Aggregatibacter actinomycetemcomitans leukotoxin cytotoxicity occurs through bilayer destabilization

摘要: The Gram-negative bacterium, Aggregatibacter actinomycetemcomitans, is a common inhabitant of the human upper aerodigestive tract. organism produces an RTX (Repeats in ToXin) toxin (LtxA) that kills white blood cells. LtxA believed to be membrane-damaging toxin, but details cell surface interaction for this and several other toxins have yet elucidated. Initial morphological studies suggested was bending target membrane. Because ability membrane bend function its lipid composition, we assessed proficiency release fluorescent dye from panel liposomes composed various lipids. Liposomes lipids form nonlamellar phases were susceptible LtxA-induced damage while do not non-bilayer structures not. Differential scanning calorimetry demonstrated decreased temperature at which transitions bilayer phase, (31) P nuclear magnetic resonance showed transition inverted hexagonal phase occurs through formation isotropic intermediate phase. These results indicate cytotoxicity process destabilization.