“New insights into the functional analysis of a Fatty Acid Binding Protein from Echinococcus granulosus (EgFABP1)”

JORGE LUIS PÓRFIDO; VALERIA SILVA; GISELA FRANCHINI; ADRIANA ESTEVES; BETINA CÓRSICO

Salta

Encuentro; XXXIX Annual Meeting of the Argentinean Biophysical Society 2010/Workshop CeBEM-Structural Biology in Latin America/3rd Latin American Protein Society Meeting; 2010

Fatty Acid Binding Proteins (FABPs) are small cytosolic proteins (14-15 kDa) that are widely distributed in nature. In spite of the great amount of structural information available, their specific functions have not been established yet. Two members of this family (EgFABP1 and EgFABP2) have been identified in Echinococcus granulosus. Helminth parasites have a restricted lipid metabolism and must acquire lipids from the host. With the aim to contribute to the understanding of the specific role of these proteins in E. granulosus biology, we have analyzed EgFABP1´s ability to interact with ligands and membranes. Binding properties were explored employing fluorescently labelled fatty acids, as well as by analyzing the natural ligands bound to the recombinant protein. Although the protein binds the fluorescent analogues of 16:0 and 18:0 with submicromolar affinity, GLC analysis revealed that it is also able to bind other fatty acids from E. coli. Limited proteolysis experiments of the apo- and holo-forms of EgFABP1 clearly show that binding of the fatty acid consolidates the structure of the protein and prevents it from being further degraded by the protease. Protein-membrane interaction analysis was performed employing a cytochrome c competitive assay and the results suggest that EgFABP1 is able to interact with membranes. Further analyses are being undertaken in order to evaluate the factors that modulate such interactions. Understanding EgFABPs’ binding properties and their interactions with membranes could contribute to determine their functions and, more importantly, to the development of therapeutic strategies to control hydatid disease. Acknowledgments: We would like to thank Dra. Ana Ves Losada, Lic. Juan Pablo Layerenza and Martin Sisti for having kindly helped us with lipid analysis.