N-acyl phosphatidylethanolamines affect the lateral distribution of cholesterol in membranes.
N-Acyl phosphatidylethanolamines are negatively charged phospholipids, which are naturally occurring albeit at low abundance. In this study, we have examined how the amide-linked acyl chain affected the membrane behavior of the N-acyl-1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylethanolamine (N-acyl-POPE) or N-acyl-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine (N-acyl-DPPE), and how the molecules interacted with cholesterol. The gel-->liquid crystalline transition temperature of sonicated N-acyl phosphatidylethanolamine vesicles in water correlated positively with the number of palmitic acyl chains in the molecules. Based on diphenylhexatriene steady state anisotropy measurements, the presence of 33 mol% cholesterol in the membranes removed the phase transition from N-oleoyl-POPE bilayers, but failed to completely remove it from N-palmitoyl-DPPE and N-palmitoyl-POPE bilayers, suggesting rather weak interaction of cholesterol with the N-saturated NAPEs. The rate of cholesterol desorption from mixed monolayers containing N-palmitoyl-DPPE and cholesterol (1:1 molar ratio) was much higher compared to cholesterol/DPPE binary monolayers, suggesting a weak cholesterol interaction with N-palmitoyl-DPPE also in monolayers. In bilayer membranes, both N-palmitoyl-POPE and N-palmitoyl-DPPE failed to form sterol-rich domains, and in fact appeared to displace sterol from sterol/N-palmitoyl-sphingomyelin domains. The present data provide new information about the effects of saturated NAPEs on the lateral distribution of cholesterol in NAPE-containing membranes. These findings may be of relevance to neural cells which accumulate NAPEs during stress and cell injury.
Térová
Bohdana
B
Department of Biochemistry and Pharmacy, Abo Akademi, Turku, Finland.
Petersen
Gitte
G
Hansen
Harald S
HS
Slotte
J Peter
JP
D002152:Calorimetry, Differential Scanning; D002784:Cholesterol / Q000737:chemistry*; D004161:Diphenylhexatriene / Q000737:chemistry; D005454:Fluorescence Polarization; D008051:Lipid Bilayers / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry*
D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; D004161:Diphenylhexatriene; C007510:1,2-dipalmitoyl-3-phosphatidylethanolamine; D002784:Cholesterol