Binding of diarrheic shellfish poisoning toxins to okadaic acid binding proteins purified from the sponge Halichondria okadai

Keiichi Konoki, Kaori Saito, Hiroki Matsuura, Naoyuki Sugiyama, Yuko Cho, Mari Yotsu-Yamashita, Kazuo Tachibana

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Okadaic acid (OA) and dinophysistoxin-1 (DTX1) cause diarrheic shellfish poisoning. This article examines the biochemical interactions of the two toxins with novel okadaic acid binding proteins (OABPs) 2.1 and 2.3, originally isolated from the marine sponge Halichondria okadai. First, recombinant OABPs 2.1 and 2.3 were expressed in Escherichia coli BL21 (DE3) cells. Binding assays using [24-3H]OA and the recombinant OABP 2.1 or 2.3 demonstrated the dissociation constant Kd of 1.30 ± 0.56 nM and 1.54 ± 0.35 nM, respectively. Binding of [24-3H]okadaic acid to recombinant OABP2.1 was almost equally replaced with OA and DTX1. OA-induced cytotoxicity in mouse leukemia P388 cells was inhibited in the presence of the recombinant OABPs 2.1 and 2.3 with an EC50 of 92 ± 8.4 nM and 87 ± 13 nM, respectively. These results suggest that the blockage of OA-induced cytotoxicity by OABPs 2.1 and 2.3 may be involved in regulating symbiotic relationships present in the sponge H. okadai.

Original languageEnglish
Pages (from-to)7607-7610
Number of pages4
JournalBioorganic and Medicinal Chemistry
Volume18
Issue number21
DOIs
Publication statusPublished - 2010 Nov 1

Keywords

  • Binding
  • Cytotoxicity
  • Okadaic acid
  • Okadaic acid binding protein

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmaceutical Science
  • Drug Discovery
  • Clinical Biochemistry
  • Organic Chemistry

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