Purification, characterization and cDNA cloning of a novel lectin from the jellyfish Nemopilema nomurai

A lectin (designated NnL) from a jellyfish Nemopilema nomurai was purified by ion-exchange chromatography followed by affinity chromatography. The apparent molecular mass of NnL was 28 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. NnL agglutinated horse erythrocytes, the gram-positive bacterium Bacillus subtilis and gram-negative bacterium Escherichia coli K12. The hemagglutinating activity of NnL was inhibited by N-acetyl-D-galactosamine N-acetylneuraminic acid and N-glycolylneuraminic acid. Bovine submaxillary mucin was the potent inhibitor of the hemagglutinating activity of NnL among the glycoproteins tested. cDNA cloning of NnL revealed that its primary structure contained part of a fibrinogen-like domain. The deduced amino acid sequence of NnL showed no significant sequence identities to other known lectins. On the other hand NnL showed high sequence identity to a predicted protein of the sea anemone Nematostella vectensis suggesting that NnL may belong to a novel lectin family in metazoans. This is the first report to describe the purification characterization and cDNA cloning of a jellyfish lectin.