Differential Inhibition of Human and Trypanosome Ubiquitin E1S by TAK-243 Offers Possibilities for Parasite Selective Inhibitors.

Novel strategies to target Trypanosoma brucei, Trypanosoma cruzi and Leishmania are urgently needed to generate better and safer drugs against Human African Trypanosomiasis, Chagas disease and Leishmaniasis, respectively. Here, we investigated the feasibility of selectively targeting in trypanosomatids the ubiquitin E1 activating enzyme (UBA1), an essential eukaryotic protein required for protein ubiquitination. Trypanosomatids contain two UBA1 genes in contrast to mammals and yeast that only have one, and using T. brucei as a model system, we show that both are active in vitro. Surprisingly, neither protein is inhibited by TAK-243, a potent inhibitor of human UBA1. This resistance stems from differences with the human protein at key amino acids, which includes a residue termed the gatekeeper because its mutation in E1s leads to resistance to TAK-243 and related compounds. Importantly, our results predict that trypanosomatid selective UBA1 inhibition is feasible and suggest ways to design novel compounds to achieve this.