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Mol Microbiol. 2018 Dec;110(6):973-994. doi: 10.1111/mmi.14131. Epub 2018 Oct 18.

Inorganic polyphosphate interacts with nucleolar and glycosomal proteins in trypanosomatids.

Author information

1
Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.
2
Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
3
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, 48109, 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.

PMID:
30230089
PMCID:
PMC6281790
DOI:
10.1111/mmi.14131
[Indexed for MEDLINE]
Free PMC Article

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