Structural insights into the human RyR2 N-terminal region involved in cardiac arrhythmias.
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 C(α) 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.
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Lubomír
L
Borko
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Vladena
V
Bauerová-Hlinková
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Eva
E
Hostinová
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Juraj
J
Gašperík
Cardiff University School of Dentistry, Heath Park, Cardiff CF14 4XY, Wales.
Konrad
K
Beck
Department of Cardiology, Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff CF14 4XN, Wales.
F Anthony
FA
Lai
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Alexandra
A
Zahradníková
Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava, Slovakia.
Jozef
J
Sevčík
D000595:Amino Acid Sequence; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D002712:Chlorides / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D051379:Mice; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D002712:Chlorides; D019837:Ryanodine Receptor Calcium Release Channel
X-ray and SAXS structure; arrhythmogenic mutations; human ryanodine receptor 2; molecular modelling; phosphoprotein phosphatase I binding site