NON-CYTOCHROME MEDIATED MITOCHONDRIAL ATP PRODUCTION IN BLOOD-STREAM FORM TRYPANOSOMA-BRUCEI-BRUCEI

The life cycle of Trypanosoma brucei brucei involves a series of diffe rentiation steps characterized by marked changes in mitochondrial deve lopment and function. The bloodstream forms of this parasite completel y lack cytochromes and have not been considered to have any Krebs cycl e function. It has been suggested that glycolysis is the sole source o f ATP in all bloodstream forms. However, earlier results indicated tha t in the mitochondria of the transitional intermediate/short stumpy bl oodstream forms, the biochemical pathways are present that could allow intra-mitochondrial production of ATP. Using a high mannitol buffer t o enhance permeability, we confirm previous observations showing that transitional forms maintain motility and respiratory activity with 2-o xoglutarate as the sole substrate. Using a luminometer to measure intr acellular ATP levels via the luciferin/luciferase chemiluminescence as say, we show that these same transitional forms, but not long slender forms, maintain high levels of intracellular ATP in the presence of 2- oxoglutarate. Further, in the presence of bongkrekic acid, an inhibito r of the mitochondrial adenine nucleotide translocase, ATP levels are reduced with subsequent death and lysis of the cells when 2-oxoglutara te, but not glucose, is used as sole substrate. These data are direct evidence of ATP production by transitional bloodstream form mitochondr ia.