Lipid and peptide specificities in signal peptide--lipid interactions in model membranes.
The present data show the critical importance of the anionic lipid content in monomolecular layers for the interaction with PhoE signal peptide. At 37 degrees C and 100 mM NaCl the interaction is maximal at 30-40 mol% anionic lipid. The results correlate with the reduced translocation competence of Escherichia coli strain HD3122, which has a much lower anionic lipid content as compared to the wild-type strain SD12 (De Vrije et al. (1988) Nature 334, 173-175). PhoE signal peptide analogs as N-formyl PhoE signal peptide, PhoE signal peptide +(1-7) and PhoE signal peptide Val-8----Trp-8 show the same lipid preference as PhoE signal peptide. On the other hand the affinity for an anionic lipid interface is strongly reduced for PhoE signal peptide Lys-19,-20----Asp-19,-20, which correlates with the less efficient translocation of PhoE protein carrying this signal sequence. At limiting anionic lipid concentrations there is a temperature and salt effect on the observed interaction, which is related to a conformational change of the peptide. Signal sequences show clearly conformational flexibility in responds to environmental conditions. Under the conditions used in this study FTIR spectra of PhoE signal peptide-DOPG monolayers show a high content of beta-structure and beta-turn.
Demel
R A
RA
Centre for Biomembranes and Lipid Enzymology, University of Utrecht, The Netherlands.
Goormaghtigh
E
E
de Kruijff
B
B
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008081:Liposomes; D008954:Models, Biological; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000138:chemical synthesis; D018272:Porins; D011312:Pressure; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism*; D013499:Surface Properties; D013816:Thermodynamics
D001425:Bacterial Outer Membrane Proteins; D008081:Liposomes; D010743:Phospholipids; D018272:Porins; D021382:Protein Sorting Signals