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Purification and protein composition of PM2, the first lipid-containing bacterial virus to be isolated
H M Kivelä1, R H Männistö, N Kalkkinen
1Institute of Biotechnology, Institute of Biotechnology, Helsinki, Finland.
Abstract:
The marine, icosahedral bacteriophage PM2 was isolated in the late 1960s. It was the first phage for which lipids were firmly demonstrated to be part of the virion structure and it has been classified as the type organism of the Corticoviridae family. The host, Pseudoalteromonas espejiana BAL-31, belongs to a common group of marine bacteria. We developed a purification method producing virions with specific infectivity approximately as high as that of the lipid-containing phages PRD1 and φ6. The sensitivity of the virus to normally used purification media such as those containing sucrose is demonstrated. We also present an alternative host, a pseudoalteromonad, that allows enhanced purification of the virus under reduced salt conditions. We show, using N-terminal amino acid sequencing and comparison with the genomic sequence, that there are at least eight structural proteins in the infectious virus.
Insights
Marine bacteriophage PM2, the first phage with demonstrated lipids, has a new purification method. This method uses an alternative host for enhanced purification of the Corticoviridae family virus.
Area of Science:
- Virology
- Microbiology
- Structural Biology
Background:
- Marine bacteriophage PM2, classified under Corticoviridae, was the first phage with demonstrated lipids in its virion structure.
- The specific host for PM2 is Pseudoalteromonas espejiana BAL-31, a common marine bacterium.
- Early research on PM2 laid groundwork for understanding lipid-containing bacteriophages.
Purpose of the Study:
- To develop an improved purification method for marine bacteriophage PM2.
- To characterize the structural proteins of the infectious bacteriophage PM2 virion.
- To identify alternative hosts and conditions for enhanced viral purification.
Main Methods:
- Isolation and purification of bacteriophage PM2 from marine environments.
- Development of a novel purification protocol, assessing sensitivity to sucrose media.
- Utilizing an alternative pseudoalteromonad host for purification under reduced salt conditions.
- N-terminal amino acid sequencing of viral proteins and comparison with genomic data.
Main Results:
- A new purification method yields PM2 virions with high specific infectivity, comparable to phages PRD1 and φ6.
- The study demonstrates the sensitivity of PM2 to standard purification media like sucrose.
- An alternative host facilitates enhanced PM2 purification under reduced salt concentrations.
- At least eight structural proteins were identified in the infectious PM2 virion through sequencing and genomic comparison.
Conclusions:
- The developed purification method enhances the yield and infectivity of marine bacteriophage PM2.
- Understanding PM2's sensitivity to purification media is crucial for its study.
- The identification of at least eight structural proteins provides insights into the virion's composition and assembly.
- This research contributes to the characterization of the Corticoviridae family and lipid-containing phages.