Abstract
Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a Neglected Tropical Disease endemic to 36 African countries, with approximately 70 million people currently at risk for infection. Current therapeutics are suboptimal due to toxicity, adverse side effects, and emerging resistance. Thus, both effective and affordable treatments are urgently needed. The causative agent of HAT is the protozoan Trypanosoma brucei ssp. Annotation of its genome confirms previous observations that T. brucei is a purine auxotroph. Incapable of de novo purine synthesis, these protozoan parasites rely on purine phosphoribosyltransferases to salvage purines from their hosts for the synthesis of purine monophosphates. Complete and accurate genome annotations in combination with the identification and characterization of the catalytic activity of purine salvage enzymes enables the development of target-specific therapies in addition to providing a deeper understanding of purine metabolism in T. brucei. In trypanosomes, purine phosphoribosyltransferases represent promising drug targets due to their essential and central role in purine salvage. Enzymes involved in adenine and adenosine salvage, such as adenine phosphoribosyltransferases (APRTs, EC 2.4.2.7), are of particular interest for their potential role in the activation of adenine and adenosine-based pro-drugs. Analysis of the T. brucei genome shows two putative aprt genes: APRT1 (Tb927.7.1780) and APRT2 (Tb927.7.1790). Here we report studies of the catalytic activity of each putative APRT, revealing that of the two T. brucei putative APRTs, only APRT1 is kinetically active, thereby signifying a genomic misannotation of Tb927.7.1790 (putative APRT2). Reliable genome annotation is necessary to establish potential drug targets and identify enzymes involved in adenine and adenosine-based pro-drug activation.
Highlights
Trypanosoma brucei ssp. is the etiological agent of Human African Trypanosomiasis (HAT), known as sleeping sickness
AInitial velocity data were fit to Eq (2) to afford kinetic parameters. bData for Leishmania donovani adenine phosphoribosyltransferase (APRT) (LdAPRT) obtained by Bashor et al, 2002 cData for Giardia lamblia APRT (GlAPRT) obtained by Sarver et al, 2002
The possibility of a post-translational modification (PTM) as a modulator of APRT activity was investigated, and APRT2 was shown to be unresponsive to methionine sulfoxide (MetO) modifications as indicated by the lack of increased activity in the M to Q mutants (APRT2 M73Q, APRT2 M128Q, and APRT2 M156Q) (Figs 7 and S16)
Summary
Trypanosoma brucei ssp. is the etiological agent of Human African Trypanosomiasis (HAT), known as sleeping sickness. Is the etiological agent of Human African Trypanosomiasis (HAT), known as sleeping sickness. Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense cause, respectively, chronic and acute forms of this disease in humans [1,2], for which the chronic infection is more prevalent (> 90% of reported cases) [3]. HAT presents initial symptoms of headache, fever, and fatigue; and is mainly transmitted horizontally by the vector tsetse flies of the genus Glossina [4], and vertically from mother to offspring [5], with evidence of sexual transmission [6]. Once in the central nervous system (CNS), the parasites alter sleeping habits, cause mood swings, impairment of reasoning and mental processing, followed by coma and death if untreated [7–9]. Progression of HAT leads to demyelination in the CNS, making it impossible to cure even after clearance of parasites [1]. HAT is endemic to 36 African countries; threatening an estimated 70 million people [3,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
