FMRFamide-like neuropeptides as putative ligands of the latrophilin-like HC110-R from Haemonchus contortus.

The latrophilin-like receptor HC110-R of the parasitic nematode Haemonchus contortus has been previously identified as a target for the novel anthelmintic drug emodepside, but the natural ligand(s) remained completely unknown to date. Here, we investigate 11 different FMRFamide-like neuropeptides as putative ligands by surface plasmon resonance with an immobilized recombinant 54kDa aminoterminal fragment of HC110-R as an interaction partner. AF1, AF10 and PF2 exhibit binding with low affinities as indicated by a K(d) of 11 microM for AF1, 52 microM for AF10 and 583 microM for PF2. Our data indicate that AF1, AF10, and PF2 are putative natural ligands of HC110-R presumably involved in the control of pharyngeal pumping of nematode worms.