Spectroscopic validation of the pentameric structure of phospholamban

Nathaniel J. Traaseth, Raffaello Verardi, Kurt D. Torgersen, Christine B. Karim, David D. Thomas, Gianluigi Veglia

Research output: Contribution to journalArticle

Abstract

Phospholamban (PLN) regulates calcium translocation within cardiac myocytes by shifting sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) affinity for calcium. Although the monomeric form of PLN (6 kDa) is the principal inhibitory species, recent evidence suggests that the PLN pentamer (30 kDa) also is able to bind SERCA. To date, several membrane architectures of the pentamer have been proposed, with different topological orientations for the cytoplasmic domain: (i) extended from the bilayer normal by 50-60°; (ii) continuous α-helix tilted 28° relative to the bilayer normal; (iii) pinwheel geometry, with the cytoplasmic helix perpendicular to the bilayer normal and in contact with the surface of the bilayer; and (iv) bellflower structure, in which the cytoplasmic domain helix makes ≈20° angle with respect to the membrane bilayer normal. Using a variety of cell membrane mimicking systems (i.e., lipid vesicles, oriented lipid bilayers, and detergent micelles) and a combination of multidimensional solution/solid-state NMR and EPR spectroscopies, we tested the different structural models. We conclude that the pinwheel topology is the predominant conformation of pentameric PLN, with the cytoplasmic domain interacting with the membrane surface. We propose that the interaction with the bilayer precedes SERCA binding and may mediate the interactions with other proteins such as protein kinase A and protein phosphatase 1.

Original languageEnglish (US)
Pages (from-to)14676-14681
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number37
DOIs
StatePublished - Sep 11 2007

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Keywords

  • Ca-ATPase
  • EPR
  • Membrane protein
  • Protein dynamics
  • Solid-state NMR

ASJC Scopus subject areas

  • General

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