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Purification of Extracellular Trypanosomes, Including African, from Blood by Anion-Exchangers (Diethylaminoethyl-cellulose Columns)
Published on: April 6, 2019
Aromatic amino acid catabolism in trypanosomatids
Cristina Nowicki1, Juan J Cazzulo2
1IQUIFIB/Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, CP1113, Argentina.
Summary
Trypanosomes metabolize aromatic amino acids differently than mammals. This study reveals distinct enzymes and pathways in Trypanosoma cruzi, Trypanosoma brucei, and Leishmania mexicana, highlighting diverse evolutionary strategies in these parasites.
Area of Science:
- Biochemistry
- Parasitology
- Molecular Biology
Background:
- Trypanosomatids cause significant human diseases, including sleeping sickness, Chagas disease, and leishmaniasis.
- Aromatic amino acid metabolism in these parasites is simplified compared to mammalian hosts.
- Key enzymes like tyrosine aminotransferase (TAT) and aromatic L-2-hydroxyacid dehydrogenase (AHADH) are involved in this pathway.
Purpose of the Study:
- To investigate the distinct enzymatic mechanisms of aromatic amino acid metabolism in Trypanosoma cruzi.
- To compare these mechanisms with those in related trypanosomatids like Trypanosoma brucei and Leishmania mexicana.
- To understand the evolutionary divergence of metabolic pathways in these parasitic eukaryotes.
Main Methods:
- Enzyme characterization and substrate specificity analysis of TAT and AHADH in T. cruzi.
- Comparative sequence analysis of enzymes across different trypanosomatid species.
- Investigation of malate dehydrogenase (MDH) isozyme distribution in T. cruzi, T. brucei, and Leishmania spp.
Main Results:
- T. cruzi possesses a unique TAT with altered substrate specificity and an AHADH lacking malate dehydrogenase activity.
- A specific amino acid substitution (Ala102 to Arg) in T. cruzi AHADH dictates its substrate specificity.
- Differential distribution of cytosolic MDH isozymes exists among T. cruzi, T. brucei, and Leishmania spp.
- Leishmania mexicana utilizes a different aminotransferase and appears to lack a T. cruzi AHADH equivalent.
Conclusions:
- Trypanosomatids have evolved distinct enzymatic systems for aromatic amino acid catabolism.
- These differences suggest varied metabolic roles and evolutionary trajectories for these parasitic organisms.
- Understanding these pathways offers insights into potential therapeutic targets for trypanosome-caused diseases.
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