Interactions involved in the realignment of membrane-associated helices. An investigation using oriented solid-state NMR and attenuated total reflection Fourier transform infrared spectroscopies.
A series of histidine-containing peptides (LAH4X6) was designed to investigate the membrane interactions of selected side chains. To this purpose, their pH-dependent transitions from in-plane to transmembrane orientations were investigated by attenuated total reflection Fourier transform infrared and oriented solid-state NMR spectroscopies. Peptides of the same family have previously been shown to exhibit antibiotic and DNA transfection activities. Solution NMR spectroscopy indicates that these peptides form amphipathic helical structures in membrane environments, and the technique was also used to characterize the pK values of all histidines in the presence of detergent micelles. Whereas one face of the amphipathic helix is clearly hydrophobic, the opposite side is flanked by four histidines surrounding six leucine, alanine, glycine, tryptophan, or tyrosine residues, respectively. This diversity in peptide composition causes pronounced shifts in the midpoint pH of the in-plane to transmembrane helical transition, which is completely abolished for the peptides carrying the most hydrophilic amino acid residues. These properties open up a conceptually new approach to study in a quantitative manner the hydrophobic as well as specific interactions of amino acids in membranes. Notably, the resulting scale for whole residue transitions from the bilayer interface to the hydrophobic membrane interior is obtained from extended helical sequences in lipid bilayers.
Aisenbrey
Christopher
C
Institut/Faculté de Chimie, Université Louis Pasteur/CNRS LC3-UMR7177, 4 Rue Blaise Pascal, Strasbourg 67070, France.
Kinder
Rudolf
R
Goormaghtigh
Erik
E
Ruysschaert
Jean-Marie
JM
Bechinger
Burkhard
B
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism*; D004247:DNA / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008823:Micelles; D008956:Models, Chemical; D015233:Models, Statistical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D017433:Protein Structure, Secondary; D011522:Protons; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013816:Thermodynamics; D014162:Transfection; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry
D003902:Detergents; D008051:Lipid Bilayers; D008823:Micelles; D010455:Peptides; D011522:Protons; D014443:Tyrosine; D006639:Histidine; D014364:Tryptophan; D004247:DNA; D007930:Leucine; D000409:Alanine; D005998:Glycine