0000000000418911
AUTHOR
Stephan L. Grage
The Alignment of Membrane-Active Peptides Depends on the Lipid Phase State as Viewed by solid state 19F-NMR
Amphipathic membrane-active peptides (antimicrobial, hemolytic, cell-penetrating, fusogenic, etc.) achieve their functions by distinct interaction with lipid bilayers. Some typical structural modes are described in terms of models like the “barrel stave”, “toroidal pore”, “carpet” etc. These models are related to the alignment states of the peptides in the lipid bilayers (surface bound “S-state”, inserted “I-state” or tilted “T-state”), which can be readily characterized by solid state NMR. When determining such alignment, factors like peptide/lipid ratio, charge of the bilayer surface, thickness of the bilayer core, presence of cholesterol, and humidity are typically investigated. Yet, the…
Canonical azimuthal rotations and flanking residues constrain the orientation of transmembrane helices.
AbstractIn biological membranes the alignment of embedded proteins provides crucial structural information. The transmembrane (TM) parts have well-defined secondary structures, in most cases α-helices and their orientation is given by a tilt angle and an azimuthal rotation angle around the main axis. The tilt angle is readily visualized and has been found to be functionally relevant. However, there exist no general concepts on the corresponding azimuthal rotation. Here, we show that TM helices prefer discrete rotation angles. They arise from a combination of intrinsic properties of the helix geometry plus the influence of the position and type of flanking residues at both ends of the hydrop…