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Folding of lipid monolayers containing lung surfactant proteins SP-B1 – 25 and SP-C studied via coarse-grained molecular dynamics simulations
- Source :
-
BBA: Biomembranes . Sep2010, Vol. 1798 Issue 9, p1632-1650. 19p. - Publication Year :
- 2010
-
Abstract
- Abstract: To explore the role of lung surfactant proteins SP-B and SP-C in storing and redelivering lipid from lipid monolayers during the compression and re-expansion occurring in lungs during breathing, we simulate the folding of lipid monolayers with and without these proteins. We utilize the MARTINI coarse-grained force field to simulate monolayers containing pure dipalmitoylphosphatidylcholine (DPPC) and DPPC mixed with palmitoyloleoylphosphatidylglycerol (POPG), palmitic acid (PA), and/or peptides. The peptides considered include the 25-residue N-terminal fragment of SP-B (SP-B1 – 25), SP-C, and several SP-B1 – 25 mutants in which charged and hydrophilic residues are replaced by hydrophobic ones, or vice-versa. We observe two folding mechanisms: folding by the amplification of undulations and folding by nucleation about a defect. The first mechanism is observed in monolayers containing either POPG or peptides, while the second mechanism is observed only with peptides present, and involves the lipid-mediated aggregation of the peptides into a defect, from which the fold can nucleate. Fold nucleation from a defect displays a dependence on the hydrophobic character of the peptides; if the number of hydrophobic residues is decreased significantly, monolayer folding does not occur. The addition of POPG or peptides to the DPPC monolayer has a fluidizing effect, which assists monolayer folding. In contrast, the addition of PA has a charge-dependent condensing affect on DPPC monolayers containing SP-C. The peptides appear to play a significant role in the folding process, and provide a larger driving force for folding than POPG. In addition to promoting fold formation, the peptides also display fusogenic behavior, which can lead to surface refining. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00052736
- Volume :
- 1798
- Issue :
- 9
- Database :
- Academic Search Index
- Journal :
- BBA: Biomembranes
- Publication Type :
- Academic Journal
- Accession number :
- 52306586
- Full Text :
- https://doi.org/10.1016/j.bbamem.2010.04.006