title: Molecular characterization of an α-N-acetylgalactosaminidase from Clonorchis sinensis.
abstract: The α-N-acetylgalactosaminidase (α-NAGAL) is an exoglycosidase that selectively cleaves terminal α-linked N-acetylgalactosamines from a variety of sugar chains. A complementary DNA (cDNA) clone encoding a novel Clonorchis sinensis α-NAGAL (Cs-α-NAGAL) was identified in the expressed sequence tags database of the adult C. sinensis liver fluke. The complete coding sequence was 1,308 bp long and encoded a 436-residue protein. The selected glycosidase was manually curated as α-NAGAL (EC 3.2.1.49) based on a composite bioinformatics analysis including a search for orthologues, comparative structure modeling, and the generation of a phylogenetic tree. One orthologue of Cs-α-NAGAL was the Rattus norvegicus α-NAGAL (accession number: NP_001012120) that does not exist in C. sinensis. Cs-α-NAGAL belongs to the GH27 family and the GH-D clan. A phylogenetic analysis revealed that the GH27 family of Cs-α-NAGAL was distinct from GH31 and GH36 within the GH-D clan. The putative 3D structure of Cs-α-NAGAL was built using SWISS-MODEL with a Gallus gallus α-NAGAL template (PDB code 1ktb chain A); this model demonstrated the superimposition of a TIM barrel fold (α/β) structure and substrate binding pocket. Cs-α-NAGAL transcripts were detected in the adult worm and egg cDNA libraries of C. sinensis but not in the metacercaria. Recombinant Cs-α-NAGAL (rCs-α-NAGAL) was expressed in Escherichia coli, and the purified rCs-α-NAGAL was recognized specifically by the C. sinensis-infected human sera. This is the first report of an α-NAGAL protein in the Trematode class, suggesting that it is a potential diagnostic or vaccine candidate with strong antigenicity.
authors.affiliation: Division of Malaria and Parasitic Diseases, Korea National Institute of Health, Osong, Republic of Korea. blackcg96@gmail.com
authors.forename: Myoung-Ro
authors.initials: MR
authors.lastname: Lee
authors.forename: Won Gi
authors.initials: WG
authors.lastname: Yoo
authors.forename: Yu-Jung
authors.initials: YJ
authors.lastname: Kim
authors.forename: Dae-Won
authors.initials: DW
authors.lastname: Kim
authors.forename: Shin-Hyeong
authors.initials: SH
authors.lastname: Cho
authors.forename: Kwang Yeon
authors.initials: KY
authors.lastname: Hwang
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Ju
authors.forename: Won-Ja
authors.initials: WJ
authors.lastname: Lee
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D000947:Antigens, Helminth / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D003001:Cloning, Molecular; D003003:Clonorchiasis / Q000276:immunology; D003004:Clonorchis sinensis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D016000:Cluster Analysis; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D006801:Humans; D008958:Models, Molecular; D010802:Phylogeny; D011487:Protein Conformation; D017422:Sequence Analysis, DNA; D048809:alpha-N-Acetylgalactosaminidase / Q000737:chemistry / Q000235:genetics* / Q000276:immunology
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D048809:alpha-N-Acetylgalactosaminidase