Direct interaction between EgFABP1, a fatty acid binding protein from Echinococcus granulosus, and membranes.

PÓRFIDO, JL; ALVITE, G; SILVA V; ESTEVES, A; CÓRSICO, B

PLOS NEGLECTED TROPICAL DISEASES

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2012

1935-2735

Background: Growth and maintenance of hydatid cysts produced by Echinococcusgranulosus will have a high requirement for host lipids for energy metabolism, membranebuilding and possibly cellular and developmental signalling. This will require a high degreeof lipid trafficking facilitated by lipid transporter proteins. Members of the fatty acid bindingprotein (FABP) family have been identified in Echinococcus granulosus, one of which,EgFABP1 is expressed at the tegumental level in the protoscolices, but it is also present inboth hydatid cyst fluid and in secretions of protoscolices. In spite of a considerable amountof structural and biophysical information on the FABPs in general, their specific functionsremain mysterious.Methodology/Principal Findings: We have investigated the way in which EgFABP1 mayinteract with membranes using a variety of fluorescence-based techniques and artificialsmall unilamellar vesicles. We first found that bacterial recombinant EgFABP1 is loadedwith fatty acids from the synthesising bacteria, and that fatty acid binding causes subtleconformational changes in the protein that increase its resistance to proteinases. Bymanipulating the composition of lipid vesicles and the ionic environment, we found thatEgFABP1 interacts with membranes in a direct contact, collisional, manner to exchangeligand, involving both ionic and hydrophobic interactions, and that the protein can competewith cytochrome c for association with the surface of vesicles.Conclusions/Significance: It is therefore likely that EgFABP1 interacts directly with theparasite?s own membranes, but also with host membranes in the acquisition of lipids, andpossibly also in the delivery of lipids that may affect the parasite?s cellular andimmunological environment.