Biosynthesis of 5-aminolevulic acid in trypanosoma cruzi

Abstract

Trypanosoma cruzi requires heme-compounds for growing, due to its partially or totally deficient biosynthetic pathway of heme. There are reports that support the functionality of mitochondrial enzymes involved in this pathway, such as 5-aminolevúlico synthetase (ALA-S) and Heme synthetase (Heme-S). T. cruzi genome is known and two homologous genes, Tc00.1047053511899.40 y Tc00.1047053511071.140, were identified by bioinformatic studies. Both of them are candidates to code with high score (50%) for the ALA-S enzyme, responsible for synthesizing ALA from succinyl CoA and glycine. Our hypothesis is that the parasite is able to synthesize ALA (although it cannot be metabolized to heme) and the Tc00.1047053511899.40 y Tc00.1047053511071.140 sequences encodes for a protein with ALA-S activity. Using epimastigotes, we were able to detect and quantify, by spectrophotometric studies and HPLC chromatography, the presence of ALA in the parasite both intra and extracellularly. The mesasurements were made in 30ml of parasite culture which yielded about 608,31 ± 45,20 nmol of ALA. The extracellular content represents 96% of the total synthesized. Such excretion would be avoiding the citotoxicity of ALA since it cannot be metabolized to heme From bioinformatic studies using the Blast, ORF Finder, Mitoprop, Prosite and ClustalW platforms, it was determined that the above genes would code for a mitochondrial protein (98%) which is dependent on pyridoxal phosphate and shown a KBL domain, which is characteristic of enzymes as ALA-S. Both, ALA detection and the computer analysis would support our hypothesis and encourages us to continue trying to confirm it.