title: Molecular characterization of Galectin-8 from Nile tilapia (Oreochromis niloticus Linn.) and its response to bacterial infection.
abstract: Galectins belong to the family of galactoside-binding proteins and play a major role in the immune and inflammatory responses of vertebrates and invertebrates. The galectin family is divided into three subtypes based on molecular structure; prototypes, chimera types, and tandem-repeated types. We isolated and characterized the cDNA of galectin-8 (OnGal-8) in Nile tilapia (Oreochromis niloticus). OnGal-8 consisted of a 966 bp open reading frame (ORF) that encoded a 321 amino acid protein (43.47 kDa). Homology and phylogenetic tree analysis suggested the protein was clustered with galectin-8s from other animal species and shared at least 56.8% identity with salmon galectin-8. Structurally, the amino acid sequence included two distinct N- and C- terminus carbohydrate recognition domains (CRDs) of 135 and 133 amino acids, respectively, that were connected by a 39 amino acid polypeptide linker. The N- and C-CRDs contained two conserved WG-E-I and WG-E-T motifs, suggesting they have an important role in mediating the specific interactions between OnGal-8 and saccharide moieties such as β-galactoside. The structure of OnGal-8 was characterized by a two-fold symmetric pattern of 10-and 12-stranded antiparallel ß-sheets of both N- and C-CRDs, and the peptide linker presumably formed a random coil similar to the characteristic tandem-repeat type galectin. The expression of OnGal-8 in healthy fish was highest in the skin, intestine, and brain. Experimental challenge of Nile tilapia with S. agalactiae resulted in significant up-regulation of OnGal-8in the spleen after 5 d. Our results suggest that OnGal-8 is involved in the immune response to bacterial infection.
authors.affiliation: Department of Biochemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan, Chatuchak, Bangkok 10900, Thailand; Biochemical Research Unit for Feed Utilization Assessment, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. Electronic address: fscissmn@ku.ac.th.
authors.forename: Sasimanas
authors.initials: S
authors.lastname: Unajak
authors.affiliation: Department of Biochemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Nutthida
authors.initials: N
authors.lastname: Pholmanee
authors.affiliation: Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Napat
authors.initials: N
authors.lastname: Songtawee
authors.affiliation: Laboratory of Animal Cytogenetics and Comparative Genomics, Department of Genetics, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Kornsorn
authors.initials: K
authors.lastname: Srikulnath
authors.affiliation: Department of Aquaculture, Faculty of Fisheries, Kasetsart University, 50 Ngam Wong Wan Road, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Prapansak
authors.initials: P
authors.lastname: Srisapoome
authors.affiliation: Department of Biochemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Asama
authors.initials: A
authors.lastname: Kiataramkul
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-Ku, Tokyo 108-8477, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Hirono
authors.affiliation: Department of Aquaculture, Faculty of Fisheries, Kasetsart University, 50 Ngam Wong Wan Road, Chatuchak, Bangkok 10900, Thailand.
authors.forename: Nontawith
authors.initials: N
authors.lastname: Areechon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D023681:Cichlids / Q000235:genetics / Q000276:immunology*; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology*; D037161:Galectins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D051192:Receptors, Pattern Recognition / Q000276:immunology; D016415:Sequence Alignment; D013290:Streptococcal Infections / Q000276:immunology / Q000662:veterinary*; D013292:Streptococcus agalactiae
chemical_list: D037161:Galectins; D051192:Receptors, Pattern Recognition
keywords: Galectin-8; Nile tilapia; Oreochromis niloticus; Streptococcus agalactiae