Effects of Ser16 Phosphorylation on the Allosteric Transitions of Phospholamban/Ca2+-ATPase Complex

Nathaniel Traaseth, D. D. Thomas, G. Veglia

Research output: Contribution to journalArticle

Abstract

Phosphorylation by protein kinase A and dephosphorylation by protein phosphatase 1 modulate the inhibitory activity of phospholamban (PLN), the endogenous regulator of the sarco(endo)plasmic reticulum calcium Ca2+ ATPase (SERCA). This cyclic mechanism constitutes the driving force for calcium reuptake from the cytoplasm into the myocite lumen, regulating cardiac contractility. PLN undergoes a conformational transition between a relaxed (R) and tense (T) state, an equilibrium perturbed by the addition of SERCA. Here, we show that the single phosphoryl transfer at Ser16 induces a more pronounced conformational switch to the R state in phosphorylated PLN (pPLN). The binding affinity of PLN to SERCA is not affected (Kd values for the transmembrane domains of pPLN and PLN are ∼60 μM), supporting the hypothesis that phosphorylation at Ser16 does not dissociate PLN from SERCA. However, the binding surface and dynamics in domain Ib (residues 22-31) change substantially upon phosphorylation. Since PLN can be singly or doubly phosphorylated at Ser16 and Thr17, we propose that these sites remotely control the conformation of domain Ib. These findings constitute a paradigm for how post-translational modifications such as phosphorylation in the cytoplasmic portion of membrane proteins control intramembrane protein-protein interactions.

Original languageEnglish (US)
Pages (from-to)1041-1050
Number of pages10
JournalJournal of Molecular Biology
Volume358
Issue number4
DOIs
StatePublished - May 12 2006

Fingerprint

Calcium-Transporting ATPases
Phosphorylation
Protein Phosphatase 1
Reticulum
Post Translational Protein Processing
Cyclic AMP-Dependent Protein Kinases
phospholamban
Membrane Proteins
Cytoplasm
Proteins
Cell Membrane
Calcium

Keywords

  • detergent micelles
  • NMR
  • phospholamban
  • phosphorylated phospholamban
  • SERCA

ASJC Scopus subject areas

  • Virology

Cite this

Effects of Ser16 Phosphorylation on the Allosteric Transitions of Phospholamban/Ca2+-ATPase Complex. / Traaseth, Nathaniel; Thomas, D. D.; Veglia, G.

In: Journal of Molecular Biology, Vol. 358, No. 4, 12.05.2006, p. 1041-1050.

Research output: Contribution to journalArticle

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