Secondary structure and orientation of a chemically synthesized mitochondrial signal sequence in phospholipid bilayers.
A pre-sequence of 25 amino acids is required for import of yeast cytochrome oxidase subunit IV into mitochondria. Structure and orientation of the 25 amino acids synthesized peptide (p25) in a lipid bilayer were investigated by infrared attenuated total reflection spectroscopy. This method allowed to overcome the difficulties related to the optical turbidity due to the light scattering on membrane fragments which prevents the use of circular dichroism. We demonstrate here that incubation of the peptide with DOPC (dioleoylphosphatidylcholine) and DOPC-CL (dioleoylphosphatidylcholine - cardiolipin) liposomes is accompanied by an increase in alpha-helical content as compared to beta structure. Polarisation measurements indicate that the amphipathic helical segment is inserted parallel to the lipid acyl chains in cardiolipin containing liposomes.
Goormaghtigh
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E
Laboratoire de Chimie-Physique des Macromolécules, Université Libre de Bruxelles, Belgium.
Martin
I
I
Vandenbranden
M
M
Brasseur
R
R
Ruysschaert
J M
JM
D002308:Cardiolipins; D003576:Electron Transport Complex IV / Q000502:physiology*; D066298:In Vitro Techniques; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D011487:Protein Conformation; D021382:Protein Sorting Signals / Q000138:chemical synthesis; D013055:Spectrophotometry, Infrared
D002308:Cardiolipins; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D021382:Protein Sorting Signals; D003576:Electron Transport Complex IV