Surfactant protein SP-B strongly modifies surface collapse of phospholipid vesicles: insights from a quartz crystal microbalance with dissipation.
Pulmonary surfactant protein B (SP-B) facilitates the rapid transfer of phospholipids from bilayer stores into air-liquid interfacial films along the breathing cycle, and contributes to the formation of a surface-associated multilayer reservoir of surfactant to optimize the stability of the respiratory interface. To obtain more insights into the mechanisms underlying this transfer and multilayer formation, we established a simple model system that captures different features of SP-B action. We monitored the formation of supported planar bilayers from the collapse of intact phospholipid vesicles on a silica surface using a technique called quartz crystal microbalance with dissipation, which provides information on changes in membrane thickness and viscosity. At physiologically relevant concentrations, SP-B dramatically alters vesicle collapse. This manifests itself as a reduced buildup of intact vesicles on the surface before collapse, and allows the stepwise buildup of multilayered deposits. Accumulation of lipids in these multilayer deposits requires the presence of SP-B in both the receptor and the arriving membranes, surrounded by a comparable phospholipid charge. Thus, the quartz crystal microbalance with dissipation system provides a useful, simplified way to mimic the effect of surfactant protein on vesicle dynamics and permits a detailed characterization of the parameters governing reorganization of surfactant layers.
Cabré
Elisa J
EJ
Departamento Bioquímica y Biología Molecular I, Facultad de Biología, Universidad Complutense, Madrid, Spain.
Malmström
Jenny
J
Sutherland
Duncan
D
Pérez-Gil
J
J
Otzen
Daniel E
DE
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000818:Animals; D003584:Cytological Techniques / Q000379:methods; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D037701:Pulmonary Surfactant-Associated Protein B / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013552:Swine; D053835:Unilamellar Liposomes / Q000737:chemistry*
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D010743:Phospholipids; D037701:Pulmonary Surfactant-Associated Protein B; D053835:Unilamellar Liposomes; D015060:1,2-Dipalmitoylphosphatidylcholine; D012822:Silicon Dioxide; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C017251:1,2-oleoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine