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

FRUTTERO, L.L.; LEYRIA, J.; LIGABUE-BRAUN, R.; CLOP, P.; PERILLO, M.A.; CARLINI, C.R.; ARRESE, E.L.; SOULAGES, J.L.; CANAVOSO, L.E.

Orlando, FL

Congreso; XXV International Congress of Entomology; 2016

ENTOMOLOGICAL SOCIETY OF AMERICA

Lipophorin (Lp), the main insect lipoprotein, is involved in the process of lipid transfer from the hemolymph to tissues. In this context, our group has recently that the beta-chain of the ATP synthase complex (beta-ATPase), located in the plasma membrane of the enterocytes of the hematophagous insect Panstrongylus megistus, binds Lp and plays a role as a non-endocytic receptor. The aim of this work was to gather new information regarding the physiological function of beta-ATPase in insect lipid metabolism, focusing in lipid delivery to ovarian tissue. To analyze the effect of in vivo beta-ATPase blocking on lipid transfer from Lp to oocytes, vitellogenic females of P. megistus were injected with an anti-beta-ATPase antibody followed by the injection of Lp conjugated with fluorescent tracers. The beta-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 modeling analysis suggested an expected folding and conserved architecture for the subunit. Analytical ultracentrifugation assays using the recombinant beta-ATPase confirmed the Lp binding with a stoichiometry of 1:1. Laser confocal microscopy showed that anti-beta-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 beta-ATPase functioning as a docking Lp receptor in the ovary. 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 beta-ATPase. (Supported by PICT2013-0626).