Quantification of the effects of a ryanodine receptor channel mutation on interaction with a ryanoid.
Understanding the nature of the interaction of the plant alkaloid ryanodine with its receptor channel (RyR) is important to aid interpretation of physiological studies and provide structure-function information about RyR. We present here the first quantitative description of the relative single-channel kinetic effects of a single-point mutation in RyR2. We exploit the well-characterized ryanoid 8beta-amino-9alpha-hydroxyryanodine that displays reversible kinetics with RyR2. We explicitly show that the effect of the Q4863A mutation is to increase the apparent dissociation constant by increasing the apparent dissociation rate of the ryanoid. The voltage-dependence of the interaction displays no change. We infer that Q4863 is not involved with the voltage-drop but is able to influence ryanoid-bound structural changes. We discuss structural mechanisms by which this mutation could affect ryanoid interaction.
Ranatunga
Kishani M
KM
Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, UK.
Chen
S R Wayne
SR
Ruest
Luc
L
Welch
William
W
Williams
Alan J
AJ
D000409:Alanine / Q000737:chemistry; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D005973:Glutamine / Q000737:chemistry; D015640:Ion Channel Gating; D007700:Kinetics; D008024:Ligands; D051379:Mice; D008956:Models, Chemical; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D021281:Quantitative Structure-Activity Relationship; D012433:Ryanodine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
C502871:8beta-amino-9alpha-hydroxyryanodine; D008024:Ligands; D050505:Mutant Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D005973:Glutamine; D012433:Ryanodine; D000409:Alanine; D002118:Calcium