Membrane protein carbonylation of Plasmodium falciparum infected erythrocytes under conditions of sickle cell trait and G6PD deficiency

Abstract

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) and sickle cell trait (SCT) are described as the polymorphic disorders prevalent in erythrocytes. Both are considered the result of the selective pressure exerted by Plasmodium parasites over human genome, due to a certain degree of resistance to the clinical symptoms of severe malaria. There exist in both a prooxidant environment that favors the oxidative damage on membrane proteins, which probably is part of molecular protector mechanisms. Nevertheless, mechanisms are not completely understood at molecular level for each polymorphism yet, and even less if are commons for several of them. Here, synchronous cultures at high parasitemia levels of P. falciparum 3D7 were used to quantify oxidative damage in membrane proteins of erythrocytes with G6PD deficient and SCT. Carbonyl index by dot blot assay was used to calculate the variation of oxidative damage during the asexual phases. Besides, protein carbonylation profiles were obtained by Western blot and complemented with mass spectrometry using MALDI-TOF-TOF analysis. Erythrocytes with G6PD deficient and SCT showed higher carbonyl index values than control and similar profiles of carbonylated proteins; moreover, cytoskeletal and stress response proteins were identified as the main targets of oxidative damage. Therefore, both polymorphisms promote carbonylation on the same membrane proteins. Finally, these results allowed to reinforce the hypothesis of oxidative damage in erythrocyte membrane proteins as molecular mechanism of human adaptation to malaria infection.

Keywords: Cytoskeletal membrane proteins; G6PD deficiency; Malaria; P. falciparum; Protein carbonylation; Sickle cell trait.