1. Sequence characterization and expression patterns of two defensin-like antimicrobial peptides from the tick Haemaphysalis longicornis
Jinlin Zhou, Min Liao, Mami Ueda, Haiyan Gong, Xuenan Xuan, Kozo Fujisaki Peptides. 2007 Jun;28(6):1304-10. doi: 10.1016/j.peptides.2007.04.019. Epub 2007 May 6.
Two cDNAs encoding defensin-like antimicrobial peptides were cloned and sequenced from the tick Haemaphysalis longicornis. The full-length cDNA of Hlgut-defensin (H. longicornis midgut defensin) is 333bp, encoding an expected protein with 73 amino acids. The full-length cDNA of Hlsal-defensin (H. longicornis salivary gland defensin) is 382bp, encoding an expected protein with 81 amino acids. The antibacterial activities of the synthetic peptides based on the Hlgut-defensin and Hlsal-defensin sequences were tested against a variety of Gram-positive and Gram-negative bacteria. Using real-time PCR, the tissue-specific expression of two defensin-like peptides were determined and it was also found that the gene transcripts of Hlgut-defensin and Hlsal-defensin were significantly induced by a lipopolysaccharide (LPS) injection.
2. A defensin-like antimicrobial peptide from the venoms of spider, Ornithoctonus hainana
Hongwen Zhao, Yi Kong, Hanjin Wang, Tianhua Yan, Feifei Feng, Jianmin Bian, Yan Yang, Haining Yu J Pept Sci. 2011 Jul;17(7):540-4. doi: 10.1002/psc.1370. Epub 2011 Apr 28.
The defensin-like antimicrobial peptides have been characterized from various other arthropods including insects, scorpions, and ticks. But no natural spider defensin-like antimicrobial peptides have ever been isolated from spiders, except couple of cDNA and DNA sequences of five spider species revealed by previous genomic study. In this work, a defensin-like antimicrobial peptide named Oh-defensin was purified and characterized from the venoms of the spider, Ornithoctonus hainana. Oh-defensin is composed of 52 amino acid (aa) residues including six Cys residues that possibly form three disulfide bridges. Its aa sequence is MLCKLSMFGAVLGV PACAIDCLPMGKTGGSCEGGVCGCRKLTFKILWDKKFG. By BLAST search, Oh-defensin showed significant sequence similarity to other arthropod antimicrobial peptides of the defensin family. Oh-defensin exerted potent antimicrobial activities against tested microorganisms including Gram-positive bacteria, Gram-negative bacteria, and fungi. The cDNA encoding Oh-defensin precursor was also cloned from the cDNA library of O. hainana.
3. Novel family of antimicrobial peptides from the skin of Rana shuchinae
Ruiqiang Zheng, Bin Yao, Haining Yu, Hanjin Wang, Jianmin Bian, Feifei Feng Peptides. 2010 Sep;31(9):1674-7. doi: 10.1016/j.peptides.2010.05.014. Epub 2010 May 27.
So far numerous antimicrobial peptides have been characterized from amphibians. In this work, a new family of antimicrobial peptides, named shuchin, was purified and characterized from skin secretions of the frog, Rana shuchinae that lives in freezing mountains. Totally two members of shuchin (shuchin 1 and 2) were identified with the amino acid sequence of NALSMPRNKCNRALMCFG and NALSSPRNKCDRASSCFG, respectively. cDNAs encoding shuchins were cloned from the skin cDNA library of R. shuchinae. The precursors of shuchin are composed of 62 amino acid residues including the conserved signal peptides, acidic propieces, and mature antimicrobial peptides. Synthetic shuchins showed strong and broad antimicrobial activities against Gram-positive bacteria (Staphylococcus aureus, and Bacillus cereus; MICs<12.5 microg/ml), Gram-negative bacteria (Escherichia coli, Bacillus dysenteriae, Pseudomonas aeruginosa; most MICs from 3.1 to 12.5 microg/ml), and yeast (Candida albicans; MICs of 6.25 microg/ml), but no hemolytic activity under the effective concentration, thereby provide more leading templates for designing novel anti-infection agents.
