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Updated: Oct 5, 2026

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein
11:23

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein

Published on: June 30, 2019

Serine/threonine protein kinases PknF and PknG of Mycobacterium tuberculosis: characterization and localization

Anil Koul1,2,3, Axel Choidas4, Anil K Tyagi2

  • 1Department of Molecular Biology, Max-Planck-Institut für Biochemie, Am Klopferspitz 18A, 82152 Martinsried, Germany5.

Microbiology (Reading, England)
|August 10, 2001
PubMed

Insights

Mycobacterium tuberculosis protein kinases PknF and PknG were characterized. These kinases play a role in mycobacterial pathogenesis, with PknF being transmembrane and PknG cytosolic.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Mycobacterium tuberculosis pathogenesis relies on intracellular survival and replication.
  • Pathogenic bacteria can utilize protein kinases to manipulate host cell signaling networks, enhancing bacterial survival.

Purpose of the Study:

  • To characterize two putative protein kinases, PknF and PknG, encoded by M. tuberculosis H37Rv.
  • To investigate the enzymatic activity, substrate specificity, and cellular localization of PknF and PknG.

Main Methods:

  • Cloning and expression of pknF and pknG genes in Escherichia coli.
  • Purification and biochemical characterization of PknF and PknG, including substrate phosphorylation assays.
  • Site-directed mutagenesis to assess the role of the ATP-binding site.
  • Southern blot analysis for gene homolog detection across different mycobacterial species.
  • Immunoblot analysis to determine the cellular localization of PknF and PknG.

Main Results:

  • Purified PknF phosphorylated myelin basic protein (MBP) at serine and threonine residues.
  • Purified PknG phosphorylated MBP exclusively at serine residues.
  • Kinase activity for both PknF and PknG was dependent on the conserved ATP-binding-site lysine residue.
  • Homologues of pknF and pknG were found in M. tuberculosis H37Ra and Mycobacterium bovis BCG, but not in Mycobacterium smegmatis.
  • PknF was identified as a transmembrane protein, while PknG was found to be predominantly cytosolic in M. tuberculosis H37Rv.

Conclusions:

  • PknF and PknG are functional protein kinases in M. tuberculosis.
  • The distinct substrate specificities and cellular localizations suggest specialized roles for PknF and PknG in mycobacterial physiology.
  • These findings provide insights into the potential contribution of PknF and PknG to the pathogenesis of mycobacteria.

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