Horseshoe crab hemocyte-derived antimicrobial polypeptides, tachystatins, with sequence similarity to spider neurotoxins

Tsukasa Osaki, Miyuki Omotezako, Ranko Nagayama, Michimasa Hirata, Sadaaki Iwanaga, Jiro Kasahara, Junji Hattori, Isao Ito, Hiroyuki Sugiyama, Shun Ichiro Kawabata

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102 Citations (Scopus)


Antimicrobial peptides, named tachystatins A, B, and C, were identified from hemocytes of the horseshoe crab Tachypleus tridentatus. Tachystatins exhibited a broad spectrum of antimicrobial activity against Gram-negative and Gram-positive bacteria and fungi. Of these tachystatins, tachystatin C was most effective. Tachystatin A is homologous to tachystatin B, but tachystatin C has no significant sequence similarity to tachystatins A and B. Tachystatins A and B showed sequence similarity to ω-agatoxin-IVA of funnel web spider venom, a potent blocker of voltage-dependent calcium channels. However, they exhibited no blocking activity of the P-type calcium channel in rat Purkinje cells. Tachystatin C also showed sequence similarity to several insecticidal neurotoxins of spider venoms. Tachystatins A, B, and C bound significantly to chitin. A causal relationship was observed between chitin binding activity and antifungal activity. Tachystatins caused morphological changes against a budding yeast, and tachystatin C had a strong cell lysis activity. The septum between mother cell and bud, a chitin-rich region, was stained by fluorescence-labeled tachystatin C, suggesting that the primary recognizing substance on the cell wall is chitin. As horseshoe crab is a close relative of the spider, tachystatins and spider neurotoxins may have evolved from a common ancestral peptide, with adaptive functions.

Original languageEnglish
Pages (from-to)26172-26178
Number of pages7
JournalJournal of Biological Chemistry
Issue number37
Publication statusPublished - Sept 10 1999

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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