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Using Microtiter Dish Radiolabeling for Multiple In Vivo Measurements Of Escherichia coli pppGpp Followed by Thin Layer Chromatography
Published on: June 4, 2019
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(p)ppGpp: Magic Modulators of Bacterial Physiology and Metabolism
Wieland Steinchen1, Victor Zegarra1, Gert Bange1
1Department of Chemistry, Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany.
Frontiers in Microbiology
|October 5, 2020
Summary
Bacteria use (p)ppGpp signaling to manage stress, reprogramming cellular functions. This stringent response is a graded process, not an all-or-nothing switch, allowing adaptation and survival.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bacteria synthesize (p)ppGpp under stress via RelA/SpoT homology (RSH) proteins.
- High (p)ppGpp levels trigger the stringent response, a global cellular reprogramming.
- The stringent response involves downregulation of rRNA/tRNA synthesis and upregulation of stress genes.
Purpose of the Study:
- To investigate the concentration-dependent modulation of (p)ppGpp targets.
- To challenge the 'all-or-nothing' paradigm of the stringent response.
- To propose a prioritization scheme for (p)ppGpp's regulatory effects.
Main Methods:
- Analysis of reported binding affinities of (p)ppGpp to its targets.
- Depiction of a prioritization scheme for (p)ppGpp modulation.
- Comparison of dissociation constants with intracellular (p)ppGpp concentrations.
Main Results:
- Binding affinities of (p)ppGpp targets span a wide range (micromolar to millimolar).
- (p)ppGpp's modulation of targets occurs along a concentration continuum, not an abrupt switch.
- Nucleotide metabolism enzymes are prioritized targets, followed by DNA replication.
Conclusions:
- The stringent response is a graded, concentration-dependent process.
- (p)ppGpp's "magic" lies in its ability to prioritize targets for adaptation.
- This prioritization aids microbial survival and recovery from stress.
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