Biochemical, bioinformatic and biophysical approaches for understanding the role of β-ATPase as a lipophorin receptor in Panstrongylus megistus, a hematophagous vector of Chagas´ disease (Hemiptera: Reduviidae)

FRUTTERO LL; LEYRIA J; LIGABUE-BRAUN; CLOP P; PERILLO MA; CARLINI, C.R.; ARRESE, EL; SOULAGES JL; CANAVOSO LE

Orlando

Congreso; XXV International Congress of Entomology; 2016

Entomological Society of America

Lipophorin, the main insect lipoprotein, is involved in the process of lipid transfer fromthe hemolymph to tissues. In this context, our group has recently reported that the βchain of the ATP synthase complex (β-ATPase),located in the plasma membraneof the enterocytes of the hematophagous insect Panstrongylus megistus, binds lipophorin and plays a role as a non-endocytic receptor. The aim of this work was to gather new information regarding the physiological function of β-ATPase in insect lipid metabolism,focusing in lipid delivery to ovarian tissue. To analyze the effect of in vivo β-ATPase blocking on lipid transfer from lipophorin to oocytes, vitellogenic females of P. megistus were injected with an anti-β-ATPase antibody followed by the injection of lipophorin conjugated with fluorescent tracers. The β-ATPase was sequenced (GenBank: KF724682.1) and investigated from a bioinformatic viewpoint. The molecular phylogeny study resulted in a species tree grouping and the structural modelinganalysis suggested an expected folding and conserved architecture for the subunit. Analytical ultracentrifugation assays using the recombinant β-ATPase confirmed the lipophorin binding with a stoichiometry of 1:1. Laser confocal microscopy showed that anti-β-ATPase antibody significantly impaired the transfer of lipids to developing oocytes. Comparison of experiments at physiological temperature and at 4°C allowed the demonstration of the β-ATPase functioning as a docking lipophorin receptor in the ovary. Altogether, these findings expand our knowledge of lipoprotein receptors in insects and provide insights for future in-depth studies aimed to unravel the mechanism of lipid transfer mediated by the β-ATPase. (Supported by PICT20130626).