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Assaying for Inorganic Polyphosphate in Bacteria
07:20

Assaying for Inorganic Polyphosphate in Bacteria

Published on: January 21, 2019

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MglA/SspA complex interactions are modulated by inorganic polyphosphate

Algevis P Wrench1, Christopher L Gardner, Sara D Siegel

  • 1Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida, United States of America.

Plos One
|October 12, 2013
PubMed

Insights

Inorganic polyphosphate (polyP) acts as a crucial signal molecule, enhancing the interaction between MglA and SspA in Francisella tularensis. This polyP-mediated interaction is vital for the pathogen

Area of Science:

  • Microbiology and Molecular Biology
  • Bacterial Pathogenesis
  • Gene Regulation

Background:

  • Francisella tularensis virulence relies on Francisella pathogenicity island (FPI) genes.
  • MglA and SspA transcription factors form a heterodimer complex essential for FPI gene regulation.
  • The role of intracellular metabolites in modulating MglA-SspA protein interactions was unknown.

Purpose of the Study:

  • To investigate if intracellular metabolites modulate the MglA-SspA protein/protein interactions.
  • To identify the specific metabolite responsible for promoting MglA-SspA complex formation and function.

Main Methods:

  • Yeast two-hybrid system in a polyphosphate-deficient Escherichia coli strain.
  • Chromatin immunoprecipitation (ChIP) studies in F. tularensis.
  • Isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC) to assess binding affinity and stability.

Main Results:

  • Inorganic polyphosphate (polyP) was identified as a signal molecule promoting MglA-SspA interaction.
  • PolyP stabilizes the MglA/SspA complex and its interaction with the FevR regulator.
  • PolyP directly binds to the MglA/SspA complex with high affinity (KD = 0.3 µM), increasing its thermal stability.

Conclusions:

  • Inorganic polyphosphate is a key regulator of MglA-SspA complex formation and function in Francisella tularensis.
  • PolyP enhances the binding of the MglA/SspA complex to target gene promoters, impacting virulence.
  • This discovery provides a novel target for understanding and potentially controlling F. tularensis infections.

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