1cix: Difference between revisions

[[Image:1cix.gif|left|200px]]<br /><applet load="1cix" size="350" color="white" frame="true" align="right" spinBox="true"  

The solution structure of antimicrobial peptide tachystatin A from the Japanese horseshoe crab (Tachypleus tridentatus) was determined by two-dimensional nuclear magnetic resonance measurements and distance-restrained simulated annealing calculations. The correct pairs of disulfide bonds were also confirmed in this study. The obtained structure has a cysteine-stabilized triple-stranded beta-sheet as a dominant secondary structure and shows an amphiphilic folding observed in many membrane-interactive peptides. Interestingly, tachystatin A shares structural similarities with the calcium channel antagonist omega-agatoxin IVA isolated from spider toxin and mammalian defensins, and we predicted that omega-agatoxin IVA also have the antifungal activity. These structural comparisons and functional correspondences suggest that tachystatin A and omega-agatoxin IVA may exert the antimicrobial activity in a manner similar to defensins, and we have confirmed such activity using fungal culture assays. Furthermore, tachystatin A is a chitin-binding peptide, and omega-agatoxin IVA also showed chitin-binding activities in this study. Tachystatin A and omega-agatoxin IVA showed no structural homology with well known chitin-binding motifs, suggesting that their structures belong to a novel family of chitin-binding peptides. Comparison of their structures with those of cellulose-binding proteins indicated that Phe(9) of tachystatin A might be an essential residue for binding to chitin.

1CIX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Tachypleus_tridentatus Tachypleus tridentatus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CIX OCA].  

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