N-nervonoylsphingomyelin (c24:1) prevents lateral heterogeneity in cholesterol-containing membranes

S.MATÉ; J. BUSTO; A.GARCÍA-ARRIBAS; J. SOT; R. VAZQUEZ; V. HERLAX; C. WOLF; L. BAKÁS; F.M, GOÑI

BIOPHYSICAL JOURNAL

CELL PRESS

Lugar: United States; Año: 2014 vol. 106 p. 2606 - 2616

0006-3495

This study was conducted to explore how the nature of the acyl chains of sphingomyelin (SM) influence its lateral distribution in the ternary lipid mixture made of SM/cholesterol/ 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), focusing on the importance of the hydrophobic part of the SM molecule for domain formation. AFMforce spectroscopy measurements showed that the presence of the double bound in the 24:1Δ15SM molecule, in mixtures with cholesterol (CHO) or in pure bilayers, led to a decrease in the molecular packing. Confocal and atomic force microscopy (AFM) showed, at meso and nanoscale respectively, that unlike 16:0 and 24:0SM 24:1SM does not induce phase segregation in ternary lipid mixtures with DOPC and CHO. This ternary lipid mixture had a nanomechanical stability intermediate between those displayed by liquid-ordered (Lo) and liquid-disordered (Ld) phases, as reported by AFM-force spectroscopy measurements, evidencing that 24:1SM is able to accommodate both DOPC and CHO, forming a single phase. Confocal experiments on giant unilamellar vesicles made of human, sheep and rabbit erythrocyte ghosts rich in 24:1SM and CHO, showed no lateral domain segregation. This study provides insights on how the specific molecular structure of SM affects the lateral behavior and the physical properties of both model and natural membranes.