of the hRyR2 N-terminal region,
are presented. The N-terminus is held together by a unique network of interactions among …
Human ryanodine receptor 2 (hRyR2) mediates calcium release from the sarcoplasmic reticulum, enabling cardiomyocyte contraction. The N-terminal region of hRyR2 (amino acids 1–606) is the target of >30 arrhythmogenic mutations and contains a binding site for phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under near-physiological conditions, as well as a homology model of the hRyR2 N-terminal region, are presented. The N-terminus is held together by a unique network of interactions among its three domains, A, B and C, in which the central helix (amino acids 410–437) plays a prominent stabilizing role. Importantly, the anion-binding site reported for the mouse RyR2 N-terminal region is notably absent from the human RyR2. The structure concurs with the differential stability of arrhythmogenic mutations in the central helix (R420W, I419F and I419F/R420W) which are owing to disparities in the propensity of mutated residues to form energetically favourable or unfavourable contacts. In solution, the N-terminus adopts a globular shape with a prominent tail that is likely to involve residues 545–606, which are unresolved in the crystal structure. Docking the N-terminal domains into cryo-electron microscopy maps of the closed and open RyR1 conformations reveals Cα atom movements of up to 8 Å upon channel gating, and predicts the location of the leucine–isoleucine zipper segment and the interaction site for spinophilin and phosphoprotein phosphatase 1 on the RyR surface.
International Union of Crystallography