title: The first anionic defensin from amphibians.
abstract: A variety of antimicrobial peptides against infection have been identified from the skin of amphibians. However, knowledge on amphibian defensins is very limited. A novel anionic defensin designated PopuDef was purified from the skin of tree frog Polypedates puerensis, and the cDNA encoding PopuDef precursor was cloned from the skin cDNA library. The amino acid sequence of PopuDef (net charge: -2, pI: 4.75) shared the highest identity of 57 % (25/44) with the salamander defensin CFBD-1 (net charge: 0, pI: 6.14) from urodela amphibians. PopuDef showed moderate antimicrobial activities against P. aeruginosa and S. aureus (MICs are 19.41 and 17.25 μM, respectively), and relatively weak activities against E. coli and B. subtilis (MICs are 38.82 and 43.14 μM, respectively). Tissue distribution analysis indicated that relatively high expression level of PopuDef mRNA was observed in immune-related tissues including skin, gut, lung and spleen. Furthermore, the expression level of PopuDef was significantly upregulated in these tissues after tree frogs were infected with different bacteria strains mentioned above. Interestingly, the induction of PopuDef challenged with E. coli or B. subtilis, which was less sensitive to PopuDef, was much higher than that did with P. aeruginosa or S. aureus. These findings highlight the key role of PopuDef in innate immunity against infection. To our knowledge, PopuDef is the first anionic defensin characterized from amphibians.
authors: Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu, China.
authors: Lin
authors: L
authors: Wei
authors: Helong
authors: H
authors: Che
authors: Yi
authors: Y
authors: Han
authors: Jing
authors: J
authors: Lv
authors: Lixian
authors: L
authors: Mu
authors: Lechun
authors: L
authors: Lv
authors: Jing
authors: J
authors: Wu
authors: Hailong
authors: H
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001001:Anura / Q000378:metabolism*; D001412:Bacillus subtilis / Q000187:drug effects; D001483:Base Sequence; D003001:Cloning, Molecular; D023082:Defensins / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects; D015870:Gene Expression; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D029845:Amphibian Proteins; D000900:Anti-Bacterial Agents; D023082:Defensins