1H, 13C and 15N chemical shift assignments of Na-FAR-1, a helix-rich fatty acid and retinol binding protein of the parasitic nematode Necator americanus

The fatty acid and retinol-binding (FAR) proteins are a family of unusual helix-rich lipid binding proteins found exclusively in nematodes, and are secreted by a range of parasites of humans, animals and plants. Na-FAR-1 is from the parasitic nematode Necator americanus, an intestinal blood-feeding parasite of humans. Sequence-specific H-1, C-13 and N-15 resonance assignments have been obtained for the recombinant 170 amino acid protein, using three-dimensional triple-resonance heteronuclear magnetic resonance experiments. Backbone assignments have been obtained for 99.3 % of the non-proline HN/N pairs (146 out of 147). The amide resonance of T45 was not observed, probably due to rapid exchange with solvent water. A total of 96.9 % of backbone resonances were identified, while 97.7 % assignment of amino acid sidechain protons is complete. All H alpha(166), H beta(250) and H gamma(160) and 98.4 % of the H delta (126 out of 128) atoms were assigned. In addition, 99.4 % C alpha (154 out of 155) and 99.3 % C beta (143 out of 144) resonances have been assigned. No resonances were observed for the NHn groups of R93 N epsilon H epsilon, arginine, N eta 1H2, N eta 2H2, histidine N delta 1H delta 1, N epsilon 1H epsilon 1 and lysine N zeta 3H3. Na-FAR-1 has a similar overall arrangement of alpha-helices to Ce-FAR-7 of the free-living Caeorhabditis elegans, but with an extra C-terminal helix.