Determination of the Dynamics, Structure, and Orientation of the Transmembrane Segment of ErbB2 in Model Membranes Using Solid-State NMR Spectroscopy

Abstract

Abstract : The objective of the proposed research was to investigate the structural properties of the transmembrane helix of the ErbB2 receptor utilizing solid-state nuclear magnetic resonance (NMR) spectroscopy and Molecular dynamics (MD) simulations. 15N Solid-state NMR results demonstrated that TM-ErbB2 has a transmembrane helical domain and that the orientation of the transmembrane domain is 24 5 in shorter chain dimyristoylphosphocholine and 11 3 in palmitoyloleoyphosphocholine. The orientation is dictated by the hydrophobic thickness of the synthetic phospholipid bilayers. Molecular dynamics simulations analysis demonstrated that in shorter chain lipids TM-ErbB2 also makes a tilt angle of about 28 5 with respect to the bilayer normal whereas in longer chain lipids, the tilt angle was found to be 14 4. We also conducted dimeirzation studies with the wild type TM-ErbB2 within the membrane bilayer environments. One of the motifs responsible for dimerization (SAVVG) was mutated to alanines whereas the other motif (GVVFG) was left intact. The GVVFG motif still had the ability to dimerize indicating that homodimerization is dictated by at least one of these motifs in full length receptor.