Lipid-like behaviour of signal sequence peptides at air-water interface.

AMBROGGIO E. E.; FIDELIO G. D.

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 p. 708 - 714

0005-2736

Several protein transport processes in the cell are mediated by signal sequence peptides located at the N-terminal side of the mature protein sequence. To date, it is not clear the specific interaction and the stability of these peptides at the amphipathic interface of biological membranes and the relevance of the peptide conformation when they interact with lipids. We report the surface properties and the peptide-lipid interaction of three signal sequence peptides at the air-NaCl 145mM interface by using the Langmuir monolayer approach. These synthetic peptides have a natural sequence with a non-periodic amphiphilicity, where hydrophobic and hydrophilic residues are located on opposed sides of the peptide primary sequence. We show that signal sequence peptides form insoluble monolayers of high stability against lateral compression. At close packing, peptide molecular area, surface potential and the high stability of the peptide monolayer are indicative that signal sequence peptides are compatible with a β-sheet conformation at the interface. Structure was confirmed with PM-IRRAS and transmission FT-IR studies. The peptides show lateral miscibility with either POPC (a liquid-expanded lipid) or DPPC (a liquid-condensed lipid) in mixed peptide-lipid monolayers. This indicates that signal sequence peptides studied are laterally miscible with phospholipids independently of the phase state of the lipid.