Interaction of the hemolytic lectin CEL-III from the marine invertebrate Cucumaria echinata with the erythrocyte membrane.
CEL-III is one of four Ca(2+)-dependent galactose/N-acetylgalactosamine (GalNAc)-binding lectins from the marine invertebrate Cucumaria echinata which exhibits hemolytic activity, especially toward rabbit and human erythrocytes. The hemolytic activity of CEL-III was also Ca(2+)-dependent and was found to be inhibited by galactose or GalNAc-containing carbohydrates, suggesting that the hemolysis was caused by CEL-III binding to specific carbohydrates on the erythrocyte membrane by Ca(2+)-dependent lectin activity, followed by partial destruction of the membrane. The activity of CEL-III was highest at 10 degrees C and decreased markedly with increasing temperature, unlike usual enzymatic reactions. The hemolytic activity of CEL-III increased with increasing pH from neutral to 10, but almost no hemolysis was observed below pH 6.5. Immunoblotting analysis of proteins from the erythrocyte membrane after treatment with CEL-III indicated that CEL-III aggregates were irreversibly bound to the membrane. When erythrocytes were incubated with CEL-III in the presence of dextran with molecular masses greater than 4 kDa, lysis was impeded considerably, while a concomitant release of ATP was detected from these osmotically protected cells. It was found that CEL-III released carboxyfluorescein from artificial globoside-containing lipid vesicles, and it is suggested that CEL-III is a novel pore-forming protein with the characteristics of a Ca(2+)-dependent lectin, which may act as a toxic protein to foreign microorganisms.
Hatakeyama
T
T
Laboratory of Biochemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Nagatomo
H
H
Yamasaki
N
N
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002241:Carbohydrates / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D037102:Lectins / Q000378:metabolism*; D008081:Liposomes; D011817:Rabbits; D012616:Sea Cucumbers / Q000737:chemistry*; D013696:Temperature
D002241:Carbohydrates; D037102:Lectins; D008081:Liposomes; D000255:Adenosine Triphosphate