ABA-1A: a Nematode Polyprotein Allergen (NPA) of Ascaris suum. Structure and binding properties.

GISELA R. FRANCHINI; JULIAN A. BELGAMO; MALCOLM W. KENNEDY; BRIAN O. SMITH; BETINA CÓRSICO

Sierra de la Ventana, Buenos Aires

Congreso; XLIII Reunión anual de la Sociedad Argentina de Biofísica; 2014

Sociedad Argentina de Biofísica

The acquisition and transport of lipids from their hosts is crucial to parasitic helminths, being the proteins and receptors involved in lipid transport and exchange potential targets for chemo- and immunotherapy. Among helminth lipid binding proteins (LBPs), the polyprotein allergens/antigens of nematodes (NPAs) represent a novel class of lipid binding proteins which has been described exclusively in nematodes. NPAs are small, helix-rich proteins, and have no known structural counterparts in other phyla. The biochemical activity of the NPA of A. suum was first described as a binding protein for small lipids such as fatty acids and retinoids. Recently, the structure of a single unit of the polyprotein array (ABA-1A) has been solved in the presence of saturating concentration of oleic acid describing two binding sites. In the present project we are working with ABA-1A in the absence of the ligand (apo- form) and its atomic structure is under analysis employing NMR spectroscopy, for which high quality data have already been obtained and full structure calculation is in progress. In order to obtain more information about the structural perturbations due to ligand binding; an oleic acid titration of ABA-1A monitored by NMR spectroscopy was performed. Briefly, it was possible to distinguish two binding events according to the nature of the perturbations observed. Additionally, as a first attempt to determine the natural ligands bound by this protein a lipidomic analysis was done using recombinant ABA-1A without the delipidation step.