Discussion

The survival of Trypanosoma brucei depends on maintenance and function of the mitochondrial genome (kinetoplast, or kDNA). However, a single point mutation in subunit γ of the mitochondrial F1FO ATPase can abolish the requirement of kDNA for survival of the bloodstream form of the parasite (Dean et al., 2013), and it was found that genetic or chemical inhibition of the vacuolar ATPase (V-ATPase) could have a similar effect (Baker et al., 2015). Here we present detailed studies of the effects of V-ATPase inhibitors on parasite growth after genetic or chemical interference with kDNA function. We found that treating bloodstream form T. brucei cells with bafilomycin A1 fully rescued loss of viability induced by depletion of the essential RNA editing ligase REL1. This confirmed a connection between V-ATPase function and kinetoplast dependency and suggests that V-ATPase inhibitors could be used as chemical tools in the study of kinetoplast biology. However, only limited rescue of the growth phenotype was found upon addition of bafilomycin A1 to cells treated with a low concentration of ethidium bromide that caused specific kinetoplast loss. Furthermore, this rescue was not robust beyond 3 days. Work to explain these seemingly contradictory data is in progress and will also be presented at the meeting.