Investigating Structural Changes in the Lipid Bilayer upon Insertion of the Transmembrane Domain of the Membrane-Bound Protein Phospholamban Utilizing ^sup 31^P and ^sup 2^H Solid-State NMR Spectroscopy

• Published in: Biophysical journal Vol. 86; no. 3; p. 1564
• Main Authors: Dave, Paresh C, Tiburu, Elvis K, Damodaran, Krishnan, Lorigan, Gary A
• Format: Journal Article
• Language: English
• Published: New York Biophysical Society 01.03.2004
• Subjects: Amino acids; Ions; Lipids; Membranes; Proteins; Spectrum analysis
• ISSN: 0006-3495; 1542-0086

Phospholamban (PLB) is a 52-amino acid integral membrane protein that regulates the flow of Ca^sup 2+^ ions in cardiac muscle cells. In the present study, the transmembrane domain of PLB (24-52) was incorporated into phospholipid bilayers prepared from 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC). Solid-state ^sup 31^P and ^sup 2^H NMR experiments were carried out to study the behavior of POPC bilayers in the presence of the hydrophobic peptide PLB at temperatures ranging from 30°C to 60°C. The PLB peptide concentration varied from 0 mol % to 6 mol % with respect to POPC. Solid-state ^sup 31^P NMR spectroscopy is a valuable technique to study the different phases formed by phospholipid membranes. ^sup 31^P NMR results suggest that the transmembrane protein phospholamban is incorporated successfully into the bilayer and the effects are observed in the lipid lamellar phase. Simulations of the ^sup 31^P NMR spectra were carried out to reveal the formation of different vesicle sizes upon PLB insertion. The bilayer vesicles fragmented into smaller sizes by increasing the concentration of PLB with respect to POPC. Finally, molecular order parameters (S^sub CD^) were calculated by performing ^sup 2^H solid-state NMR studies on deuterated POPC (sn-1 chain) phospholipid bilayers when the PLB peptide was inserted into the membrane. [PUBLICATION ABSTRACT]