Effects of ethidium bromide on the mitochondrial adenosine triphosphatase from Trypanosoma cruzi.

Culturing of Trypanosoma cruzi in the presence of ethidium bromide (EB; 1.0-2.5 microM), for 5 days, affected the biogenesis of the Fo/F1-ATPase complex, presumably by EB interference with the expression of the putative Fo-sector subunits encoded by maxicircle DNA. In vitro, EB inhibited ATP hydrolysis by the Fo/F1-ATPase complex and also by soluble F1, the former preparation being the most strongly affected (EB I50, 250 microM). Analysis of EB effect at increasing MgATP concentrations, as well as combination of EB and p-chloromercuribenzoate inhibitions, indicated that the dye interacts with ATPase at sites other than the catalytic ones. No correlation was found between the in vitro inhibition of ATPase and EB effect on parasite growth.