The solution structure of horseshoe crab antimicrobial peptide tachystatin B with an inhibitory cystine-knot motif

Naoki Fujitani, Takahide Kouno, Taku Nakahara, Kenji Takaya, Tsukasa Osaki, Shun Ichiro Kawabata, Mineyuki Mizuguchi, Tomoyasu Aizawa, Makoto Demura, Shin Ichiro Nishimura, Keiichi Kawano

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23 Citations (Scopus)


Tachystatin B is an antimicrobial and a chitin-binding peptide isolated from the Japanese horseshoe crab (Tachypleus tridentatus) consisting of two isopeptides called tachystatin BI and B2. We have determined their solution structures using NMR experiments and distance geometry calculations. The 20 best converged structures of tachystatin B1 and B2 exhibited root mean square deviations of 0.46 and 0.49 Å, respectively, for the backbone atoms in Cys4-Arg4O. Both structures have identical conformations, and they contain a short antiparallel β-sheet with an inhibitory cystine-knot (ICI) motif that is distributed widely in the antagonists for voltage-gated ion channels, although tachystatin B does not have neurotoxic activity. The structural homology search provided several peptides with structures similar to that of tachystatin B. However, most of them have the advanced functions such as insecticidal activity, suggesting that tachystatin B may be a kind of ancestor of antimicrobial peptide in the molecular evolutionary history. Tachystatin B also displays a significant structural similarity to tachystatin A, which is member of the tachystatin family. The structural comparison of both tachystatins indicated that Tyr14 and Arg17 in the long loop between the first and second strands might be the essential residues for binding to chitin.

Original languageEnglish
Pages (from-to)269-279
Number of pages11
JournalJournal of Peptide Science
Issue number4
Publication statusPublished - Apr 2007

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmacology
  • Drug Discovery
  • Organic Chemistry


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