Trypanosoma cruzi protein lipoilation pattern is modified by the lipoate biosynthesis/salvage inhibitor 8-bromo-octanoate and its methyl derivative

VACCHINA P; LAMBRUSCHI DA; UTTARO AD

Buenos Aires

Congreso; XXVII Reunión anual de la SAP; 2015

Lipoic acid (LA) is a versatile compound that acts as a cofactor of the α-ketoacid dehydrogenase complexes (α-KADHs) and of the glycine cleavage complex (GCC). As these enzymatic complexes are essential to the cell, LA biosynthesis and the protein lipoilation mechanism are potential chemotherapeutic candidates against parasites as Trypanosoma cruzi and T. brucei. Many organisms have LA salvage pathways by which they scavenge free LA from their environment and lipoilate proteins using lipoate:protein ligase enzymes. We have previously proved that, similar to what is observed in yeast and T. brucei, T. cruzi lacks of an active LA salvage mechanism. As a direct consequence of this we have detected a difference in susceptibility to the treatment with the non-permeable inhibitor 8-bromo-octanoate (BrO) versus the permeable methyl-bromo-octanoate (MBrO). While T. cruzi epimastigote cultures incubated with BrO presented an EC50 value of 1mM, parasites treated with MBrO required 10 times less drug (100 µM) to show the same deleterious effect. A notable result of both treatments was the drastic reduction of lipoilated proteins, although the reduction was more important in parasite extracts obtained after MBrO incubation. In addition, we have observed that the T. cruzi protein lipoliation pattern can be regulated by growth conditions. Altogether, our results support the hypothesis that LA metabolism is essential for the parasite survival and validates the lipoliation pathway as new drug target.