Evidence from solid-state NMR for nonhelical conformations in the transmembrane domain of the amyloid precursor protein.
Evidence from solid-state NMR for nonhelical conformations in the transmembrane domain of the amyloid precursor protein.
Biophys J. 2011 Feb 2;100(3):711-9
Authors: Lu JX, Yau WM, Tycko R
The amyloid precursor protein (APP) is subject to proteolytic processing by ?-secretase within neuronal membranes, leading to Alzheimer's disease-associated ?-amyloid peptide production by cleavage near the midpoint of the*single transmembrane (TM) segment of APP. Conformational properties of the TM segment may affect its susceptibility to ?-secretase cleavage, but these properties have not been established definitively, especially in bilayer membranes with physiologically relevant lipid compositions. In this article, we report an investigation of the APP-TM conformation, using (13)C chemical shifts obtained with two-dimensional solid-state NMR spectroscopy as site-specific conformational probes. We find that the*APP-TM conformation is not a simple ?-helix, particularly at 37°C in multilamellar vesicles with compositions that mimic the composition of neuronal cell membranes. Instead, we observe a mixture of helical and nonhelical conformations at the N-*and C-termini and in the vicinity of the ?-cleavage site. Conformational plasticity of the TM segment of APP may be an important factor in the ?-secretase cleavage mechanism.
PMID: 21281586 [PubMed - in process]
Source:
PubMed