Trypanosoma brucei: molecular cloning and stage-regulated expression of a malate dehydrogenase localized to the mitochondrion.

African trypanosomes exhibit dramatic developmental changes in carbohydrate and energy metabolism, with cytochrome-mediated respiration playing an important role only in the insect stages. The parasites possess three isozymes of malate dehydrogenase, each of which has a different subcellular localization and, likely, a distinct metabolic role. We have cloned and characterized a cDNA encoding one of these malate dehydrogenases. Epitope tagging and transfection experiments demonstrate that the corresponding protein is localized to the mitochondrion and that an intact amino terminus is required for proper compartmentalization. The abundance of transcript is developmentally regulated, with higher levels in procyclic stage parasites.