Related Experiment Video

Updated: Aug 4, 2026

Visualizing Single-molecule DNA Replication with Fluorescence Microscopy
15:57

Visualizing Single-molecule DNA Replication with Fluorescence Microscopy

Published on: October 9, 2009

Bacteriophage P4 DNA replication

G Ziegelin1, E Lanka

  • 1Max-Planck-Institut für Molekulare Genetik, Abteilung Schuster, Berlin, Germany.

FEMS Microbiology Reviews
|August 1, 1995
PubMed

Insights

Satellite phage P4 replication in Escherichia coli relies on specific phage elements and host proteins. The alpha protein is key, possessing DNA binding, helicase, and primase activities for replication initiation.

Area of Science:

  • Molecular Biology
  • Virology
  • Bacteriology

Background:

  • Satellite phage P4 requires phage-encoded elements (ori, crr, gp alpha) for replication.
  • P4 replication is origin-specific, yielding monomeric form I DNA.
  • Host DNA polymerase III holoenzyme, SSB, DNA gyrase, and topoisomerase I are essential, but host initiation/priming functions are not.

Purpose of the Study:

  • To elucidate the multifunctional roles of the P4 alpha protein (gp alpha) in phage replication.
  • To characterize the specific activities and domains of gp alpha involved in P4 DNA synthesis.
  • To propose a model for P4 replication initiation.

Main Methods:

  • Analysis of P4 replication requirements, including phage-encoded elements and host factors.
  • Characterization of the activities of the P4 alpha protein (gp alpha).
  • Identification of sequence motifs and domains within gp alpha responsible for its functions.

Main Results:

  • The P4 alpha protein (gp alpha) exhibits three key activities: specific binding to ori and crr, 3'-->5' helicase activity, and RNA primer synthesis (primase activity).
  • These activities are localized to distinct domains within the gp alpha polypeptide.
  • Primase activity resides in the N-terminal half, while ori/crr binding is in the C-terminal portion.

Conclusions:

  • The P4 alpha protein (gp alpha) is a multifunctional initiator protein essential for P4 replication.
  • Its distinct functional domains facilitate specific DNA binding, unwinding, and primer synthesis.
  • The P4 replication mechanism shares similarities with that of simian virus 40.

More Related Videos

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins08:14

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins

Published on: February 25, 2017

T4 Bacteriophage and E. coli Interaction in the Murine Intestine: A Prototypical Model for Studying Host-Bacteriophage Dynamics In Vivo08:46

T4 Bacteriophage and E. coli Interaction in the Murine Intestine: A Prototypical Model for Studying Host-Bacteriophage Dynamics In Vivo

Published on: January 26, 2024

Related Concept Videos

Replication in Prokaryotes02:35

Replication in Prokaryotes

Overview
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...
Replication in Prokaryotes01:32

Replication in Prokaryotes

DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the single origin of replication (ori) on the cell's circular chromosome. Replication then proceeds around the entire circle of the chromosome in each direction from the two replication forks, resulting in two DNA molecules.
Many Proteins Work Together to Replicate the Chromosome
Replication is coordinated and carried out by a host of specialized...
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...
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...