N-terminus oligomerization regulates the function of cardiac ryanodine receptors.
The ryanodine receptor (RyR) is an ion channel composed of four identical subunits mediating calcium efflux from the endo/sarcoplasmic reticulum of excitable and non-excitable cells. We present several lines of evidence indicating that the RyR2 N-terminus is capable of self-association. A combination of yeast two-hybrid screens, co-immunoprecipitation analysis, chemical crosslinking and gel filtration assays collectively demonstrate that a RyR2 N-terminal fragment possesses the intrinsic ability to oligomerize, enabling apparent tetramer formation. Interestingly, N-terminus tetramerization mediated by endogenous disulfide bond formation occurs in native RyR2, but notably not in RyR1. Disruption of N-terminal inter-subunit interactions within RyR2 results in dysregulation of channel activation at diastolic Ca(2+) concentrations from ryanodine binding and single channel measurements. Our findings suggest that the N-terminus interactions mediating tetramer assembly are involved in RyR channel closure, identifying a crucial role for this structural association in the dynamic regulation of intracellular Ca(2+) release.
Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff CF14 4XN, UK.
Spyros
S
Zissimopoulos
Cedric
C
Viero
Monika
M
Seidel
Bevan
B
Cumbes
Judith
J
White
Iris
I
Cheung
Richard
R
Stewart
Loice H
LH
Jeyakumar
Sidney
S
Fleischer
Saptarshi
S
Mukherjee
N Lowri
NL
Thomas
Alan J
AJ
Williams
F Anthony
FA
Lai
D020816:Amino Acid Motifs; D000818:Animals; D002118:Calcium / Q000378:metabolism; D006801:Humans; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000378:metabolism*; D055503:Protein Multimerization; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013552:Swine
D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium
Calcium release channel; Cardiac ryanodine receptor; N-terminus; Oligomerization