Genetic and chemical analyses reveal that trypanothione synthetase but not glutathionylspermidine synthetase is essential for Leishmania infantum.

摘要: Abstract Trypanothione is a unique and essential redox metabolite of trypanosomatid parasites, the biosynthetic pathway which regarded as promising target for antiparasitic drugs. Synthesis trypanothione occurs by consecutive conjugation two glutathione molecules to spermidine. Both reaction steps are catalyzed synthetase (TRYS), molecule known be in Trypanosoma brucei. However, other trypanosomatids (including some Leishmania species cruzi) potentially express one additional enzyme, glutathionylspermidine (GSPS), capable driving first step synthesis yielding glutathionylspermidine. Because this monothiol can substitute reactions, possibility existed that TRYS was redundant parasites harboring GSPS. To clarify issue, functional relevance both GSPS investigated infantum (Li). Employing gene-targeting approach, we generated gsps−/− knockout line, viable replicating life cycle stages parasite, thus demonstrating superfluous role LiGSPS. In contrast, elimination LiTRYS alleles not possible unless were previously complemented with an episomal copy gene. Retention extrachromosomal trys−/−/+TRYS line after several passages culture further supported essentiality gene survival L. its clinically relevant stage), hence ruling out hypothesis complementation Chemical targeting drug-like compound shown also lead parasite death. Overall, study disqualifies drug development campaigns and, genetic chemical evidence, validates chemotherapeutic endowed thus, probably along entire lineage.