Glycolysis in Trypanosoma brucei.

Area of Science:

• Biochemistry
• Cell Biology
• Parasitology

Background:

• Trypanosoma brucei bloodstream forms utilize glycolysis for energy.
• Glycosomes are unique organelles in trypanosomes, containing enzymes for glycolysis.
• The compartmentalization of glycolytic intermediates within glycosomes was previously unclear.

Purpose of the Study:

• To investigate if glycosomes in Trypanosoma brucei represent a separate pool of glycolytic intermediates.
• To determine the permeability of the glycosomal membrane to glycolytic metabolites and co-factors.
• To analyze the impact of respiratory inhibition on glycolytic intermediate concentrations and cellular redox state.

Main Methods:

• Differential enzyme activation using digitonin titration in intact cells and subcellular fractions.
• Measurement of glycolytic intermediate and adenine nucleotide concentrations under varying conditions.
• Analysis of cellular redox state using NADH/NAD+ couple potential.

Main Results:

• Glycosomal enzymes showed latency, indicating a surrounding membrane acting as a permeability barrier.
• Salicylhydroxamic acid treatment decreased most glycolytic intermediates but increased glycerol-3-phosphate.
• Phosphate potential decreased, and the cellular redox state became more reduced upon respiratory inhibition.

Conclusions:

• Glycosomal enzymes are enclosed by a membrane that restricts the passage of glycolytic intermediates and co-factors.
• Glycolytic intermediates exist in both glycosomes and the cytosol of bloodstream form T. brucei.
• Despite the glycosomal membrane, these two pools of intermediates equilibrate with each other.