Structural and functional importance of the C-terminal part of the pulmonary surfactant polypeptide SP-C.
A synthetic non-palmitoylated form of the pulmonary surfactant protein SP-C and three peptides of different lengths corresponding to its N-terminal and middle parts were reconstituted into dipalmitoylglycerophosphocholine/phosphatidylglycerol (7:3, by mass) lipid bilayers. The adsorption properties of each reconstituted system were determined by measurement of the surface pressure after injection of the samples underneath an air/water interface. Attenuated total reflection infrared spectroscopy provided information about the structure and orientation of peptides in lipid bilayers. The hydrophobic C-terminal helix is crucial for the rapid adsorption as shortening of the C-terminal part drastically restricted this activity. The C-terminal amino acid sequence can however be replaced with that of the second transmembrane helix of bacteriorhodopsin without significantly modifying the adsorption properties. The data suggest that the hydrophobic C-terminal part allows the anchorage of SP-C in the lipid bilayer in such a manner that the N-terminal domain adopts an optimal conformation and orientation for the rapid adsorption of phospholipids at the air/water interface, and/or that a membrane-spanning helix as such is needed for this activity.
Clercx
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Service de Néonatologie, Hôpital des Enfants Reine Fabiola, Université Libre de Bruxelles, Belgium.
Vandenbussche
G
G
Curstedt
T
T
Johansson
J
J
Jörnvall
H
H
Ruysschaert
J M
JM
D000327:Adsorption; D000595:Amino Acid Sequence; D000818:Animals; D066298:In Vitro Techniques; D008051:Lipid Bilayers; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D017433:Protein Structure, Secondary; D011510:Proteolipids / Q000737:chemistry*; D011663:Pulmonary Surfactants / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship; D013552:Swine
D008051:Lipid Bilayers; D010455:Peptides; D010743:Phospholipids; D011510:Proteolipids; D011663:Pulmonary Surfactants