Identification and characterization of multiple β-glucan binding proteins in the Pacific oyster, Crassostrea gigas

• Published in: Developmental and comparative immunology 2010-04, Vol.34 (4), p.445-454
• Main Authors: Itoh, Naoki, Kamitaka, Ryo, Takahashi, Keisuke G., Osada, Makoto
• Format: Article
• Language: English
• Subjects: Animals; Carrier Proteins - genetics; Carrier Proteins - immunology; Carrier Proteins - metabolism; Cells, Cultured; Cloning, Molecular; Crassostrea - physiology; Crassostrea gigas; Digestive System - immunology; Digestive System - metabolism; Evolution, Molecular; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Enzymologic - immunology; Glucans; Hemocytes; Hemocytes - immunology; Hemocytes - metabolism; Innate immunity; Lectins - genetics; Lectins - immunology; Lectins - metabolism; Marine; Monophenol Monooxygenase - genetics; Monophenol Monooxygenase - immunology; Monophenol Monooxygenase - metabolism; Pacific oyster; Pattern recognition receptors (PRRs); Phenoloxidase; Polysaccharides - metabolism; Protein Structure, Tertiary - genetics; Recombinant protein; β-Glucan binding proteins
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2009.12.003

The present study reports on the characterization of two cDNAs coding β-glucan binding proteins (βGBPs), designated as Cg-βGBP-1 and Cg-βGBP-2, from the Pacific oyster, Crassostrea gigas. Cg-βGBP-1 consists of 555 amino acid residues and possesses two possible integrin recognition sites. The other protein, Cg-βGBP-2, is composed of 447 amino acid residues without integrin recognition sites. Domain structures of both Cg-βGBPs are similar to other invertebrate βGBPs, but phylogenetic positions and major expression tissues for these proteins are different. Cg-βGBP-1 is expressed in circulatory hemocytes and Cg-βGBP-2 in digestive glands. Functional assays using recombinant proteins revealed that Cg-βGBP-2 enhanced the phenoloxidase (PO) activity of hemocyte suspensions under the presence of laminarin, but Cg-βGBP-1 did not show this enhancement. It is suggested that Cg-βGBPs in the Pacific oyster have evolved to obtain different immunological functions. Cg-βGBP-1 possibly evolved for hemocyte-related functions through integrin, and Cg-βGBP-2 for the PO activation system.