Hydrophobic Surfactant Proteins Induce a Phosphatidylethanolamine to Form Cubic Phases

Chavarha, Mariya; Khoojinian, Hamed; Schulwitz, Leonard E.; Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

doi:10.1016/j.bpj.2009.12.4302

Cited by 33 publications

(48 citation statements)

References 50 publications

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“…Those lipid-protein assemblies could be responsible for the higher ability of primed surfactant to transfer material into the interface. The fact that non-lamellar lipid organizations could mimic the structure of possible transient states during fusion of membranes with the interfacial film would support this hypothesis (50). Complementary experiments applying x-ray scattering or phosphorous NMR to HA-primed surfactant samples should provide important information to confirm the implication of possible non-lamellar phases in the ability of polymers like HA to promote surface activity.…”

Section: Discussionmentioning

confidence: 90%

“…It has been proposed, for example, that the inverted H II phase promotes interfacial surfactant adsorption (49) and that hydrophobic surfactant proteins favor highly curved lipid organizations, such as cubic and H II phases (50,51). Moreover, certain lipid systems enriched in phosphatidylethanolamine and cholesterol adopt non-lamellar phases under conditions of limited hydration (52).…”

Section: Discussionmentioning

confidence: 99%

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Transient Exposure of Pulmonary Surfactant to Hyaluronan Promotes Structural and Compositional Transformations into a Highly Active State

López-Rodríguez

Cruz

Richter

et al. 2013

Journal of Biological Chemistry

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Background: Pulmonary surfactant is inactivated under pathological conditions, making clinical surfactants fail in respiratory therapies. Results: Exposure to a hyaluronan meshwork modifies the structure and composition of surfactant. Conclusion: Transient exposure of surfactant to hyaluronan leads to a higher resistance to inactivation. Significance: Understanding the effects of polymers as additives in surfactant will allow the development of new therapeutic options.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Transient Exposure of Pulmonary Surfactant to Hyaluronan Promotes Structural and Compositional Transformations into a Highly Active State

López-Rodríguez

Cruz

Richter

et al. 2013

Journal of Biological Chemistry

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“…Extracted calf surfactant, obtained from Dr. Edmund Egan (ONY, Amherst, NY), provided the source of the hydrophobic surfactant proteins, which were separated in their physiological ratio from the surfactant lipids by gel permeation chromatography (33)(34)(35). SP-B and SP-C isolated by this procedure have the expected characteristics (36,37). SP-B migrates electrophoretically on gels as a reducible homodimer of monomers containing 79 amino acids.…”

Section: Methodsmentioning

confidence: 93%

“…for other space groups, for allowed values of the Miller indices, h, k, and l (37,40). For the hexagonal phase, the slope of these plots provided the lattice constant, a 0 , according to…”

Section: Methodsmentioning

confidence: 99%

“…The structures formed by lipids with spontaneous curvature are determined by the balance between the energies of bending and chain packing (47,48). Several peptides with amphipathic helices, including both the combined surfactant proteins (37) and isolated SP-B (36), convert lamellar lipids to Q II phases (49,50). Other peptides with similar helical elements lower the temperature of the lamellar-to-H II transition (6,11,49,51,52).…”

Section: Proteins Induce Negative Curvaturementioning

confidence: 99%

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Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature

Chavarha

Loney

Rananavare

et al. 2015

Biophysical Journal

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The hydrophobic surfactant proteins SP-B and SP-C greatly accelerate the adsorption of vesicles containing the surfactant lipids to form a film that lowers the surface tension of the air/water interface in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. As with fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, suggesting that adsorption proceeds via a rate-limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. In the studies reported here, we tested whether the surfactant proteins might promote adsorption by inducing lipids to adopt a more negative curvature, closer to the configuration of the hypothetical intermediate. Our experiments used x-ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC), the proteins produced a dose-related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With an increasing mol fraction of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w/w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Analysis of the results in terms of a Langmuir model for binding to a surface suggests that the effect of the lipids is consistent with a change in the maximum binding capacity. Our findings show that surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism.

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Structure–function correlations of pulmonary surfactant protein SP-B and the saposin-like family of proteins

2012

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Pulmonary surfactant is a lipid-protein complex secreted by the respiratory epithelium of mammalian lungs, which plays an essential role in stabilising the alveolar surface and so reducing the work of breathing. The surfactant protein SP-B is part of this complex, and is strictly required for the assembly of pulmonary surfactant and its extracellular development to form stable surface-active films at the air-liquid alveolar interface, making the lack of SP-B incompatible with life. In spite of its physiological importance, a model for the structure and the mechanism of action of SP-B is still needed. The sequence of SP-B is homologous to that of the saposin-like family of proteins, which are membrane-interacting polypeptides with apparently diverging activities, from the co-lipase action of saposins to facilitate the degradation of sphingolipids in the lysosomes to the cytolytic actions of some antibiotic proteins, such as NK-lysin and granulysin or the amoebapore of Entamoeba histolytica. Numerous studies on the interactions of these proteins with membranes have still not explained how a similar sequence and a potentially related fold can sustain such apparently different activities. In the present review, we have summarised the most relevant features of the structure, lipid-protein and protein-protein interactions of SP-B and the saposin-like family of proteins, as a basis to propose an integrated model and a common mechanistic framework of the apparent functional versatility of the saposin fold.

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Hydrophobic Surfactant Proteins Induce a Phosphatidylethanolamine to Form Cubic Phases

Cited by 33 publications

References 50 publications

Transient Exposure of Pulmonary Surfactant to Hyaluronan Promotes Structural and Compositional Transformations into a Highly Active State

Transient Exposure of Pulmonary Surfactant to Hyaluronan Promotes Structural and Compositional Transformations into a Highly Active State

Hydrophobic Surfactant Proteins Strongly Induce Negative Curvature

Structure–function correlations of pulmonary surfactant protein SP-B and the saposin-like family of proteins

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