Purification and characterisation of a calcium-independent lectin (PjLec) from the haemolymph of the shrimp Penaeus japonicus

• DOI: 10.1016/j.fsi.2006.03.015
• Publication Date: 2006-07-08T11:20:27Z
• Authors: H YANG; T LUO; F LI; S LI; X XU
• Keywords: Male; 0301 basic medicine; Erythrocytes; Bacteria; Temperature; Hydrogen-Ion Concentration; Chromatography, Agarose; Molecular Weight; 03 medical and health sciences; Penaeidae; Agglutination Tests; Hemolymph; Lectins; Animals; Calcium; Female; alpha-Fetoproteins

A natural lectin (nominated PjLec) was isolated from haemolymph of the shrimp Penaeus japonicus by affinity chromatography with fetuin-Sepharose. The result of SDS-PAGE showed that the purified PjLec protein consisted of 37kDa subunits. The native PjLec behaved as a 452kDa protein in gel filtration chromatography. Those data suggest that PjLec is composed of 12 subunits of similar molecular weight. PjLec has a broad spectrum of bacterial-agglutination activities against both Gram-positive and Gram-negative bacteria, including two Vibrio species and two other strains pathogenic for shrimp. In addition, PjLec could agglutinate all the vertebrate erythrocytes tested, and the haemagglutination was calcium-independent. The haemagglutination of PjLec was inhibited by ManNAc, Neu5A and lipopolysaccharide. Bovine submaxillary mucin, which contains mainly Neu5A, was the most potent inhibitor of PjLec (MIC of 0.0006mgml(-1)). The haemagglutination activity of PjLec was stable between pH 6 and pH 8, and was temperature-dependent. Our results suggested that PjLec may be an important humoral defence factor against bacterial infection in P. japonicus.