Related Experiment Videos
The small viral membrane-associated protein P32 is involved in bacteriophage PRD1 DNA entry
A Marika Grahn1, Rimantas Daugelavicius, Dennis H Bamford
1Department of Biosciences and Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
Abstract:
The lipid-containing bacteriophage PRD1 infects a variety of gram-negative cells by injecting its linear double-stranded DNA genome into the host cell cytoplasm, while the protein capsid is left outside. The virus membrane and several structural proteins are involved in phage DNA entry. In this work we identified a new infectivity protein of PRD1. Disruption of gene XXXII resulted in a mutant phenotype defective in phage reproduction. The absence of the protein P32 did not compromise the particle assembly but led to a defect in phage DNA injection. In P32-deficient particles the phage membrane is unable to undergo a structural transformation from a spherical to a tubular form. Since P32(-) particles are able to increase the permeability of the host cell envelope to a degree comparable to that found with wild-type particles, we suggest that the tail-tube formation is needed to eject the DNA from the phage particle rather than to reach the host cell interior.
Insights
Researchers identified a new bacteriophage PRD1 protein, P32, essential for DNA injection. P32 enables the phage membrane to form a tube for DNA ejection, crucial for infection of gram-negative cells.
Area of Science:
- Virology
- Molecular Biology
- Bacteriophage Research
Background:
- Bacteriophage PRD1 is a lipid-containing virus that infects gram-negative bacteria.
- PRD1 injects its double-stranded DNA genome into the host cytoplasm, leaving the capsid outside.
- Phage membrane and structural proteins are critical for DNA entry.
Purpose of the Study:
- To identify novel proteins involved in bacteriophage PRD1 infectivity.
- To elucidate the role of newly identified proteins in the phage infection process.
Main Methods:
- Genetic analysis of bacteriophage PRD1.
- Construction and characterization of mutant strains, specifically disruption of gene XXXII.
- Phenotypic analysis of mutant phage particles, focusing on assembly and DNA injection.
Main Results:
- Disruption of gene XXXII led to a mutant PRD1 with defective reproduction.
- The absence of protein P32 did not affect phage particle assembly.
- P32 deficiency resulted in a defect in phage DNA injection, with the membrane failing to form a tube.
- P32-deficient particles could still increase host cell envelope permeability similarly to wild-type particles.
Conclusions:
- Protein P32 is a novel and essential infectivity factor for bacteriophage PRD1.
- P32 is required for the structural transformation of the phage membrane into a tubular form.
- Tail-tube formation mediated by P32 is necessary for DNA ejection from the phage particle, not for host cell entry.