title: β-chain of ATP synthase as a lipophorin binding protein and its role in lipid transfer in the midgut of Panstrongylus megistus (Hemiptera: Reduviidae).
abstract: Lipophorin, the main lipoprotein in the circulation of the insects, cycles among peripheral tissues to exchange its lipid cargo at the plasma membrane of target cells, without synthesis or degradation of its apolipoprotein matrix. Currently, there are few characterized candidates supporting the functioning of the docking mechanism of lipophorin-mediated lipid transfer. In this work we combined ligand blotting assays and tandem mass spectrometry to characterize proteins with the property to bind lipophorin at the midgut membrane of Panstrongylus megistus, a vector of Chagas' disease. We further evaluated the role of lipophorin binding proteins in the transfer of lipids between the midgut and lipophorin. The β subunit of the ATP synthase complex (β-ATPase) was identified as a lipophorin binding protein. β-ATPase was detected in enriched midgut membrane preparations free of mitochondria. It was shown that β-ATPase partially co-localizes with lipophorin at the plasma membrane of isolated enterocytes and in the sub-epithelial region of the midgut tissue. The interaction of endogenous lipophorin and β-ATPase was also demonstrated by co-immunoprecipitation assays. Blocking of β-ATPase significantly diminished the binding of lipophorin to the isolated enterocytes and to the midgut tissue. In vivo assays injecting the β-ATPase antibody significantly reduced the transfer of [(3)H]-diacylglycerol from the midgut to the hemolymph in insects fed with [9,10-(3)H]-oleic acid, supporting the involvement of lipophorin-β-ATPase association in the transfer of lipids. In addition, the β-ATPase antibody partially impaired the transfer of fatty acids from lipophorin to the midgut, a less important route of lipid delivery to this tissue. Taken together, the findings strongly suggest that β-ATPase plays a role as a docking lipophorin receptor at the midgut of P. megistus.
authors: Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Facultad de Ciencias Químicas-Universidad Nacional de Córdoba, Córdoba, CP 5000, Argentina.
authors: Leonardo L
authors: LL
authors: Fruttero
authors: Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors: Diogo R
authors: DR
authors: Demartini
authors: Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Facultad de Ciencias Químicas-Universidad Nacional de Córdoba, Córdoba, CP 5000, Argentina.
authors: Edilberto R
authors: ER
authors: Rubiolo
authors: Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Department of Biophysics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors: Célia R
authors: CR
authors: Carlini
authors: Departamento de Bioquímica Clínica, Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Facultad de Ciencias Químicas-Universidad Nacional de Córdoba, Córdoba, CP 5000, Argentina. Electronic address: lcanavo@mail.fcq.unc.edu.ar.
authors: Lilián E
authors: LE
authors: Canavoso
mesh_terms: D025181:ATP Synthetase Complexes / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism*; D004064:Digestive System / Q000378:metabolism*; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000378:metabolism*; D010203:Panstrongylus / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D002352:Carrier Proteins; D008074:Lipoproteins; C032830:lipophorin; D025181:ATP Synthetase Complexes
keywords: Lipid metabolism; Lipophorin receptors; Midgut; Triatominae; β-chain of ATP synthase