Pattern Recognition Protein Binds to Lipopolysaccharide and β-1,3-Glucan and Activates Shrimp Prophenoloxidase System

Abstract

Background:LGBP is an important pattern recognition protein (PRP). Results: PmLGBP binds to ␤-1,3-glucan and LPS and could enhance the phenoloxidase (PO) activity. Knockdown shrimp showed decreased PO activity. Conclusion: PmLGBP functions as a PRP for LPS and ␤-1,3-glucan in the proPO system. Significance: PmLGBP is a PRP involved in the proPO system, exhibits LPS and ␤-1,3-glucan binding activity, and can activate the proPO system.

A glycosyl hydrolase family 16 gene is responsible for the endogenous production of β-1,3-glucanases within decapod crustaceans

“…LGBPs of 349-376 amino acids (approximately 36-41 kDa) with both catalytic and binding domains (Lee et al, 2000;Roux et al, 2002;Sritunyalucksana et al, 2002;Lin et al, 2008;Liu et al, 2009;Yeh et al, 2009;Zhao et al, 2009;Amparyup et al, 2012). The size discrepancy and presence of a catalytic domain in these proteins suggest that the more recently identified proteins are not, in fact, related to that described by Cerenius et al, 1994.…”

“…It is likely that the β-1,3-glucanase is the product of a glycosyl hydrolase family 16 (GHF16) gene given that this gene has been confirmed to produce a similar enzyme (of 30-50 kDa) in other invertebrates (Table 1). Interestingly, although a digestive β-1,3-glucanase gene has not yet been identified, crustaceans do possess a similar GHF16 gene that produces a lipopolysaccharide and β-1,3-glucan binding protein (LGBP) (Lee et al, 2000;Sritunyalucksana et al, 2002;Du et al, 2007;Lin et al, 2008;Amparyup et al, 2012). This protein is primarily expressed in the haemocytes and is believed to play an immune role.…”

“…This protein is primarily expressed in the haemocytes and is believed to play an immune role. Specifically, LGBPs bind lipopolysaccharides and β-1,3-glucans and this, via the prophenol oxidase system, stimulates an immune response (Lee et al, 2000;Sritunyalucksana and Söderhäll, 2000;Amparyup et al, 2012).…”

“…The crustacean GHF16 gene produces a protein with both a catalytic and a binding domain, as seen in β-1,3-glucanases (Lee et al, 2000;Amparyup et al, 2012) and thus is classed as a glycosyl hydrolase. It has been suggested that the catalytic domain is inactive and therefore the protein lacks activity; however, this conclusion is based on a different protein that was initially identified as LGBP.…”

Isolation of a novel LPS-induced component of the ML superfamily in Ciona intestinalis

“…In invertebrates, the mechanisms behind LPS recognition has been investigated in particular in crustaceans where the binding of a b-glucan-binding proteins (bGBPs) to LPS has been described leading to the activation of the proPO system of the freshwater crayfish, Pacifastacus leniusculus (Lee et al, 2000). In shrimp, several LPS b-1,3-glucan binding proteins (LGBPs) have been cloned and characterized (Amparyup et al, 2012;Cheng et al, 2005;Du et al, 2007;Roux et al, 2002) but very little is known in Ascidiacea.…”