Characterization and functional analysis of fatty acid binding protein from the carcinogenic liver fluke, Opisthorchis viverrini

•Co-evolutionary of OvFABP and hL-FABP has been estimated.•Conserve of structure and function of OvFABP with other FABPs has been estimated.•Localization of OvFABP in vital organs of O. viverrini has been found.•The expression of OvFABP has been found throughout life cycle of O. viverrini.•Specific binding in in vitro of OvFABP with fatty acids has been found.

In the present study, the cDNA encoding FABP (Ov-FABP) was isolated from the adult stage of Opisthorchis viverrini and characterized. The Ov-FABP protein sequence (107 amino acids) was predicted to have a molecular mass of 12.26 kDa and an isoelectric point (PI) of 6.82. This sequence had a high identity and similarity to Cs-FABP of the related opisthorchid Clonorchis sinensis. Multiple sequence alignment with FABPs from other parasitic flatworms and mammals showed a number of conserved amino acids including Phe34, Gly37, Glu38, Glu39,Val50, Iso62, Gly81, Ile84, Ser87 and Arg101. In addition, the structure of Ov-FABP was predicted to have eleven β-sheets and one α-helix based on the known structures for FABPs from human (hL-FABP), rat and a schistosome. Phylogenetic analysis of amino acid sequence data revealed a close relationship of Ov-FABP with Cs-FABP and hL-FABP. Reverse transcription-PCR revealed that Ov-FABP was transcribed in the egg, metacercaria, juvenile and adult stages. The soluble form of recombinant Ov-FABP (rOv-FABP) was shown to specifically bind fatty acids, including oleic acid, palmitic acid and linoleic acid, as shown for other animals. Anti-serum against rOv-FABP (produced in mice) located the protein to parenchyma, egg, sucker musculature, testes and tegument of adult O. viverrini. Taken together, the findings suggest key functional roles for Ov-FABP in development, reproduction and/or host-parasite interactions.

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