P-defensins

Howell MD The role of human p defensins and cathelicidins in atopic dermatitis. Curr Opin Allergy Clin Immunol 2007 7 413-417. 

Figure 31-7 Ribbon structures of some defensins. (A) Structure of a human fl-defensin showing the three disulfide bonds. From Bauer et al.134 Courtesy of Heinrich Sticht. (B) Comparison of the folding patterns of four types of defensins. Mammalian a- and P-defensins are all P sheets with somewhat different arrangements of disulfide bridges. Insect and plant defensins have an a helix joined to the P sheet. Mammalian and insect defensins have three disulfide bridges, while plant defensins have four. From Hoffmann et al.12 Courtesy of Jules A. Hoffmann.

A number of endogenous chemicals provide effective barriers in innate immunity. They include hydrolytic enzymes of saliva, low pH of stomach and vagina and proteolytic enzymes in the small intestine. Additional examples include cryp-tidins, a-defensins, (3-defensins, interferons (IFNs), and surfactant proteins A and D. Cryptidins and a-defensins are produced in the small intestine and p-defensins are produced by the skin and respiratory tract. 

VSL 3 probiotic mixture Improves epithelial barrier function Induces human p-defensin, hBD-2 gene expression Schlee et al. (2008)... 

Wehkamp, J., Harder, J., Wehkamp, K., Wehkamp-von Meissner, B., Schlee, M., Enders, C., Sonnenborn, U., Nuding, S., Bengmark, S., Fellermann, K., Schroder, J. M., and Stange, E. F. (2004). NF-kB- and AP-l-mediated induction of human p-defensin-2 in intestinal epithelial cells by Escherichia coli Nissle 1917 A novel effect of a probiotic bacterium. Infect. Immun. 72(10), 5750-5758. 

Goldman Ml, Stotzenberg ED, Karl UP, Zasloff M, Wilson JM Human p-defensin-1 is a salt-sensitive antibiotic in lung that is inactivated in cystic fibrosis. Cell 1997 88 553-560. 

A subset of defensins, the P-defensins, have been isolated from bovine neutrophils (10). A unique consensus sequence distinguishes these defensins from those described above, although both contain the characteristic three disulfide bridges. Tracheal antimicrobial peptide (TAP) isolated from the bovine respiratory tract also contains the triple disulfide motif but is specifically expressed in the lespiratory tract (II). This peptide is active against Cram-negative and -positive bacteria and yeast,... 

P defensins 3 disulfides P-srranded Bovine neutrophils, trachea TAP. BNBD... 

Tang, Y.Q. andM.E. Selsted, 1993. Characterization of the disulfide motifin in BNBD-12, an antimaicrobial p-defensin peptide from bovine neutrophil. J. Bio. Chem.268, 6649-6653. 

Defensins are small (3.5-4.5 kDa), cationic and amphipathic peptides with six conserved cysteine residues. They can be classified as a-, P- or 0-defensins depending on the position of the cysteines and topology of the disulphide bonds. Only P-defensin (BD) genes have been found so far in fish (Cuesta et al., 2011), first identified in zebrafish, tetraodon and fugu aided by their sequenced genomes (Zou et al., 2007). BD were later cloned in rainbow trout and other fish species (Casadei et al., 2009 Falco et al., 2008 Zhao et al., 2009 Jin et al., 2010 Nam et al., 2010 Cuesta et al., 2011). 

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