Related Experiment Video

Updated: Jun 27, 2026

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies
07:56

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies

Published on: September 3, 2012

Regulation of glutamate metabolism by protein kinases in mycobacteria

Helen M O'Hare1, Rosario Durán, Carlos Cerveñansky

  • 1Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland. hmo7@le.ac.uk

Molecular Microbiology
|November 21, 2008
PubMed

Insights

Mycobacterium tuberculosis protein kinase G (PknG) phosphorylates GarA, affecting glutamate metabolism and virulence. This distinct autophosphorylation pattern regulates GarA binding and enzyme activity, impacting the TCA cycle.

Area of Science:

  • Microbiology
  • Biochemistry
  • Molecular Biology

Background:

  • Mycobacterium tuberculosis protein kinase G (PknG) is linked to virulence and glutamate metabolism.
  • Understanding PknG's regulatory mechanisms is crucial for targeting tuberculosis.

Purpose of the Study:

  • To investigate the autophosphorylation pattern of PknG.
  • To identify substrates of PknG and elucidate their role in cellular processes.
  • To understand the interplay between PknG, GarA, and metabolic enzymes.

Main Methods:

  • Characterization of PknG autophosphorylation.
  • Identification of GarA as a PknG substrate.
  • Analysis of GarA phosphorylation by PknB.
  • Enzyme activity assays for alpha-ketoglutarate decarboxylase and glutamate dehydrogenase.

Main Results:

  • PknG exhibits a unique autophosphorylation pattern distinct from other M. tuberculosis kinases.
  • GarA is identified as a direct substrate of PknG, phosphorylated at threonine 21.
  • PknG autophosphorylation enhances GarA binding, an interaction observed in vivo.
  • Phosphorylation events by PknG and PknB on GarA are mutually exclusive.
  • Unphosphorylated GarA inhibits alpha-ketoglutarate decarboxylase and modulates glutamate dehydrogenase activity.
  • These GarA-mediated effects explain previously observed glutamate metabolism defects in pknG deletion mutants.

Conclusions:

  • PknG regulates GarA phosphorylation, impacting key enzymes in the TCA cycle and glutamate metabolism.
  • The PknG-GarA interaction is a potential target for modulating M. tuberculosis virulence.
  • Understanding these molecular mechanisms provides insights into host-pathogen interactions and potential therapeutic strategies.

More Related Videos

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria09:01

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria

Published on: January 7, 2022

Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains06:45

Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains

Published on: January 18, 2014

Related Concept Videos

cAMP-dependent Protein Kinase Pathways01:25

cAMP-dependent Protein Kinase Pathways

Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Regulation of Metabolism01:19

Regulation of Metabolism

Cellular needs and conditions vary from cell to cell and change within individual cells over time. For example, the required enzymes and energetic demands of stomach cells are different from those of fat storage cells, skin cells, blood cells, and nerve cells. Furthermore, a digestive cell works much harder to process and break down nutrients during the time that closely follows a meal compared with many hours after a meal. As these cellular demands and conditions vary, so do the amounts and...
Protein Kinases and Phosphatases02:54

Protein Kinases and Phosphatases

Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis are various protein modifications that regulate protein activity. Such modifications are usually enzyme-driven.
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a rapamycin-insensitive companion...
Regulated Protein Degradation02:58

Regulated Protein Degradation

It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...