Inorganic polyphosphate interacts with nucleolar and glycosomal proteins in trypanosomatids

Summary 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, exchan...

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Bibliographic Details
Published in:Molecular microbiology 2018-12, Vol.110 (6), p.973-994
Main Authors: Negreiros, Raquel S., Lander, Noelia, Huang, Guozhong, Cordeiro, Ciro D., Smith, Stephanie A., Morrissey, James H., Docampo, Roberto
Format: Article
Language:English
Subjects:
Binding
Calcium
E coli
Exopolyphosphatase
Fluorescence
Fractionation
Glycolysis
Glycosomes
Immunofluorescence
Knowledge representation
Lysates
Nucleoli
Oxidative stress
Proteins
Protozoa
Target recognition
Volutin granules
Yeast
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Summary:Summary 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. In this work, we report that polyphosphate, a polymer of up to hundreds of phosphates linked by high‐energy bonds, binds to a number of trypanosomal proteins among them proteins localized to the glycosomes, and to the nucleoli. Polyphosphate was localized by a cytochemical technique to the glycosomes and nucleoli of trypanosomes. Targeting of an enzyme that cleaves polyphosphate to the glycosomes resulted in increased consumption of glucose, suggesting an inhibitory effect of polyphosphate on glycolysis.
ISSN:0950-382X
1365-2958
DOI:10.1111/mmi.14131