title: Design, structural and functional characterization of a Temporin-1b analog active against Gram-negative bacteria.
abstract: BACKGROUND
  Temporins are small antimicrobial peptides secreted by the Rana temporaria showing mainly activity against Gram-positive bacteria. However, different members of the temporin family, such as Temporin B, act in synergy also against Gram-negative bacteria. With the aim to develop a peptide with a wide spectrum of antimicrobial activity we designed and analyzed a series of Temporin B analogs.
  
  
  METHODS
  Peptides were initially obtained by Ala scanning on Temporin B sequence; antimicrobial activity tests allowed to identify the TB_G6A sequence, which was further optimized by increasing the peptide positive charge (TB_KKG6A). Interactions of this active peptide with the LPS of E. coli were investigated by CD, fluorescence and NMR.
  
  
  RESULTS
  TB_KKG6A is active against Gram-positive and Gram-negative bacteria at low concentrations. The peptide strongly interacts with the LPS of Gram-negative bacteria and folds upon interaction into a kinked helix.
  
  
  CONCLUSIONS
  Our results show that it is possible to widen the activity spectrum of an antimicrobial peptide by subtle changes of the primary structure. TB_KKG6A, having a simple composition, a broad spectrum of antimicrobial activity and a very low hemolytic activity, is a promising candidate for the design of novel antimicrobial peptides.
  
  
  CONCLUSIONS
  The activity of antimicrobial peptides is strongly related to the ability of the peptide to interact and break the bacterial membrane. Our studies on TB_KKG6A indicate that efficient interactions with LPS can be achieved when the peptide is not perfectly amphipathic, since this feature seems to help the toroidal pore formation process.
authors: Università di Napoli Federico II, Dipartimento delle Scienze Biologiche, Napoli, Italy.
authors: Concetta
authors: C
authors: Avitabile
authors: Fortuna
authors: F
authors: Netti
authors: Giuseppina
authors: G
authors: Orefice
authors: Maddalena
authors: M
authors: Palmieri
authors: Nunzia
authors: N
authors: Nocerino
authors: Gaetano
authors: G
authors: Malgieri
authors: Luca D
authors: LD
authors: D'Andrea
authors: Rosanna
authors: R
authors: Capparelli
authors: Roberto
authors: R
authors: Fattorusso
authors: Alessandra
authors: A
authors: Romanelli
mesh_terms: D029845:Amphibian Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D015195:Drug Design; D004926:Escherichia coli / Q000254:growth & development*; D011506:Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D011896:Rana temporaria
chemical_list: D029845:Amphibian Proteins; D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D011506:Proteins; C104501:temporin