Gluconeogenesis is essential for trypanosome development in the tsetse fly vector

Area of Science:

• Parasitology
• Molecular Biology
• Biochemistry

Background:

• Procyclic Trypanosoma brucei in tsetse flies rely on proline for energy in a glucose-free environment.
• Parasite survival necessitates gluconeogenesis to produce glucose 6-phosphate (G6P) from non-glycolytic carbon sources.

Purpose of the Study:

• To investigate the enzymes and pathways involved in gluconeogenesis for G6P production in procyclic T. brucei.
• To determine the essentiality of specific gluconeogenic enzymes for parasite viability and development in the tsetse fly vector.

Main Methods:

• Gene deletion and RNA interference (RNAi) to create null mutants (Δppdk/Δpepck, Δfbpase) and down-regulate gene expression.
• 13C-enriched proline incorporation assays to trace carbon flow into G6P.
• In vitro differentiation assays and in vivo colonization studies in tsetse flies.

Main Results:

• PEP carboxykinase (PEPCK) and pyruvate phosphate dikinase (PPDK) exhibit redundant roles in proline-derived G6P synthesis.
• Glycerol kinase is crucial for gluconeogenesis when PEPCK and PPDK are absent.
• Fructose-1,6-bisphosphatase (FBPase) is essential for T. brucei colonization of the tsetse fly salivary glands and metacyclic stage differentiation, despite its non-essentiality for in vitro G6P production from proline.

Conclusions:

• Procyclic T. brucei employs redundant pathways (PEPCK/PPDK) and glycerol metabolism for gluconeogenesis.
• FBPase is a critical determinant for the in vivo development and infectivity of T. brucei within the tsetse fly vector.
• Understanding these metabolic pathways offers potential targets for controlling trypanosomiasis.