Related Experiment Video

Updated: Aug 20, 2026

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'
08:31

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'

Published on: May 26, 2013

The J gene of bacteriophage phi X174: in vitro analysis of J protein function

R K Hamatake, A Aoyama, M Hayashi

    Journal of Virology
    |May 1, 1985
    PubMed

    Insights

    The phi X174 phage J protein is essential for packaging viral DNA into infectious phage particles. This protein is not required for viral DNA synthesis but plays a crucial role in phage morphogenesis.

    Area of Science:

    • Virology
    • Molecular Biology
    • Structural Biology

    Background:

    • The J protein of bacteriophage phi X174 is a small, basic protein integral to the phage capsid structure.
    • Understanding the J protein's function is key to elucidating the mechanisms of viral DNA synthesis and phage assembly.

    Purpose of the Study:

    • To investigate the specific roles of the J protein in single-stranded viral DNA replication and bacteriophage phi X174 morphogenesis.
    • To determine if the J protein is essential for viral DNA synthesis or phage particle formation.

    Main Methods:

    • An in vitro system utilizing purified viral and host components was employed to study phi X174 DNA synthesis and morphogenesis.
    • Characterization of reaction products in the presence and absence of J protein was performed.

    Main Results:

    • The J protein was found to be dispensable for viral DNA synthesis.
    • The J protein is critically required for the efficient packaging of viral DNA into infectious phage particles.

    Conclusions:

    • The J protein's role is specifically in the morphogenesis of infectious phage, not in DNA replication.
    • The ability of J protein to bind both single-stranded and double-stranded DNA supports a model where it facilitates DNA packaging into the phage prohead.

    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

    Phage-Mediated Genetic Manipulation of the Lyme Disease Spirochete Borrelia burgdorferi09:01

    Phage-Mediated Genetic Manipulation of the Lyme Disease Spirochete Borrelia burgdorferi

    Published on: September 28, 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...
    Bacteriophages of the Human Virome01:23

    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...