Structural fluctuations between two conformational states of a transmembrane helical peptide are related to its channel-forming properties in planar lipid membranes.
Putative transmembrane helices of membrane proteins in general and channel proteins in particular often contain proline residues which may induce a bend into an otherwise regular helical structure. Here we show by fluorescence-energy-transfer measurements and molecular-dynamics calculations that, in the case of synthetic bilayer-spanning helical polypeptides, a proline-induced bend in a helix acts as a flexible element mediating rigid body motions of the helical segments. Most important, such structural fluctuations in the transmembrane helices seem to play a functional role in the formation of ionic channels in planar lipid bilayers and biological membranes.
Vogel
H
H
Institute of Physical Chemistry, Federal Institute of Technology, Lausanne, Switzerland.
Nilsson
L
L
Rigler
R
R
Meder
S
S
Boheim
G
G
Beck
W
W
Kurth
H H
HH
Jung
G
G
D000595:Amino Acid Sequence; D007473:Ion Channels / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D007473:Ion Channels; D008563:Membrane Lipids; D008565:Membrane Proteins