title: Lethal Arg9Cys phospholamban mutation hinders Ca2+-ATPase regulation and phosphorylation by protein kinase A.
abstract: The regulatory interaction of phospholamban (PLN) with Ca(2+)-ATPase controls the uptake of calcium into the sarcoplasmic reticulum, modulating heart muscle contractility. A missense mutation in PLN cytoplasmic domain (R9C) triggers dilated cardiomyopathy in humans, leading to premature death. Using a combination of biochemical and biophysical techniques both in vitro and in live cells, we show that the R9C mutation increases the stability of the PLN pentameric assembly via disulfide bridge formation, preventing its binding to Ca(2+)-ATPase as well as phosphorylation by protein kinase A. These effects are enhanced under oxidizing conditions, suggesting that oxidative stress may exacerbate the cardiotoxic effects of the PLN(R9C) mutant. These results reveal a regulatory role of the PLN pentamer in calcium homeostasis, going beyond the previously hypothesized role of passive storage for active monomers.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Kim N
authors.initials: KN
authors.lastname: Ha
authors.forename: Larry R
authors.initials: LR
authors.lastname: Masterson
authors.forename: Zhanjia
authors.initials: Z
authors.lastname: Hou
authors.forename: Raffaello
authors.initials: R
authors.lastname: Verardi
authors.forename: Naomi
authors.initials: N
authors.lastname: Walsh
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Veglia
authors.forename: Seth L
authors.initials: SL
authors.lastname: Robia
mesh_terms: D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D002311:Cardiomyopathy, Dilated / Q000235:genetics* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D020125:Mutation, Missense / Q000235:genetics*; D009200:Myocardial Contraction / Q000235:genetics* / Q000502:physiology; D018384:Oxidative Stress / Q000235:genetics; D010766:Phosphorylation; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*; D000099211:Phospholamban
chemical_list: D002118:Calcium; D002135:Calcium-Binding Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000099211:Phospholamban