Oligomycin-sensitivity of hexose-sugar catabolism in the bloodstream form of Trypanosoma brucei brucei

Abstract

The catabolism of hexose sugars and glycerol by the bloodstream form of Trypanosoma brucei brucei incubated with oligomycin was investigated. Oligomycin at a concentration of 10 micrograms/10(8) trypanosomes inhibited the catabolism of fructose, glucose and mannose by 70-80%, but not that of glycerol. Permeabilization of the trypanosome membranes by digitonin did not reverse the inhibition by oligomycin. Oligomycin did not inhibit pyruvate production in digitonin-permeabilized trypanosomes which were catabolizing exogenous glycolytic intermediates. It is concluded that the oligomycin-sensitive glycolysis is dependent on trypanosome membrane integrity. Oligomycin caused a rapid increase in the levels of hexose phosphates and some triose phosphates, but a decrease in the levels of glycerate 2-phosphate and phosphoenolpyruvate. There was a crossover point in the sequence of reactions between the formation of glycerol 3-phosphate and glycerate 2-phosphate during catabolism of the hexoses. Addition of the same concentration of oligomycin caused no change in the levels of glycolytic intermediates during the catabolism of glycerol. It is proposed that the catabolism of hexose sugars requires the transport of glycerol 3-phosphate from the glycosome via a glycerol 3-phosphate carrier which is probably inhibited by a hexose-sugar derivative formed on inhibition of the mitochondrial Mg(2+)-ATPase by oligomycin.