FhCaBP4: A Fasciola hepatica calcium-binding protein with EF-hand and dynein light chain domains

Rebecca Orr, Ruth Kinkead, Richard Newman, Lindsay Anderson, Elizabeth M. Hoey, Alan Trudgett, David J. Timson

    Research output: Contribution to journalArticlepeer-review


    In trematodes, there is a family of proteins which combine EF-hand-containing domains with dynein light chain (DLC)-like domains. A member of this family from the liver fluke, Fasciola hepatica - FhCaBP4 - has been identified and characterised biochemically. FhCaBP4 has an N-terminal domain containing two imperfect EF-hand sequences and a C-terminal dynein light chain-like domain. Molecular modelling predicted that the two domains are joined by a flexible linker. Native gel electrophoresis demonstrated that FhCaBP4 binds to calcium, manganese, barium and strontium ions, but not to magnesium or zinc ions. The hydrophobic, fluorescent probe 8-anilinonaphthalene-1-sulphonate bound more tightly to FhCaBP4 in the presence of calcium ions. This suggests that the protein undergoes a conformational change on ion binding which increases the number of non-polar residues on the surface. FhCaBP4 was protected from limited proteolysis by the calmodulin antagonist W7, but not by trifluoperazine or praziquantel. Protein-protein cross-linking experiments showed that FhCaBP4 underwent calcium ion-dependent dimerisation. Since DLCs are commonly dimeric, it is likely that FhCaBP4 dimerises through this domain. The molecular model reveals that the calcium ion-binding site is located close to a key sequence in the DLC-like domain, suggesting a plausible mechanism for calcium-dependent dimerisation.

    Original languageEnglish
    Pages (from-to)1707-1713
    Number of pages7
    JournalParasitology Research
    Issue number4
    Publication statusPublished - 1 Oct 2012


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