Allosteric regulation of SERCA by phosphorylation-mediated conformational shift of phospholamban

作者：Gustavsson Martin; Verardi Raffaello; Mullen Daniel G; Mote Kaustubh R; Traaseth Nathaniel J; Gopinath T; Veglia Gianluigi^*

来源：Proceedings of the National Academy of Sciences, 2013, 110(43): 17338-17343.

DOI：10.1073/pnas.1303006110

• solid-state NMR
• magic angle spinning
• protein-protein interactions
• paramagnetic relaxation enhancement

The membrane protein complex between the sarcoplasmic reticulum Ca2+-ATPase (SERCA) and phospholamban (PLN) controls Ca2+ transport in cardiomyocytes, thereby modulating cardiac contractility. beta-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 enzyme-bound), 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 Ca2+ affinity within a physiological 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.

• 出版日期2013-10-22