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Bacteriophage PM2 has a protein capsid surrounding a spherical proteinaceous lipid core
Hanna M Kivelä1, Nisse Kalkkinen, Dennis H Bamford
1Department of Biosciences, University of Helsinki, Finland.
Abstract:
The marine double-stranded DNA (dsDNA) bacteriophage PM2, studied since 1968, is the type organism of the family Corticoviridae, infecting two gram-negative Pseudoalteromonas species. The virion contains a membrane underneath an icosahedral protein capsid composed of two structural proteins. The purified major capsid protein, P2, appears as a trimer, and the receptor binding protein, P1, appears as a monomer. The C-terminal part of P1 is distal and is responsible for receptor binding activity. The rest of the structural proteins are associated with the internal phospholipid membrane enclosing the viral genome. This internal particle is designated the lipid core. The overall structural organization of phage PM2 resembles that of dsDNA bacteriophage PRD1, the type organism of the family TECTIVIRIDAE:
Insights
Marine bacteriophage PM2, a double-stranded DNA virus, infects Pseudoalteromonas bacteria. Its structure, featuring a protein capsid and internal lipid core, resembles other viruses like PRD1.
Area of Science:
- Virology
- Microbiology
- Structural Biology
Background:
- Marine bacteriophage PM2 is the type organism of the Corticoviridae family.
- It infects gram-negative Pseudoalteromonas species.
- The virion consists of an icosahedral protein capsid and an internal membrane.
Purpose of the Study:
- To describe the structural organization of bacteriophage PM2.
- To identify key viral proteins and their functions.
- To compare PM2's structure with related viruses.
Main Methods:
- Purification and analysis of major capsid protein (P2) and receptor binding protein (P1).
- Structural characterization of the virion components.
- Comparative structural analysis with bacteriophage PRD1.
Main Results:
- Bacteriophage PM2 has an icosahedral protein capsid (P2 trimers) and an internal lipid core.
- Receptor binding protein (P1) is a monomer with a distal C-terminal domain for receptor interaction.
- The overall structure is similar to double-stranded DNA bacteriophage PRD1.
Conclusions:
- Bacteriophage PM2 exhibits a unique structural organization with a lipid core enclosed by a protein capsid.
- The identified proteins P1 and P2 play crucial roles in viral structure and host interaction.
- Structural similarities suggest a common evolutionary origin or convergent evolution with TECTIVIRIDAE family viruses.