The extraordinary mitochondrion and unusual citric acid cycle in Trypanosoma brucei

J. J. Van Hellemond*, F. R. Opperdoes, A. G.M. Tielens

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

67 Citations (Scopus)

Abstract

African trypanosomes are parasitic protozoa that cause sleeping sickness and nagana. Trypanosomes are not only of scientific interest because of their clinical importance, but also because these protozoa contain several very unusual biological features, such as their specially adapted mitochondrion and the compartmentalization of glycolytic enzymes in glycosomes. The energy metabolism of Trypanosoma brucei differs significantly from that of their hosts and changes drastically during the life cycle. Despite the presence of all citric acid cycle enzymes in procyclic insect-stage T. brucei, citric acid cycle activity is not used for energy generation. Recent investigations on the influence of substrate availability on the type of energy metabolism showed that absence of glycolytic substrates did not induce a shift from a fermentative metabolism to complete oxidation of substrates. Apparently, insect-stage T. brucei use parts of the citric acid cycle for other purposes than for complete degradation of mitochondrial substrates. Parts of the cycle are suggested to be used for (i) transport of acetyl-CoA units from the mitochondrion to the cytosol for the biosynthesis of fatty acids, (ii) degradation of proline and glutamate to succinate, (iii) generation of malate, which can then be used for gluconeogenesis. Therefore the citric acid cycle in trypanosomes does not function as a cycle.

Original languageEnglish
Pages (from-to)967-971
Number of pages5
JournalBiochemical Society Transactions
Volume33
Issue number5
DOIs
Publication statusPublished - Nov 2005
Externally publishedYes

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