title: Probing the interaction of Arg9Cys mutated phospholamban with phospholipid bilayers by solid-state NMR spectroscopy.
abstract: Phospholamban (PLB) is a 52 amino acid integral membrane protein that interacts with the sarcoplasmic reticulum Ca(2+) ATPase (SERCA) and helps to regulate Ca(2+) flow. PLB inhibits SERCA impairing Ca(2+) translocation. The inhibition can be relieved upon phosphorylation of PLB. The Arg9 to Cys (R9C) mutation is a loss of function mutation with reduced inhibitory potency. The effect R9C PLB has on the membrane surface and the hydrophobic region dynamics was investigated by (31)P and (2)H solid-state NMR spectroscopy in multilamellar vesicles (MLVs). The (31)P NMR spectra indicate that, like the phosphorylated PLB (P-PLB), the mutated R9C-PLB protein has significantly less interaction with the lipid bilayer headgroup when compared to wild-type PLB (WT-PLB). Similar to P-PLB, R9C-PLB slightly decreases (31)P T1 values in the lipid headgroup region. (2)H SCD order parameters of (2)H nuclei along the lipid acyl chain decrease less dramatically for R9C-PLB and P-PLB when compared to WT-PLB. The results suggest that R9C-PLB interacts less with the membrane surface and hydrophobic region than WT-PLB. Detachment of the cytoplasmic domain of R9C-PLB from the membrane surface could be related to its loss of function.
authors.affiliation: Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
authors.forename: Xueting
authors.initials: X
authors.lastname: Yu
authors.forename: Gary A
authors.initials: GA
authors.lastname: Lorigan
mesh_terms: D001120:Arginine / Q000235:genetics*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D003545:Cysteine / Q000235:genetics*; D008051:Lipid Bilayers; D015335:Molecular Probes; D019906:Nuclear Magnetic Resonance, Biomolecular; D010743:Phospholipids / Q000737:chemistry*; D000099211:Phospholamban
chemical_list: D001120:Arginine; D002135:Calcium-Binding Proteins; D003545:Cysteine; D008051:Lipid Bilayers; D015335:Molecular Probes; D010743:Phospholipids; D000099211:Phospholamban
keywords: Membrane interaction; Multilamellar vesicle; Phospholamban; Solid-state NMR spectroscopy