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The Non‐Canonical Substrates of Trypanosoma cruzi Tyrosine and Aspartate Aminotransferases: Branched‐Chain Amino Acids
Author(s) -
Manchola Nubia Carolina,
Silber Ariel Mariano,
Nowicki Cristina
Publication year - 2017
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/jeu.12435
Subject(s) - biology , trypanosoma cruzi , biochemistry , amino acid , tyrosine , isoleucine , leucine , enzyme , chagas disease , branched chain amino acid , catabolism , parasite hosting , virology , computer science , world wide web
Trypanosoma cruzi, the etiological agent of Chagas disease, lacks genes that encode canonical branched‐chain aminotransferases. However, early studies showed that when epimastigotes were grown in the presence of 14 C 1 ‐ DL ‐leucine, the label was incorporated into various intermediates. More recently, our studies provided evidence that T. cruzi epimastigotes display a single ATP ‐dependent and saturable transport system that enables epimastigotes to uptake branched‐chain amino acids ( BCAA s) from the culture media. To extend our knowledge of the first step of BCAA catabolism, the ability of this parasite's noncanonical broad specificity aminotransferases, such as tyrosine aminotransferase ( TAT ) and aspartate aminotransferase ( ASAT ), to transaminate these amino acids was investigated. Indeed, our results show that TAT and ASAT utilize BCAA s as substrates; however, both enzymes differ in their catalytic competence in utilizing these amino donors. For instance, ASAT transaminates isoleucine nearly 10‐fold more efficiently than does TAT . This unique characteristic of TAT and ASAT allows to explain how BCAA s can be oxidized in the absence of a BCAA transaminase in T. cruzi .