Establishing Virulence Associated Polyphosphate Kinase 2 as a drug target for Mycobacterium tuberculosis

Sci Rep. 2016 Jun 9;6:26900. doi: 10.1038/srep26900.

Abstract

Inorganic polyphosphate (PolyP) plays an essential role in microbial stress adaptation, virulence and drug tolerance. The genome of Mycobacterium tuberculosis encodes for two polyphosphate kinases (PPK-1, Rv2984 and PPK-2, Rv3232c) and polyphosphatases (ppx-1, Rv0496 and ppx-2, Rv1026) for maintenance of intracellular PolyP levels. Microbial polyphosphate kinases constitute a molecular mechanism, whereby microorganisms utilize PolyP as phosphate donor for synthesis of ATP. In the present study we have constructed ppk-2 mutant strain of M. tuberculosis and demonstrate that PPK-2 enzyme contributes to its ability to cause disease in guinea pigs. We observed that ppk-2 mutant strain infected guinea pigs had significantly reduced bacterial loads and tissue pathology in comparison to wild type infected guinea pigs at later stages of infection. We also report that in comparison to the wild type strain, ppk-2 mutant strain was more tolerant to isoniazid and impaired for survival in THP-1 macrophages. In the present study we have standardized a luciferase based assay system to identify chemical scaffolds that are non-cytotoxic and inhibit M. tuberculosis PPK-2 enzyme. To the best of our knowledge this is the first study demonstrating feasibility of high throughput screening to obtain small molecule PPK-2 inhibitors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Outbred Strains
  • Antitubercular Agents / pharmacology*
  • Bacterial Load
  • Bacterial Proteins / antagonists & inhibitors*
  • Bacterial Proteins / chemistry
  • Drug Evaluation, Preclinical
  • Drug Resistance, Bacterial
  • Female
  • Guinea Pigs
  • Humans
  • Lung / microbiology
  • Lung / pathology
  • Mycobacterium tuberculosis / enzymology*
  • Mycobacterium tuberculosis / growth & development
  • Mycobacterium tuberculosis / pathogenicity
  • Phosphotransferases (Phosphate Group Acceptor) / antagonists & inhibitors*
  • Phosphotransferases (Phosphate Group Acceptor) / chemistry
  • THP-1 Cells
  • Tuberculosis, Pulmonary / drug therapy*
  • Tuberculosis, Pulmonary / microbiology
  • Virulence

Substances

  • Antitubercular Agents
  • Bacterial Proteins
  • Phosphotransferases (Phosphate Group Acceptor)
  • polyphosphate kinase