title: Functional analysis of an alpha-helical antimicrobial peptide derived from a novel mouse defensin-like gene.
abstract: Gene-encoded antimicrobial peptides (AMPs) are an essential component of the innate immune system in many species. Analysis of beta-defensin gene expression in mouse tissue using primers that were specific for conserved sequences located outside of the beta-defensin translated region identified a novel small gene. The novel gene had an open reading frame of 114bp and encoded a predicted protein of 37 amino acid residues. A search of the genome database revealed that the gene locus and the sequence of exon 1 of this novel gene were similar to subgroup 1 mouse beta-defensins. A small peptide, K17 (FSPQMLQDIIEKKTKIL), derived from the amino acid sequence of this novel gene was synthesized. Circular dichroism (CD) spectroscopic analysis of chemically synthesized peptide demonstrated that the peptide exhibited random coil conformation in aqueous solution, but the peptide adopted helical conformation in the presence of trifluoroethanol or sodium dodecyl sulfate, a membrane-mimicking environment. The peptide exhibited bactericidal activity against Salmonella enterica serovar Typhimurium (Gram negative) and Staphylococcus aureus (Gram positive); it was not cytotoxic in cultures of mammalian cells or hemolytic in cultures of erythrocytes. These results suggested that K17 may be a candidate therapeutic for the treatment of bacterial infection.
authors.affiliation: Department of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kawaguchi
authors.forename: Tadaki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Takashi
authors.initials: T
authors.lastname: Kimura
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakai
authors.forename: Tokiyoshi
authors.initials: T
authors.lastname: Ayabe
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Sawa
authors.forename: Hideki
authors.initials: H
authors.lastname: Hasegawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D004912:Erythrocytes / Q000187:drug effects; D005091:Exons; D006461:Hemolysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D012486:Salmonella typhimurium / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D023083:beta-Defensins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology*
chemical_list: C551850:FSPQMLQDIIEKKTKIL; D010446:Peptide Fragments; D023083:beta-Defensins