Related Experiment Video

Updated: Aug 14, 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

Regulation of filamentous bacteriophage length by modification of electrostatic interactions between coat protein and

J Greenwood1, G J Hunter, R N Perham

  • 1Department of Biochemistry, University of Cambridge, England.

Journal of Molecular Biology
|January 20, 1991
PubMed

Insights

Mutating bacteriophage fd gene VIII altered coat protein charge, preventing DNA packaging. This suggests electrostatic interactions regulate bacteriophage length and DNA packaging.

Area of Science:

  • Molecular Biology
  • Virology
  • Biophysics

Background:

  • Bacteriophage fd gene VIII encodes the major capsid protein.
  • The C-terminal region of the coat protein contains charged residues crucial for function.

Purpose of the Study:

  • To investigate the role of electrostatic interactions in bacteriophage fd DNA packaging and length regulation.
  • To analyze the effects of specific mutations in the coat protein's C-terminal region.

Main Methods:

  • Site-directed mutagenesis was used to create S47K and K48Q coat protein mutants.
  • Hybrid bacteriophage particles were constructed using mutant and wild-type coat proteins.
  • Particle length and DNA packaging capabilities were assessed.

Main Results:

  • The S47K mutation, increasing positive charge, prevented DNA encapsidation and incorporation into wild-type particles.
  • Hybrid virions of S47K and K48Q (reduced positive charge) were successfully constructed.
  • S47K/K48Q hybrids exhibited lengths intermediate to K48Q (longer) and wild-type bacteriophages.

Conclusions:

  • Filamentous bacteriophage length and DNA packaging are regulated by flexible electrostatic interactions between the coat protein C-terminus and DNA.
  • Wild-type bacteriophage fd efficiently packages DNA using a minimal number of coat protein subunits for compact DNA storage.

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

An Assay for Quantifying Protein-RNA Binding in Bacteria07:02

An Assay for Quantifying Protein-RNA Binding in Bacteria

Published on: June 12, 2019

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...
Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...