Size-dependent haemagglutinating activity in the haemolymph from sub-adult blue shrimp (Penaeus stylirostris stimpson)

Multifunctional role of β-1, 3 glucan binding protein purified from the haemocytes of blue swimmer crab Portunus pelagicus and in vitro antibacterial activity of its reaction product

β-1, 3 glucan binding protein (β-GBP) was isolated from the haemocytes of blue swimmer crab, Portunus pelagicus and purified by laminarin coupled Sephadex G-100 affinity column chromatography. The purified β-GBP has the molecular mass of 100 kDa, confirmed by SDS-PAGE. The X-ray diffraction analysis of purified β-GBP indicates the crystalline nature of the protein and also the presence of single peak confirming the existence of β-glucan molecule. The results of agglutination assay showed that the purified β-GBP had the ability to agglutinate with yeast cell, Saccharomyces cerevisiae and mammalian erythrocytes. β-GBP can agglutinate with yeast cells at the concentration of 50 μg/ml. The phagocytic and encapsulation activity of purified β-GBP from P. pelagicus was determined with yeast cell S. cerevisiae and sepharose bead suspension respectively. This reveals that, β-GBP have the ability to detect the pathogen associated molecular patterns (PAMP) found on the surface of fungi and bacteria. The recognition of invading foreign substances and in the involvement of functional activities induces the activation of prophenoloxidase. This revealed that β-GBP play a major role in the innate immune system of crustaceans by stimulating the prophenoloxidase system. Moreover, it was obvious to note that β-GBP reaction product exhibited antibacterial and antibiofilm activity against Gram positive and Gram negative bacteria. This study concludes the functional aspects of β-GBP purified from P. pelagicus and its vital role in the stimulation of prophenoloxidase cascade during the pathogenic infection.

Purification, characterization and functional analysis of a novel β-1, 3-glucan binding protein from green tiger shrimp Penaeus semisulcatus

A β-1, 3-Glucan binding protein (β-GBP) was isolated from green tiger shrimp Penaeus semisulcatus and purified using laminarin precipitation and affinity chromatography on laminarin-Sepharose 6B column respectively. P. semisulcatus β-GBP exhibits a single band with a molecular weight of 112 kDa on SDS-PAGE and pI of 5.9 in isoelectric focusing (IEF). Negative staining of P. semisulcatus β-GBP showed large aggregates with crystalline surface when viewed by Electron Microscopy. Circular dichroism spectra of P. semisulcatus β-GBP showed broad negative minimum wavelength extending from 200 to 250 nm can be attributed to the presence of β-sheets in its secondary structure. P. semisulcatus β-GBP comprises the specific binding affinity with the polysaccharide β-1, 3-glucans (laminarin), this recognition and binding leads to the activation of prophenoloxidase cascade. Interestingly, P. semisulcatus β-GBP also involved in the agglutination of baker's yeast, bacteria, erythrocytes (RBCs) and enhances the PO activity. Herein, we have investigated the importance of β-GBP in innate immune response of P. semisulcatus and they implicate the evolutionary link with similar proteins found in other invertebrates.

A heterogeneous sialic acid-binding lectin with affinity for bacterial LPS from horse mussel (Modiolus modiolus) hemolymph

A sialic acid-binding lectin that agglutinates a variety of erythrocytes and bacteria and react with sialoconjugates and purified lipopolysaccharides from marine vibrios has been affinity purified from hemolymph of the horse mussel Modiolus modiolus using Bovine submaxillary mucin conjugated to CNBr-activated Sepharose 4B. The lectin demonstrated heterogeneous activity, and at least two main entities were partially characterized, and are referred to as modiolin H and modiolin E activities for the agglutination of human and horse (equine) erythrocytes, respectively. Only modiolin E activity required calcium ions for hemagglutination. The M. modiolus lectin was mainly specific for NeuAc, although the lectin demonstrated a broader range of specificity, similarly to the Limulus polyphemus lectin. The purified lectin was a glycoprotein, and in the native state existed as aggregates with M(r) in the range of 100-1,300 kDa as observed by gradient-gel electrophoresis and gel filtration on Biogel and Superose. SDS-PAGE under reducing conditions revealed three subunits of M(r) 14, 17.5 and 20 kDa. Various marine bacteria adsorbed the hemagglutinating activities of the M. modiolus lectin. Purified LPS preparations from various pathogenic marine vibrios were also effective inhibitors, in particular for modiolin E activity. These results indicate that the lectin play a role in recognition of bacteria.

Purification and comparison of beta-1,3-glucan binding protein from white shrimp (Penaeus vannamei)

A beta-glucan binding protein (BGBP) was identified in both white (Penaeus vannamei) and blue shrimp (P. stylirostris) plasma. White shrimp BGBP was purified by affinity chromatography using immobilized laminarin, and its molecular and biological properties were described. White shrimp BGBP is a monomeric protein with a molecular mass of 100 kDa, similar to those described for other crustacean BGBPs. White and blue shrimp BGBPs can be detected with antisera against crayfish BGBP and brown shrimp BGBP. Both amino acid composition and N-terminal sequence are markedly similar to brown shrimp (P. californiensis) and crayfish (Pacifastacus leniusculus) BGBP, indicating that this recognition protein is present in freshwater and marine crustaceans.