title: Characterization and expression of attacin, an antibacterial protein-encoding gene, from the beet armyworm, Spodoptera exigua (Hübner) (Insecta: Lepidoptera: Noctuidae).
abstract: To isolate antimicrobial-related genes from the beet armyworm, Spodoptera exigua, we performed GeneFishing, a polymerase chain reaction (PCR)-based differential display technique. An attacin-like complementary DNA (cDNA) including a 3'-untranslated region was identified from among 18 over-expressed genes in microbial-infected larvae. The full-length attacin cDNA from S. exigua cDNA (Seattacin) was cloned using rapid amplification of cDNA ends PCR. The attacin-like cDNA transcript was 765 nucleotides in length, and the predicted polypeptide was 254 amino acids in length with a calculated molecular mass of 27.6 kDa and an isoelectric point of 6.44. The protein sequence of the attacin-like cDNA showed high identity to that of Trichoplusia ni (61.2%). The amino acid sequence identity of Seattacin to the orthologous proteins in Bombyx mori, Manduca sexta, Heliothis virescens, Hlicoverpa armigera, Hyphantria cunea, Hyalophora cecropia, and Drosophila melanogaster was 61.2, 46.1, 44.5, 42.2, 39.5, 45.1, and 24.0%, respectively. To examine possible immune functions of the attacin-like cDNA, its expression was investigated by reverse transcriptase PCR analysis after challenging S. exigua with microorganisms. The attacin-like cDNA was expressed at high levels 12 h post-infection, and its expression was slightly induced 4-8 h post-infection compared to control larvae inoculated with sterile water. Furthermore, induced Seattacin showed biological activity against several bacteria including Escherichia                         coli DH5α, Pseudomonas cichorii, Bacillus subtilis, and Listeria monocytogenes. These results suggest that the attacin-like cDNA of S. exigua codes for antimicrobial peptides.
authors.affiliation: Department of Applied Biology, College of Agriculture and Life Science, Agriculture and Life Sciences Research Institute, Kangwon National University, Chuncheon, 200-701, Korea.
authors.forename: Kyeongrin
authors.initials: K
authors.lastname: Bang
authors.forename: Sujin
authors.initials: S
authors.lastname: Park
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Yoo
authors.forename: Saeyoull
authors.initials: S
authors.lastname: Cho
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D027461:Beta vulgaris / Q000469:parasitology*; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D017344:Genes, Insect / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018411:Spodoptera / Q000187:drug effects / Q000235:genetics* / Q000276:immunology / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D018076:DNA, Complementary; D019476:Insect Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C039711:attacin antibacterial protein, insect