WILKE NATALIA
Congresos y reuniones científicas
Título:
The interfacial properties of the peptide polybia-mp1 and its interaction with dppc are modulated by lateral electrostatic attractions
Autor/es:
D. DOS SANTOS ALVARES, M.L. FANANI, N. WILKE, J. RUGGIERO NETO.
Lugar:
Pueryo Iguazu
Reunión:
Congreso; 56th International Conference on the Bioscience of lipids; 2015
Resumen:
Polybia-MP1 (IDWKKLLDAAKQIL-NH2), extracted from the Brazilian wasp Polybia paulista, exhibits a broadspectrum
bactericidal activity without being hemolytic and cytotoxic. In the present study, we analyzed the surface
properties of the peptide and its interactionwith DPPC in Langmuir monolayers. Polybia-MP1 formed stable
monolayers, with lateral areas and surface potential values suggesting a mostly α-helical structure oriented near
perpendicular to the membrane plane. In DPPC?peptide mixed monolayers, MP1 co-crystallized with the lipid
forming branched domains only when the subphasewas purewater. On subphaseswith high salt concentrations
or at acidic or basic conditions, the peptide formed less densely packed films andwas excluded fromthe domains,
indicating the presence of attractive electrostatic interactions between peptides, which allow them to get closer
to each other and to interact with DPPC probably as a consequence of a particular peptide arrangement. The residues
responsible of the peptide?peptide attraction are suggested to be the anionic aspartic acids and the cationic
lysines,which form a salt bridge, leading to oriented interactions in the crystal and thereby to branched domains.
For this peptide, the balance between total attractive and repulsive interactions may be finely tuned by the aqueous
ionic strength and pH, and since this effect is related with lysines and aspartic acids, similar effects may also
occur in other peptides containing these residues in their sequences.
bactericidal activity without being hemolytic and cytotoxic. In the present study, we analyzed the surface
properties of the peptide and its interactionwith DPPC in Langmuir monolayers. Polybia-MP1 formed stable
monolayers, with lateral areas and surface potential values suggesting a mostly α-helical structure oriented near
perpendicular to the membrane plane. In DPPC?peptide mixed monolayers, MP1 co-crystallized with the lipid
forming branched domains only when the subphasewas purewater. On subphaseswith high salt concentrations
or at acidic or basic conditions, the peptide formed less densely packed films andwas excluded fromthe domains,
indicating the presence of attractive electrostatic interactions between peptides, which allow them to get closer
to each other and to interact with DPPC probably as a consequence of a particular peptide arrangement. The residues
responsible of the peptide?peptide attraction are suggested to be the anionic aspartic acids and the cationic
lysines,which form a salt bridge, leading to oriented interactions in the crystal and thereby to branched domains.
For this peptide, the balance between total attractive and repulsive interactions may be finely tuned by the aqueous
ionic strength and pH, and since this effect is related with lysines and aspartic acids, similar effects may also
occur in other peptides containing these residues in their sequences.
