title: Alarin but not its alternative-splicing form, GALP (Galanin-like peptide) has antimicrobial activity.
abstract: Alarin is an alternative-splicing form of GALP (galanin-like peptide). It shares only 5 conserved amino acids at the N-terminal region with GALP which is involved in a diverse range of normal brain functions. This study seeks to investigate whether alarin has additional functions due to its differences from GALP. Here, we have shown using a radial diffusion assay that alarin but not GALP inhibited the growth of Escherichia coli (strain ML-35). The conserved N-terminal region, however, remained essential for the antimicrobial activity of alarin as truncated peptides showed reduced killing effect. Moreover, alarin inhibited the growth of E. coli in a similar potency as human cathelicidin LL-37, a well-studied antimicrobial peptide. Electron microscopy further showed that alarin induced bacterial membrane blebbing but unlike LL-37, it did not cause hemolysis of erythrocytes. In addition, alarin is only active against the gram-negative bacteria, E. coli but not the gram-positive bacteria, Staphylococcus aureus. Thus, these data suggest that alarin has potentials as an antimicrobial and should be considered for the development in human therapeutics.
authors.affiliation: Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 8528523, Japan. a-wada@nagasaki-u.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Wada
authors.forename: Pooi-Fong
authors.initials: PF
authors.lastname: Wong
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hojo
authors.forename: Makoto
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Akitoyo
authors.initials: A
authors.lastname: Ichinose
authors.forename: Rafael
authors.initials: R
authors.lastname: Llanes
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Kubo
authors.forename: Masachika
authors.initials: M
authors.lastname: Senba
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ichinose
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D044089:Galanin-Like Peptide / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006461:Hemolysis; D006736:Horses / Q000097:blood; D006801:Humans; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; D044089:Galanin-Like Peptide; C581934:alarin