Purification, molecular cloning, and application of a novel sphingomyelin-binding protein (clamlysin) from the brackishwater clam, Corbicula japonica

Taketoshi Takara, Tetsuto Nakagawa, Masami Isobe, Nozomu Okino, Sachiyo Ichinose, Akira Omori, Makoto Ito

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Abstract

A novel sphingomyelin-binding protein (clamlysin) was purified from the foot muscle of a brackishwater clam, Corbicula japonica. The purified 24.8-kDa protein lysed sheep, horse and rabbit erythrocytes and the hemolytic activity was inhibited by sphingomyelin, but not other phospholipids or glycosphingolipids. The open reading frame of the clamlysin gene encoded a putative 26.9-kDa protein (clamlysin B) which showed high sequence similarity with the actinoporin family. A surface plasmon resonance assay confirmed that clamlysin B specifically bound to sphingomyelin. Furthermore, two cDNA variants of clamlysin, encoding putative 31.4 kDa (clamlysin A) and 11 kDa (clamlysin C) proteins, were isolated. Only the 31.4-kDa variant was found to exhibit sphingomyelin-binding activity. Clamlysin A and B, but not C, shared a sequence (domain II) conserved in all known sphingomyelin-binding proteins. Domain II fused with a glutathione S-transferase bound to sphingomyelin. Horse erythrocytes, mouse melanoma B16 and GM95 cells, and Chinese hamster ovary CHO-K1 cells, but not the same cells treated with bacterial sphingomyelinase, were immunostained with clamlysin B. These results indicate that clamlysin B binds to the sphingomyelin of living cells and thus would be useful as a molecular probe to detect sphingomyelin.

Original languageEnglish
Pages (from-to)323-332
Number of pages10
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume1811
Issue number5
DOIs
Publication statusPublished - May 1 2011

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All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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