TY - JOUR
T1 - Allosteric regulation of SERCA by phosphorylationmediated conformational shift of phospholamban
AU - Gustavsson, Martin
AU - Verardi, Raffaello
AU - Mullen, Daniel G.
AU - Mote, Kaustubh R.
AU - Traaseth, Nathaniel J.
AU - Gopinath, T.
AU - Veglia, Gianluigi
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2013/10/22
Y1 - 2013/10/22
N2 - The membrane protein complex between the sarcoplasmic reticulum Ca 2+-ATPase (SERCA) and phospholamban (PLN) controls Ca2+ transport in cardiomyocytes, thereby modulating cardiac contractility. β-Adrenergic-stimulated phosphorylation of PLN at Ser- 16 enhances SERCA activity via an unknown mechanism. Using solid-state nuclear magnetic resonance spectroscopy, we mapped the physical interactions between SERCA and both unphosphorylated and phosphorylated PLN in membrane bilayers. We found that the allosteric regulation of SERCA depends on the conformational equilibrium of PLN, whose cytoplasmic regulatory domain interconverts between three different states: a ground T state (helical and membrane associated), an excited R state (unfolded and membrane detached), and a B state (extended and enzymebound), which is noninhibitory. Phosphorylation at Ser-16 of PLN shifts the populations toward the B state, increasing SERCA activity. We conclude that PLN's conformational equilibrium is central to maintain SERCA's apparent Ca 2+ affinity within a physiological window. This model represents a paradigm shift in our understanding of SERCA regulation by posttranslational phosphorylation and suggests strategies for designing innovative therapeutic approaches to enhance cardiac muscle contractility.
AB - The membrane protein complex between the sarcoplasmic reticulum Ca 2+-ATPase (SERCA) and phospholamban (PLN) controls Ca2+ transport in cardiomyocytes, thereby modulating cardiac contractility. β-Adrenergic-stimulated phosphorylation of PLN at Ser- 16 enhances SERCA activity via an unknown mechanism. Using solid-state nuclear magnetic resonance spectroscopy, we mapped the physical interactions between SERCA and both unphosphorylated and phosphorylated PLN in membrane bilayers. We found that the allosteric regulation of SERCA depends on the conformational equilibrium of PLN, whose cytoplasmic regulatory domain interconverts between three different states: a ground T state (helical and membrane associated), an excited R state (unfolded and membrane detached), and a B state (extended and enzymebound), which is noninhibitory. Phosphorylation at Ser-16 of PLN shifts the populations toward the B state, increasing SERCA activity. We conclude that PLN's conformational equilibrium is central to maintain SERCA's apparent Ca 2+ affinity within a physiological window. This model represents a paradigm shift in our understanding of SERCA regulation by posttranslational phosphorylation and suggests strategies for designing innovative therapeutic approaches to enhance cardiac muscle contractility.
KW - Magic angle spinning
KW - Paramagnetic relaxation enhancement
KW - Protein-protein interactions
KW - Solid-state NMR
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U2 - 10.1073/pnas.1303006110
DO - 10.1073/pnas.1303006110
M3 - Article
C2 - 24101520
AN - SCOPUS:84886402422
SN - 0027-8424
VL - 110
SP - 17338
EP - 17343
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 43
ER -