Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Stringent Response in E. coli

Stringent Response in E. coli

Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...

DNA Bacteriophages

DNA Bacteriophages

Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...

Bacteriophages of the Human Virome

Bacteriophages of the Human Virome

Bacteriophages are found throughout the human body. They may even outnumber eukaryotic viruses, forming an important and dynamic component of the human virome. Indeed, phages represent the most abundant viral entities, with densities in the gut reaching up to 10⁹ particles per gram of fecal matter, and many belonging to orders such as Caudovirales and Microviridae, while a substantial proportion remains unclassified as viral “dark matter.”Lysogeny and Genetic ExchangeIn the gut, bacteriophages...

Other Stress Responses in Bacteria

Other Stress Responses in Bacteria

Bacteria have global regulatory systems that control several types of stress mechanisms. These include Pho regulon and the heat shock response, which are essential systems for environmental adaptation, such as nutrient limitation and proteotoxic stress. The Pho regulon and the heat shock response exemplify bacterial resilience, enabling rapid adaptation to fluctuating environmental conditions.Pho RegulonBacteria require phosphorus for essential cellular processes, including nucleic acid...

Viral Replication: Lysogenic Cycle

Viral Replication: Lysogenic Cycle

The lysogenic cycle is a crucial viral replication strategy that allows bacteriophages to persist within host cells without immediately destroying them. This process is primarily observed in temperate phages, such as bacteriophage lambda (λ), which infects Escherichia coli. The cycle allows the viral genome to persist across bacterial generations while keeping host cells viable.Integration of the Viral GenomeUpon infection, bacteriophage lambda attaches to the bacterial surface and injects its...

Lysogenic Cycle of Bacteriophages

Lysogenic Cycle of Bacteriophages

In contrast to the lytic cycle, phages infecting bacteria via the lysogenic cycle do not immediately kill their host cell. Instead, they combine their genome with the host genome, allowing the bacteria to replicate the phage DNA along with the bacterial genome. The incorporated copy of the phage genome is called the prophage. Some prophages can re-activate and enter the lytic cycle. This often occurs in response to a perturbation, such as DNA damage, but can also transpire in the absence of...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

A Dual-Functional Biohybrid Nanorobot to Synergistically Eradicate Biofilm and Degrade Antibiotic Resistance Genes.

Advanced science (Weinheim, Baden-Wurttemberg, Germany)·2026

Same author

Mono- and multidomain defense toxins of the RelE/ParE superfamily.

mBio·2025

Same author

Diverse genetic contexts of HicA toxin domains propose a role in anti-phage defense.

mBio·2024

Same author

Identifying the Binding Proteins of Small Ligands with the Differential Radial Capillary Action of Ligand Assay (DRaCALA).

Journal of visualized experiments : JoVE·2021

Same author

PasT of Escherichia coli sustains antibiotic tolerance and aerobic respiration as a bacterial homolog of mitochondrial Coq10.

MicrobiologyOpen·2020

Same author

Fatty acid starvation activates RelA by depleting lysine precursor pyruvate.

Molecular microbiology·2019

Search research articles

Related Experiment Video

Updated: Jul 13, 2026

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Published on: June 11, 2015

Phage portal proteins counteract stringent-response-mediated restriction.

Kristina Kronborg¹, Luokai Wang^1,2, Muriel Leandra Schicketanz^1,3

¹Department of Biology, University of Copenhagen, Copenhagen, Denmark.

Nature Communications

|July 11, 2026

Summary

Bacteriophage T7 uses its portal protein Gp8 to suppress the bacterial stringent response, a host defense mechanism. This interaction allows phages to overcome host-imposed barriers and replicate effectively.

More Related Videos

Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics

Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics

Published on: January 5, 2024

Following Cell-fate in E. coli After Infection by Phage Lambda

Following Cell-fate in E. coli After Infection by Phage Lambda

Published on: October 14, 2011

Related Experiment Videos

Last Updated: Jul 13, 2026

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Published on: June 11, 2015

Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics

Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics

Published on: January 5, 2024

Following Cell-fate in E. coli After Infection by Phage Lambda

Following Cell-fate in E. coli After Infection by Phage Lambda

Published on: October 14, 2011

Area of Science:

Microbiology
Virology
Molecular Biology

Background:

Bacteria employ physiological states, including the stringent response, to limit viral replication.
The stringent response, mediated by alarmone nucleotides (ppGpp and pppGpp), creates a growth-restrictive environment hindering phage infection.

Purpose of the Study:

To investigate how bacteriophages overcome host-imposed barriers, specifically the stringent response.
To elucidate the mechanism by which bacteriophage T7 counteracts the stringent response.

Main Methods:

Investigated the interaction between bacteriophage T7's portal protein Gp8 and host stringent response regulators RelA and SpoT.
Utilized portal mutations to assess the impact on alarmone accumulation, phage replication, and lysis.
Examined portal proteins from other coliphages for similar stringent-response-linked features.

Main Results:

Bacteriophage T7's portal protein Gp8 directly engages RelA and SpoT, inhibiting their synthetase activity and suppressing alarmone accumulation.
Mutations in Gp8 that disrupt this interaction lead to sustained alarmone elevation, delayed lysis, and impaired phage replication.
The negative impact of portal mutations is alleviated in alarmone-deficient host strains.
Similar stringent-response-linked features were observed in portal proteins of other coliphages.

Conclusions:

Bacterial stringent response acts as a significant barrier to phage infection.
Bacteriophage portal proteins possess a dual role, acting as essential virion components and antagonists of host stress physiology.
This mechanism of counteracting host stringent response is conserved among coliphages, highlighting a common viral strategy.