Membrane-Perturbing Activities of KL4-Related Surfactant Peptides
KL4 is a 21-residue peptide proposed as a potential substitute of pulmonary surfactant protein SP-B in synthetic surfactants, intended for the treatment of respiratory pathologies. The peptide, composed by leucines interrupted by lysine every four residues, was synthesized to simulate C-terminal amphipathic helical segments of SP-B. Once incorporated into lipid-protein complexes, KL4 promotes formation of interfacial films that produce and maintain surface tensions below 5 mN/m during compression-expansion cycling. Although KL4 was designed as an amphipathic helix at the membrane surface, the data on orientation and interactions of the peptide in membranes are contradictory. In the present …
Interfacial behavior of recombinant forms of human pulmonary surfactant protein SP-C.
The behavior at air-liquid interfaces of two recombinant versions of human surfactant protein SP-C has been characterized in comparison with that of native palmitoylated SP-C purified from porcine lungs. Both native and recombinant proteins promoted interfacial adsorption of dipalmitoylphosphatidylcholine bilayers to a limited extent, but catalyzed very rapid formation of films from different lipid mixtures containing both zwitterionic and anionic phospholipids. Once at the interface, the recombinant variants exhibited compression-driven structural transitions, consistent with changes in the orientation of the deacylated N-terminal segment, which were not observed in the native protein. Com…
Plant virus cell-to-cell movement is not dependent on the transmembrane disposition of its movement protein
ABSTRACT The cell-to-cell transport of plant viruses depends on one or more virus-encoded movement proteins (MPs). Some MPs are integral membrane proteins that interact with the membrane of the endoplasmic reticulum, but a detailed understanding of the interaction between MPs and biological membranes has been lacking. The cell-to-cell movement of the Prunus necrotic ringspot virus (PNRSV) is facilitated by a single MP of the 30K superfamily. Here, using a myriad of biochemical and biophysical approaches, we show that the PNRSV MP contains only one hydrophobic region (HR) that interacts with the membrane interface, as opposed to being a transmembrane protein. We also show that a proline resi…