A novel beta-galactose-specific lectin of the tubeworm, Ridgeia piscesae , from the hydrothermal vent

Lectins are sugar-specific binding proteins or glycoproteins that play important physiological roles in cellular recognition and regulation. And they are also valuable in medicine and pharmacy. Tubeworm is the representative species around the hydrothermal vent in the deep sea. They have developed unique mechanisms to adapt to the harsh environment. In this study, a 1 092 bp cDNA, designed as rpgal , was first cloned and characterized from the tubeworm Ridgeia piscesae . Sequence analysis showed that RPGAL had low homology with the known galectin. And it had two homologous carbohydrate-recognition domains, which is the characteristic of the tandem-repeat type galectins. The RPGAL was successfully recombinant expressed in Escherichia coli and purified. Analysis of biological activity revealed that RPGAL was metal ion independent and it could agglutinate all the vertebrate erythrocytes tested. It was stable at 10–50°C and pH 5–10. And the hemagglutinating activity of RPGAL was strongly inhibited by D-Lactose and lipopolysaccharide. Although RPGAL had no effect on the microorganisms tested, it showed anti-tumor activity towards HeLa cells and HT1080 cells, which was accomplished by apoptosis. The study demonstrated that RPGAL was a novel galectin and provided a potential candidate for therapy of anti-tumor.