title: Generation of novel cationic antimicrobial peptides from natural non-antimicrobial sequences by acid-amide substitution.
abstract: BACKGROUND
  Cationic antimicrobial peptides (CAMPs) are well recognized to be promising as novel antimicrobial and antitumor agents. To obtain novel skeletons of CAMPs, we propose a simple strategy using acid-amide substitution (i.e. Glu→Gln, Asp→Asn) to confer net positive charge to natural non-antimicrobial sequences that have structures distinct from known CAMPs. The potential of this strategy was verified by a trial study.
  
  
  METHODS
  The pro-regions of nematode cecropin P1-P3 (P1P-P3P) were selected as parent sequences. P1P-P3P and their acid-amide-substituted mutants (NP1P-NP3P) were chemically synthesized. Bactericidal and membrane-disruptive activities of these peptides were evaluated. Conformational changes were estimated from far-ultraviolet circular dichroism (CD) spectra.
  
  
  RESULTS
  NP1P-NP3P acquired potent bactericidal activities via membrane-disruption although P1P-P3P were not antimicrobial. Far-ultraviolet CD spectra of NP1P-NP3P were similar to those of their parent peptides P1P-P3P, suggesting that NP1P-NP3P acquire microbicidal activity without remarkable conformational changes. NP1P-NP3P killed bacteria in almost parallel fashion with their membrane-disruptive activities, suggesting that the mode of action of those peptides was membrane-disruption. Interestingly, membrane-disruptive activity of NP1P-NP3P were highly diversified against acidic liposomes, indicating that the acid-amide-substituted nematode cecropin pro-region was expected to be a unique and promising skeleton for novel synthetic CAMPs with diversified membrane-discriminative properties.
  
  
  CONCLUSIONS
  The acid-amide substitution successfully generated some novel CAMPs in our trial study. These novel CAMPs were derived from natural non-antimicrobial sequences, and their sequences were completely distinct from any categories of known CAMPs, suggesting that such mutated natural sequences could be a promising source of novel skeletons of CAMPs.
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan. kato@affrc.go.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ueno
authors.forename: Masaomi
authors.initials: M
authors.lastname: Minaba
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishiuchi
authors.forename: Misako
authors.initials: M
authors.lastname: Taichi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Tamada
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kato
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D010455:Peptides; C070016:cecropin P1-LI