title: The effects of the C-terminal amidation of mastoparans on their biological actions and interactions with membrane-mimetic systems.
abstract: Polycationic peptides may present their C-termini in either amidated or acidic form; however, the effects of these conformations on the mechanisms of interaction with the membranes in general were not properly investigated up to now. Protonectarina-MP mastoparan with an either amidated or acidic C-terminus was utilized to study their interactions with anionic and zwitterionic vesicles, using measurements of dye leakage and a combination of H/D exchange and mass spectrometry to monitor peptide-membrane interactions. Mast cell degranulation, hemolysis and antibiosis assays were also performed using these peptides, and the results were correlated with the structural properties of the peptides. The C-terminal amidation promotes the stabilization of the secondary structure of the peptide, with a relatively high content of helical conformations, permitting a deeper interaction with the phospholipid constituents of animal and bacterial cell membranes. The results suggested that at low concentrations Protonectarina-MP interacts with the membranes in a way that both terminal regions remain positioned outside the external surface of the membrane, while the α-carbon backbone becomes partially embedded in the membrane core and changing constantly the conformation, and causing membrane destabilization. The amidation of the C-terminal residue appears to be responsible for the stabilization of the peptide conformation in a secondary structure that is richer in α-helix content than its acidic congener. The helical, amphipathic conformation, in turn, allows a deeper peptide-membrane interaction, favoring both biological activities that depend on peptide structure recognition by the GPCRs (such as exocytosis) and those activities dependent on membrane perturbation (such as hemolysis and antibiosis).
authors: Institute of Biosciences of Rio Claro, Universidade Estadual Paulista (UNESP), C.E.I.S./Department of Biology, Rio Claro, SP, Brazil.
authors: Alessandra V R
authors: AV
authors: da Silva
authors: Institute of Biosciences of Rio Claro, Universidade Estadual Paulista (UNESP), C.E.I.S./Department of Biology, Rio Claro, SP, Brazil.
authors: Bibiana M
authors: BM
authors: De Souza
authors: IBILCE - Universidade Estadual Paulista (UNESP), Department of Chemistry and Environmental Sciences, São José do Rio Preto, SP, Brazil.
authors: Marcia P
authors: MP
authors: Dos Santos Cabrera
authors: Institute of Biosciences of Rio Claro, Universidade Estadual Paulista (UNESP), C.E.I.S./Department of Biology, Rio Claro, SP, Brazil.
authors: Nathalia B
authors: NB
authors: Dias
authors: Institute of Biosciences of Rio Claro, Universidade Estadual Paulista (UNESP), C.E.I.S./Department of Biology, Rio Claro, SP, Brazil.
authors: Paulo C
authors: PC
authors: Gomes
authors: IBILCE - Universidade Estadual Paulista (UNESP), Campus of São José do Rio Preto, Department of Physics, São José do Rio Preto, SP, Brazil.
authors: João Ruggiero
authors: JR
authors: Neto
authors: CEBio, Núcleo de Saúde (NUSAU), Universidade Federal de Rondônia (UNIR), Porto Velho, RO, Brazil.
authors: Rodrigo G
authors: RG
authors: Stabeli
authors: Institute of Biosciences of Rio Claro, Universidade Estadual Paulista (UNESP), C.E.I.S./Department of Biology, Rio Claro, SP, Brazil. Electronic address: mspalma@rc.unesp.br.
authors: Mario S
authors: MS
authors: Palma
mesh_terms: D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005260:Female; D036341:Intercellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D008567:Membranes, Artificial; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar; D014862:Wasp Venoms / Q000737:chemistry / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D008567:Membranes, Artificial; D010455:Peptides; D014862:Wasp Venoms; C037500:mastoparan
keywords: Antimicrobial peptide; H/D exchange; Mass spectrometry; Mastoparan; Peptide–membrane interaction; Peptidomics