THREE-DIMENSIONAL STRUCTURE AND LIGAND BINDING CAPACITY OF NA-FAR-1, THE NECATOR AMERICANUS FATTY ACID AND RETINOL BINDING PROTEIN

REY BURUSCO F; IBAÑEZ SHIMABUKURO M; COOPER A; KENNEDY MW; SMITH BO; B. CÓRSICO

La Plata

Congreso; 8ICLBP; 2013

ICLBPS

Necator americanus is the most prevalent hookworm species in the north of Argentina that causes anaemia and growth stunt especially in children [1]. Among the genes expressed by N. americanus, a fatty acid and retinol (FAR) protein, Na-FAR-1, has been identified [2]. FARs are a novel class of α helix-rich fatty acid and retinol binding proteins of around 20 kDa molecular weight [3] which are exclusive to nematodes and are secreted by the parasites into the surrounding tissues of the host. FARs may play a role in the establishment of the infection thus making them candidate targets for drug or vaccine development. The three-dimensional structure of Na-FAR-1 was solved in solution by NMR spectroscopy. Protein folding reveals the presence of eleven alpha-helices that define an internal hydrophobic cavity. The overall fold is similar to that obtained for the holo crystal structure [4], but the size of the cavity changes dramatically. NMR titration experiments reveal the presence of three high affinity binding sites and an additional low affinity binding site, suggesting a final 1 to 4 protein to ligand stoichiometry. Examination of the lipid composition of the ligands bound to the purified recombinant protein shows the presence of phospholipids, indicating that Na-FAR-1 ligand binding preferences are not limited to fatty acids and retinol. The results of the present work constitute the first structural characterization of a parasite FAR protein and a new step in the understanding of its biological function. [1] Menghi CI, Iuvaro FR, Dellacasa MA, Gatta CL (2007). Medicina (BsAs). 67(6 Pt 2):705-8. [2] Daub J, Loukas A, Pritchard DI, Blaxter M (2000). Parasitology 120 ( Pt 2):171-184 [3] Kennedy MW, Garside LH, Goodrick LE, McDermott L, Brass A, Price NC, Kelly SM, Cooper A, Bradley JE (1997). J Biol Chem 272 (47):29442-29448. [4] Gabrielsen M, Rey-Burusco MF, Griffiths K, Roe AJ, Cooper A, Smith BO et al. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68(Pt 7):83