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Head structure of bacteriophages T2 and T4
W Baschong1, U Aebi, C Baschong-Prescianotto
1M. E. Müller-Institute for High Resolution Electron Microscopy at the Biocenter, University of Basel, Switzerland.
Summary
Bacteriophage T2 and T4 capsid structures were analyzed using electron microscopy and gel electrophoresis. Both phages share a common capsid architecture with 960 copies of the major capsid protein, gp23*.
Area of Science:
- Virology
- Structural Biology
- Biophysics
Background:
- Bacteriophages are viruses that infect bacteria and have complex icosahedral capsid structures.
- Previous studies suggested discrepancies in the capsid architecture between bacteriophage T2 and T4.
- Understanding phage capsid structure is crucial for viral assembly and infection mechanisms.
Purpose of the Study:
- To precisely determine the capsid architecture of bacteriophages T2 and T4.
- To compare the length-to-width ratios and stereometric angles of T2 and T4 capsids.
- To quantify the copy numbers of the major capsid protein (gp23*) in T2 and T4.
Main Methods:
- Electron microscopy was used to analyze the dimensions and angles of bacteriophage T2 and T4 heads.
- Quantitative gel electrophoresis was employed to compare the copy numbers of the major capsid protein (gp23*).
- Various sample preparation methods were utilized for electron microscopy to ensure robust data.
Main Results:
- The length-to-width ratios and stereometric angles were evaluated for T2 and T4 bacteriophage heads.
- Copy numbers of the major capsid protein (gp23*) were compared between T2 and T4 phages.
- The data strongly support triangulation numbers T = 13 and Q = 21 for both T2 and T4.
Conclusions:
- Bacteriophages T2 and T4 share a common capsid architecture, consistent with a Q number of 21.
- This finding resolves previous discrepancies regarding the structural differences between T2 and T4.
- The capsid of both phages is composed of approximately 960 copies of the major capsid protein, gp23*.