Abstract
Pyruvate export is an essential physiological process for the bloodstream form of Trypanosoma brucei as the parasite would otherwise accumulate this end product of glucose metabolism to toxic levels. In the studies reported here, genetic complementation in Saccharomyces cerevisiae has been employed to identify a gene (TbPT0) that encodes this vital pyruvate transporter from T. brucei. Expression of TbPT0 in S. cerevisiae reveals that TbPT0 is a high affinity pyruvate transporter. TbPT0 belongs to a clustered multigene family consisting of five members, whose expression is up-regulated in the bloodstream form. Interestingly, TbPT family permeases are related to polytopic proteins from plants but not to characterized monocarboxylate transporters from mammals. Remarkably, inhibition of the TbPT gene family expression in bloodstream parasites by RNAi is lethal, confirming the physiological relevance of these transporters. The discovery of TbPT0 reveals for the first time the identity of the essential pyruvate transporter and provides a potential drug target against the mammalian life cycle stage of T. brucei.
Highlights
Pyruvate transport is vital for growth and survival of T. brucei bloodstream form
Cloning of a Pyruvate Transporter Gene by Genetic Complementation of Pyruvate-auxotrophic Yeast—Pyruvate transport has been characterized in T. brucei BF parasites by biochemical means employing whole cells [6, 13]
Transformants were selected on yeast nitrogen base medium (YNB) agar plates containing 10 mM pyruvate as the sole energy source
Summary
Pyruvate transport is vital for growth and survival of T. brucei bloodstream form. Results: TbPT0 is a unique monocarboxylate transporter with preference for pyruvate and essential for bloodstream form viability. Significance: Unique T. brucei pyruvate transporters provide a potential drug target against the bloodstream form parasites. Pyruvate export is an essential physiological process for the bloodstream form of Trypanosoma brucei as the parasite would otherwise accumulate this end product of glucose metabolism to toxic levels. I report the cloning and functional analysis of a T. brucei gene that encodes a novel pyruvate transporter TbPT0, which belongs to a multigene family of five members arranged in tandem and encoding distinct but very similar proteins. Inhibition of TbPTs expression by RNAi is lethal, underscoring their critical function for survival and their potential as drug targets.
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