Evidence for a novel biological role for the multifunctional β-1,3-glucan binding protein in shrimp.

β-1,3-Glucan binding proteins (βGBPs) are soluble pattern recognition proteins/receptors that bind to β-1,3-glucans from fungi cell walls. In crustaceans, βGBPs are abundant plasmatic proteins produced by the hepatopancreas, and have been proved to play multiple biological functions. Here, we purified and characterized novel members of the βGBP family from the hemolymph of two Brazilian shrimps, Farfantepenaeus paulensis (FpβGBP) and Litopenaeus schmitti (LsβGBP). As observed for other crustacean species, FpβGBP and LsβGBP are monomeric proteins (∼100kDa) able to enhance the activation of the prophenoloxidase system, a potent antimicrobial defense conserved in arthropods. More interestingly, we provided here evidence for a novel biological activity for shrimp βGBPs: the agglutination of fungal cells. Finally, we investigated the modulation of the βGBP gene in F. paulensis shrimps experimentally infected with a cognate fungal pathogen, Fusarium solani. From our expression data, βGBP gene is constitutively expressed in hepatopancreas and not modulated upon a non-lethal fungal infection. Herein, we have improved our knowledge about the βGBP family by the characterization of a novel biological role for this multifunctional protein in shrimp.