title: Structural and Dynamic Insights of the Interaction between Tritrpticin and Micelles: An NMR Study.
abstract: A large number of antimicrobial peptides (AMPs) acts with high selectivity and specificity through interactions with membrane lipid components. These peptides undergo complex conformational changes in solution; upon binding to an interface, one major conformation is stabilized. Here we describe a study of the interaction between tritrpticin (TRP3), a cathelicidin AMP, and micelles of different chemical composition. The peptide's structure and dynamics were examined using one-dimensional and two-dimensional NMR. Our data showed that the interaction occurred by conformational selection and the peptide acquired similar structures in all systems studied, despite differences in detergent headgroup charge or dipole orientation. Fluorescence and paramagnetic relaxation enhancement experiments showed that the peptide is located in the interface region and is slightly more deeply inserted in 1-myristoyl-2-hydroxy-sn-glycero-3-phospho-1'-rac-glycerol (LMPG, anionic) than in 1-lauroyl-2-hydroxy-sn-glycero-3-phosphocholine (LLPC, zwitterionic) micelles. Moreover, the tilt angle of an assumed helical portion of the peptide is similar in both systems. In previous work we proposed that TRP3 acts by a toroidal pore mechanism. In view of the high hydrophobic core exposure, hydration, and curvature presented by micelles, the conformation of TRP3 in these systems could be related to the peptide's conformation in the toroidal pore.
authors.affiliation: Nuclear Magnetic Resonance National Center, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Talita L
authors.initials: TL
authors.lastname: Santos
authors.affiliation: Department of Chemistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Moraes
authors.affiliation: Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Clovis R
authors.initials: CR
authors.lastname: Nakaie
authors.affiliation: Nuclear Magnetic Resonance National Center, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fabio C L
authors.initials: FC
authors.lastname: Almeida
authors.affiliation: Department of Biochemistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Shirley
authors.initials: S
authors.lastname: Schreier
authors.affiliation: Nuclear Magnetic Resonance National Center, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: valente@cnrmn.bioqmed.ufrj.br.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Valente
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism*; D055550:Protein Stability
chemical_list: D008823:Micelles; D009842:Oligopeptides; C402895:tritrpticin