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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