Related Experiment Video
Updated: Feb 5, 2026

Assaying for Inorganic Polyphosphate in Bacteria
Published on: January 21, 2019
Inorganic polyphosphate interacts with nucleolar and glycosomal proteins in trypanosomatids
Raquel S Negreiros1, Noelia Lander1,2, Guozhong Huang1
1Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
Abstract:
Inorganic polyphosphate (polyP) is a polymer of three to hundreds of phosphate units bound by high-energy phosphoanhydride bonds and present from bacteria to humans. Most polyP in trypanosomatids is concentrated in acidocalcisomes, acidic calcium stores that possess a number of pumps, exchangers, and channels, and are important for their survival. In this work, using polyP as bait we identified > 25 putative protein targets in cell lysates of both Trypanosoma cruzi and Trypanosoma brucei. Gene ontology analysis of the binding partners found a significant over-representation of nucleolar and glycosomal proteins. Using the polyphosphate-binding domain (PPBD) of Escherichia coli exopolyphosphatase (PPX), we localized long-chain polyP to the nucleoli and glycosomes of trypanosomes. A competitive assay based on the pre-incubation of PPBD with exogenous polyP and subsequent immunofluorescence assay of procyclic forms (PCF) of T. brucei showed polyP concentration-dependent and chain length-dependent decrease in the fluorescence signal. Subcellular fractionation experiments confirmed the presence of polyP in glycosomes of T. brucei PCF. Targeting of yeast PPX to the glycosomes of PCF resulted in polyP hydrolysis, alteration in their glycolytic flux and increase in their susceptibility to oxidative stress.
Related Concept Videos
Gravimetry: Inorganic And Organic Precipitating Agents
Inorganic Nitrogen Assimilation
Factors Affecting Protein-Drug Binding: Drug Interactions
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...
Protein-protein Interfaces
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme...
Protein Networks
These interactions can be represented through maps depicting protein-protein interaction networks, represented as nodes and edges. Nodes are circles that are representative of a protein,...

