title: Molecular and biochemical characterization of Paragonimus westermani tyrosinase.
abstract: Trematode tyrosinases (TYRs) play a major role in the tanning process during eggshell formation. We investigated the molecular and biochemical features of Paragonimus westermani TYR (PwTYR). The PwTYR cDNA was composed of 1568-bp encompassing a 1422-bp-long open reading frame (474-amino acid polypeptide). A strong phylogenetic relationship with Platyhelminthes and Deuterostomian orthologues was evident. The recombinant PwTYR expressed in prokaryotic cells promptly oxidized diphenol substrates, with a preferential affinity toward ortho-positioned hydroxyl groups. It demonstrated fairly weak activity for monophenol compounds. Diphenol oxidase activity was augmented with an increase of pH from 5.0 to 8.0, while monophenol oxidase activity was highest at an acidic pH and gradually decreased as pH increased. Transcription profile of PwTYR was temporally upregulated along with worm development. PwTYR was specifically localized in vitellocytes and eggs. The results suggested that conversion of tyrosine to L-dihydroxyphenylalanine by PwTYR monophenol oxidase activity might be rate-limiting step during the sclerotization process of P. westermani eggs. The pH-dependent pattern of monophenol and diphenol oxidase activity further proposes that the initial hydroxylation might slowly but steadily progress in acidic secreted vesicles of vitellocytes and the second oxidation process might be rapidly accelerated by neural or weak alkaline pH environments within the ootype.
authors.affiliation: Department of Microbiology,Gachon University Graduate School of Medicine,Incheon 406-799,Korea.
authors.forename: Y-A
authors.initials: YA
authors.lastname: Bae
authors.affiliation: Department of Microbiology,Gachon University Graduate School of Medicine,Incheon 406-799,Korea.
authors.forename: S-H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Molecular Parasitology,Sungkyunkwan University School of Medicine, andCenter for Molecular Medicine,Samsung Biomedical Research Institute,Suwon 440-746,Korea.
authors.forename: C-S
authors.initials: CS
authors.lastname: Ahn
authors.affiliation: Department of Molecular Parasitology,Sungkyunkwan University School of Medicine, andCenter for Molecular Medicine,Samsung Biomedical Research Institute,Suwon 440-746,Korea.
authors.forename: J-G
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Molecular Parasitology,Sungkyunkwan University School of Medicine, andCenter for Molecular Medicine,Samsung Biomedical Research Institute,Suwon 440-746,Korea.
authors.forename: Y
authors.initials: Y
authors.lastname: Kong
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004528:Egg Shell / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism*; D010238:Paragonimus / Q000201:enzymology*; D011994:Recombinant Proteins; D014817:Vitelline Membrane / Q000201:enzymology
chemical_list: D018076:DNA, Complementary; D011994:Recombinant Proteins; D014442:Monophenol Monooxygenase
keywords: vitellocyte