title: cDNA cloning and characterization of the antibacterial peptide cecropin 1 from the diamondback moth, Plutella xylostella L.
abstract: Cecropins are linear cationic antibacterial peptides that have potent activities against microorganisms. In the present study, a 480bp full-length cDNA encoding diamondback moth (Plutella xylostella) cecropin 1 (designated as Px-cec1) was obtained using RT-PCR. A Northern blot analysis showed that the Px-cec1 transcript was predominantly expressed in fat bodies, hemocytes, midgut and epidermis with the highest expression level in fat bodies. The expression of Px-cec1 mRNA in fat bodies was significantly increased 24h after microbial challenge, with the highest induced expression by Staphylococcus aureus. A circular dichroism (CD) analysis revealed that the recombinant Px-cec1 mainly contained α-helixes. Antimicrobial assays demonstrated that recombinant Px-cec1 exhibited a broad spectrum of anti-microbial properties against fungi, Gram-positive and Gram-negative bacteria, but it did not exhibit hemolytic activity against human erythrocytes. Furthermore, Px-cec1 caused significant morphological alterations of S. aureus, as shown by scanning electron microscopy and transmission electron microscopy. These results demonstrated that Px-cec1 exerts its antibacterial activity by acting on the cell membrane to disrupt bacterial cell structures.
authors.affiliation: College of Natural Resources and Environments, South China Agricultural University, Engineering Research Center of Biological Control, Ministry of Education, Guangzhou, China. jflbang@yahoo.com.cn
authors.forename: Fengliang
authors.initials: F
authors.lastname: Jin
authors.forename: Qiang
authors.initials: Q
authors.lastname: Sun
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Xu
authors.forename: Linmiao
authors.initials: L
authors.lastname: Li
authors.forename: Gang
authors.initials: G
authors.lastname: Gao
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Xu
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Yu
authors.forename: Shunxiang
authors.initials: S
authors.lastname: Ren
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D001483:Base Sequence; D054807:Cecropins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D048430:Cell Shape; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004912:Erythrocytes; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D008853:Microscopy; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D009928:Organ Specificity; D010802:Phylogeny; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D016415:Sequence Alignment; D013057:Spectrum Analysis
chemical_list: D000900:Anti-Bacterial Agents; D054807:Cecropins; D018076:DNA, Complementary; D019476:Insect Proteins; D011994:Recombinant Proteins