Interactions of metal ions with phosphatidylserine bilayer membranes: effect of hydrocarbon chain unsaturation

Abstract

A combination of surface monolayer, scanning calorimetry, 31P NMR, and spin-label ESR techniques has been used to monitor the interactions of monovalent (NH4+, Na+, and Li+) and divalent (Ca2+) cations with phosphatidylserines (PS) differing in their levels of chain unsaturation. Comparisons are made between the disaturated dimyristoyl-, dipalmitoyl-, and dihexadecyl-PS (DMPS, DPPS, and DHPS), saturated cis-monounsaturated palmitoyloleoyl-PS (POPS) (and bovine brain PS), di-trans-monounsaturated dielaidoyl-PS (DEPS), and di-cis-monounsaturated dioleoyl-PS (DOPS). Na+ and NH4+ cations interact weakly with all PS monolayers and bilayers without significant changes in molecular conformation, chain packing, or headgroup dynamics and without dependence on chain composition. In contrast, considering these structural and dynamic parameters, Li+ shows a gradation in its interaction with PS (DMPS greater than POPS approximately bovine brain PS greater than DOPS), suggesting that Li+-PS interactions depend on the interfacial properties of the PS molecules (e.g., surface area). Finally, Ca2+ interacts strongly with all PS monolayers and bilayers, without obvious chain selectivity. Thus, ion binding to PS depends not only on the properties of the cation (Na+ vs Li+ vs Ca2+) but also on the molecular details of the PS membrane surface.

Modulation of the Interaction between Neurotensin Receptor NTS1 and Gq Protein by Lipid

“…We utilized the zwitterionic POPC and negatively charged POPG, both of which have phase transition temperatures below 0°C 40,41 and a cylindrical molecular shape 42 . POPG (although a minor phospholipid in eukaryotic membranes 42 ) was chosen instead of the more abundant 1-palmitoyl-2-oleoyl- sn -glycero-3-phospho-L-serine with a higher transition temperature of 14°C 43 . All nanodisc reconstitution experiments were conducted using either zwitterionic POPC, a mixture of POPC/POPG at a molar ratio of 1:1, or negatively charged POPG.…”

Negatively Charged Lipids as a Potential Target for New Amphiphilic Aminoglycoside Antibiotics

“…The proposed mechanism involves reduced repulsion and a dehydration of lipid headgroups (65,66) and an increase of membrane tension (67) in the outer leaflet (68). The hemifusion intermediate could directly lead to the formation of a pore, or it might expand radially into a hemifusion diaphragm with the distal membrane leaflets remaining separated and a bilayer formed by the inner monolayers for both vesicles (62).…”

Na+ and Ca2+ Effect on the Hydration and Orientation of the Phosphate Group of DPPC at Air−Water and Air−Hydrated Silica Interfaces

“…Yet the knowledge of the interaction between monovalent ions and phospholipids is less detailed apart from theoretical work. [13][14][15][16][17] Divalent cations such as calcium ions are known to interact strongly with charged lipids but only moderately with zwitterionic lipids, 5, 6,[9][10][11][18][19][20] yet experimental studies that provide molecular insights of this interaction have also remained limited. 21 Molecular information of this binding process has been explored by theoretical studies, although these reports are usually restricted to a single area per molecule (lipid phase).…”