Ppgpp Effect
Ppgpp Effect - Related Videos
09:53
A Purification and In Vitro Activity Assay for a (p)ppGpp Synthetase from Clostridium difficile
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Cited by 3 •
2018
Here, we describe a method for purifying histidine-tagged pyrophosphokinase enzymes and utilizing thin layer chromatography of radiolabelled substrates and products to assay for the enzymatic activity in vitro. The enzyme activity assay is broadly applicable to any kinase, nucleotide cyclase, or phosphor-transfer reaction whose mechanism includes nucleotide triphosphate hydrolysis.
06:30
Using Microtiter Dish Radiolabeling for Multiple In Vivo Measurements Of Escherichia coli (p)ppGpp Followed by Thin Layer Chromatography
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Cited by 3 •
2019
The growth of radiolabeled bacterial cultures in microtiter dishes facilitates high throughput sampling that allows multiple technical and biological replicate assays of nucleotide pool abundance, including that of (p)ppGpp. The effects of growth transitions provoked by sources of physiological stress as well as recovery from stress can be monitored.
02:43
Thin-Layer Chromatography-Based Separation of (p)ppGpp Nucleotides Isolated from Stress-Induced Bacteria
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2025
Source: Fernández-Coll, L. and Cashel, M. Using Microtiter Dish Radiolabeling for Multiple In Vivo Measurements Of Escherichia coli (p)ppGpp Followed by Thin Layer Chromatography. J. Vis. Exp. (2019)This video presents a high-throughput protocol for measuring the levels and dynamics of the bacterial stress-response nucleotides ppGpp and pppGpp using thin-layer chromatography (TLC). The method provides a powerful, rapid, and cost-effective approach to quantifying (p)ppGpp in bacterial cultures...
10:42
Flow Cytometric Analysis of Particle-bound Bet v 1 Allergen in PM10
0 Views •
Cited by 8 •
2016
Here, we present a protocol to quantify allergen-loaded particles by flow cytometry. Ambient particulate matter particles may act as carriers of adsorbed allergens. We show here that flow cytometry, a method widely used to characterize suspended solids >0.5 µm in diameter, can be used to measure these allergen-loaded particles.
10:24
Quantitation of Endothelial Cell Adhesiveness In Vitro
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Cited by 10 •
2015
We report an in vitro method that allows the quantitation of the actual number of adhesive cells within an endothelial cell monolayer.
FAQs
The balance between synthesis and degradation determines how quickly ppGpp levels rise, fall, or remain elevated. RelA and SpoT-like enzymes therefore provide a flexible control point rather than a fixed switch. This changing concentration allows bacterial cells to adjust their regulatory state as nutrient limitation or other stresses develop and then change.
ppGpp does not act only by changing its own concentration; it works with regulatory proteins and RNA polymerase to redirect transcription. This interaction changes which cellular programs receive transcriptional priority during stress. The result is a coordinated shift away from growth-associated biosynthesis and toward functions that support adaptation.
During nutrient limitation, ppGpp helps bacteria balance immediate survival with continued cellular growth. Its regulatory effects reduce growth-associated biosynthesis, limiting investment in processes that depend on abundant resources. At the same time, transcriptional redirection supports stress adaptation, allowing the cell to reorganize metabolism rather than simply continuing a growth program that conditions no longer support.
Changes in ppGpp regulation can influence metabolism, ribosome production, persistence, and overall growth behavior. These outcomes reflect the broad reach of the stringent response across bacterial physiology rather than a single pathway. Examining them together helps researchers determine how a stress signal is translated into altered cellular priorities and survival-related states.
A change in ppGpp concentration should be interpreted alongside the activities of RelA and SpoT-like enzymes and the resulting transcriptional effects. Increased or decreased levels indicate that the balance between synthesis and degradation has shifted, but the biological meaning depends on how that shift affects growth-associated biosynthesis, metabolism, ribosome production, or adaptation.
The response connects bacterial stress regulation with persistence, stress-resistant infections, and interactions with hosts. Understanding how ppGpp redirects physiology can therefore identify regulatory features that help bacteria withstand unfavorable conditions. This knowledge informs research on antimicrobial strategies by focusing attention on the systems that balance survival, growth, and adaptation during infection-related stress.