title: Characterization of a chimeric antimicrobial peptide uncovers evolutionary significance of exon-shuffling.
abstract: The abaecin family comprises a class of proline-rich antimicrobial peptides (AMPs) with restricted distribution in hymenopteran insects. Intriguingly, in the parasitic wasp Nasonia vitripennis its members (termed nabaecin-1 to -3) have gained a carboxyl terminal glycine-rich antimicrobial unit through exon-shuffling. Here, we describe cDNA cloning of nabaecin-3 and the donor gene (navitripenicin) of the shuffling, and structural and functional features of nabaecin-3 and its two domains (respectively called amino-terminal abaecin unit (NtAU) and carboxyl-terminal navitripenicin unit (CtNU)). Nabaecin-3 and navitripenicin were found to be transcriptionally up-regulated in response to bacterial challenge. By using recombinant expression and chemical synthesis techniques, we produced nabaecin-3, NtAU and CtNU. Circular dichroism (CD) analyses show that these peptides remarkably differ in their structures. Functionally, nabaecin-3 displayed a wide spectrum of antimicrobial activity against an array of bacteria, yeasts and fungi at micromolar concentrations, while CtNU only had a weak antibacterial activity and NtAU completely lacked activity. Our results indicate that in Nasonia the antimicrobial function of abaecin depends on the combination of NtAU with CtNU and thus suggest a new role of exon-shuffling in buffering loss-of-function mutation of a gene.
authors.affiliation: Group of Animal Innate Immunity, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, 100101 Beijing, China.
authors.forename: Kuanyu
authors.initials: K
authors.lastname: Zhu
authors.forename: Bin
authors.initials: B
authors.lastname: Gao
authors.forename: Shunyi
authors.initials: S
authors.lastname: Zhu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D003001:Cloning, Molecular; D032621:DNA Shuffling; D019143:Evolution, Molecular; D005091:Exons / Q000235:genetics; D005658:Fungi / Q000187:drug effects; D006927:Hymenoptera / Q000235:genetics*; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology
chemical_list: D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; D011993:Recombinant Fusion Proteins; C579074:nabaecin-3, Nasonia vitripennis; C579075:navitripenicin, Nasonia vitripennis; C062933:abaecin protein, Apis mellifera