title: Diversity in the structures and ligand-binding sites of nematode fatty acid and retinol-binding proteins revealed by Na-FAR-1 from Necator americanus.
abstract: Fatty acid and retinol-binding proteins (FARs) comprise a family of unusual α-helix rich lipid-binding proteins found exclusively in nematodes. They are secreted into host tissues by parasites of plants, animals and humans. The structure of a FAR protein from the free-living nematode Caenorhabditis elegans is available, but this protein [C. elegans FAR-7 (Ce-FAR-7)] is from a subfamily of FARs that does not appear to be important at the host/parasite interface. We have therefore examined [Necator americanus FAR-1 (Na-FAR-1)] from the blood-feeding intestinal parasite of humans, N. americanus. The 3D structure of Na-FAR-1 in its ligand-free and ligand-bound forms, determined by NMR (nuclear magnetic resonance) spectroscopy and X-ray crystallography respectively, reveals an α-helical fold similar to Ce-FAR-7, but Na-FAR-1 possesses a larger and more complex internal ligand-binding cavity and an additional C-terminal α-helix. Titration of apo-Na-FAR-1 with oleic acid, analysed by NMR chemical shift perturbation, reveals that at least four distinct protein-ligand complexes can be formed. Na-FAR-1 and possibly other FARs may have a wider repertoire for hydrophobic ligand binding, as confirmed in the present study by our finding that a range of neutral and polar lipids co-purify with the bacterially expressed recombinant protein. Finally, we show by immunohistochemistry that Na-FAR-1 is present in adult worms with a tissue distribution indicative of possible roles in nutrient acquisition by the parasite and in reproduction in the male.
authors: Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, calles 60 y 120, 1900-La Plata, Argentina.
authors: M Florencia
authors: MF
authors: Rey-Burusco
authors: Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, calles 60 y 120, 1900-La Plata, Argentina.
authors: Marina
authors: M
authors: Ibáñez-Shimabukuro
authors: Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8QQ, U.K.
authors: Mads
authors: M
authors: Gabrielsen
authors: Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, calles 60 y 120, 1900-La Plata, Argentina.
authors: Gisela R
authors: GR
authors: Franchini
authors: Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8QQ, U.K.
authors: Andrew J
authors: AJ
authors: Roe
authors: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, U.K.
authors: Kate
authors: K
authors: Griffiths
authors: National School of Tropical Medicine and Department of Pediatrics, Section of Tropical Medicine, Baylor College of Medicine, Houston, TX 20031, U.S.A.
authors: Bin
authors: B
authors: Zhan
authors: School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
authors: Alan
authors: A
authors: Cooper
authors: Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, U.K. Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, U.K. Brian.Smith@glasgow.ac.uk malcolm.kennedy@glasgow.ac.uk.
authors: Malcolm W
authors: MW
authors: Kennedy
authors: Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, calles 60 y 120, 1900-La Plata, Argentina.
authors: Betina
authors: B
authors: Córsico
authors: Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, U.K. Brian.Smith@glasgow.ac.uk malcolm.kennedy@glasgow.ac.uk.
authors: Brian O
authors: BO
authors: Smith
mesh_terms: D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000378:metabolism / Q000472:pathogenicity; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism; D006790:Host-Parasite Interactions; D008024:Ligands; D017221:Necator americanus / Q000737:chemistry / Q000378:metabolism* / Q000472:pathogenicity; D009332:Necatoriasis / Q000378:metabolism* / Q000469:parasitology; D012098:Reproduction; D012177:Retinol-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; C473216:FAR protein, C elegans; D005227:Fatty Acids; D008024:Ligands; D012177:Retinol-Binding Proteins
keywords: Necator americanus; X-ray; fatty acid-binding protein; nematode; nuclear magnetic resonance (NMR); parasite; protein structure; retinol-binding protein