Related Experiment Video

Updated: Aug 16, 2026

Following Cell-fate in E. coli After Infection by Phage Lambda
06:10

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

Published on: October 14, 2011

Filamentous phage assembly: morphogenetically defective mutants that do not kill the host

G P Smith1

  • 1Division of Biological Sciences, University of Missouri, Columbia 65211.

Virology
|November 1, 1988
PubMed

Insights

Filamentous phage assembly can be studied without host death using a modified phage (fd-tet). This system reveals essential genes for phage assembly and clarifies the role of a cis-acting sequence in phage production.

Area of Science:

  • Molecular Biology
  • Virology
  • Bacteriophage Genetics

Background:

  • Filamentous phage assembly occurs via extrusion without host lysis.
  • Blocked assembly leads to host death due to accumulated phage DNA and proteins.
  • Phage fd-tet, with a tetracycline-resistance gene, exhibits reduced host toxicity.

Purpose of the Study:

  • To investigate filamentous phage assembly mechanisms.
  • To identify genes essential for virion formation and maturation.
  • To analyze the function of the cis-acting sequence 'mos' in phage yield.

Main Methods:

  • Utilized phage fd-tet for propagation in tetracycline-containing media, minimizing host morbidity.
  • Employed transfection to initiate cultures, enabling sensitive assays of low-level phage production.
  • Studied morphogenetically defective mutants to determine gene requirements for assembly.

Main Results:

  • Genes III, VI, I, and IV are not essential for the initial DNA-protein complex formation.
  • Genes I and/or IV are critically required for the subsequent assembly process.
  • The cis-acting sequence 'mos' demonstrated variable effects on phage yield depending on experimental conditions.

Conclusions:

  • Established a system to study phage assembly independent of host cell death.
  • Elucidated the roles of specific genes in the filamentous phage life cycle.
  • Provided new insights into the regulation of phage production and assembly efficiency.

More Related Videos

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins09:40

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Published on: June 11, 2015

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility12:29

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility

Published on: March 11, 2022

Related Concept Videos

Lytic Cycle of Bacteriophages01:30

Lytic 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...
Lysogenic Cycle of Bacteriophages00:43

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...
Viral Replication: Lytic Cycle01:20

Viral 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...
Viral Replication: Lysogenic Cycle01:16

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...
DNA Bacteriophages01:26

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...
Inhibitors of Virion Maturation and Assembly01:19

Inhibitors of Virion Maturation and Assembly

As part of their replication cycle, certain viruses synthesize long precursor proteins called polyproteins within infected host cells. In human immunodeficiency virus (HIV), two major polyproteins are produced: Gag and Gag-Pol. The Gag polyprotein supplies the structural components of the virus, while Gag-Pol includes essential viral enzymes such as reverse transcriptase, integrase, and protease. After synthesis, these polyproteins move to the host cell membrane, where they assemble into an...