Related Experiment Video
Updated: Jul 15, 2026
06:10
Following Cell-fate in E. coli After Infection by Phage Lambda
Published on: October 14, 2011
Phage integration and chromosome structure. A personal history
1Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA. AMC@stanford.edu
Annual Review of Genetics
|May 4, 2007
Summary
A 1962 model proposed lambda phage DNA integrates into bacterial chromosomes via circularization and recombination. This integration model, involving specific DNA sites, contrasted with prior theories of lateral attachment.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The integration of bacteriophage lambda into bacterial genomes is a fundamental process in molecular biology.
- Previous models suggested lateral attachment rather than direct chromosomal insertion.
Purpose of the Study:
- To present a model for lambda prophage integration into the bacterial chromosome.
- To summarize the experimental evidence leading to the proposed model.
Main Methods:
- Genetic characterization of specialized transducing phages (lambda-gal).
- Recombinational rescue of conditionally lethal mutations.
- Analysis of DNA circularization and reciprocal recombination.
Main Results:
- Proposed a two-step integration model: DNA circularization followed by site-specific recombination.
- Demonstrated that integration results in a cyclic permutation of gene order.
- Discovered conditionally lethal mutations serendipitously.
Conclusions:
- The proposed model provided a novel mechanism for bacteriophage integration.
- This work advanced the understanding of genetic recombination and phage-host interactions.
Related Concept Videos
01:26DNA 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...
00:43Lysogenic 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...
01:16Viral 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...
01:30Lytic Cycle of Bacteriophages
Bacteriophages, also known as phages, are specialized viruses that infect bacteria. A key characteristic of phages is their distinctive “head-tail” morphology. A phage begins the infection process (i.e., lytic cycle) by attaching to the outside of a bacterial cell. Attachment is accomplished via proteins in the phage tail that bind to specific receptor proteins on the outer surface of the bacterium. The tail injects the phage’s DNA genome into the bacterial cytoplasm. In the lytic replication...
01:23Bacteriophages 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...
01:20Viral Replication: Lytic Cycle
Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized lytic replication cycle in Escherichia coli (E. coli). This process ensures the rapid proliferation of the virus while ultimately leading to the destruction of the bacterial host.Attachment and DNA InjectionThe infection process begins with the recognition and binding of the T4 phage to the E. coli cell surface. Tail fibers of the phage...